A particulate matter detection system and method

Abstract

The application discloses a particulate matter detection system method, wherein the detection system comprises a sampling module for collecting gas in a region to be detected and inputting into a gas path channel; a laser module for generating detection laser passing through the gas path channel; a first concentration detection module for receiving, amplifying and converting a scattered light signal scattered by particulate matter in the gas path channel into an electric signal; and a processing module for converting the electric signal into particulate matter concentration information. The application adopts a light scattering principle to detect different concentrations of samples to be detected in sections through a combination of a photomultiplier tube, a photodiode and an algorithm, thereby improving a particulate matter monitoring range, expanding a measurement range, ensuring accuracy and improving the measurement range. The application has the advantages of simple structure, mass production, real-time monitoring of various particle sizes of particulate matter through an algorithm, solution to complex and various problems of equipment, satisfaction of different application requirements, wide measurement range, high measurement accuracy, fast detection rate and wide application, etc.

Description

Technical Field

[0001] This invention discloses a particulate matter detection system and method, belonging to the field of environmental monitoring technology. Background Technology

[0002] Particulate matter, consisting of solid or liquid particles in the atmosphere, is a major source of air pollution. Its composition is highly complex and variable. Particulate matter concentration monitoring is necessary in various sectors, including production and daily life. Examples include monitoring particulate matter emissions from factory flues to limit emissions and reduce anthropogenic pollution; monitoring atmospheric dust in the environment to monitor air quality; monitoring flammable and explosive dust in mines to ensure safe working environments; and particulate matter sensors in commercial and residential air purification equipment. Particulate matter concentration detection is crucial for emission standards and production safety standards. Common methods for particulate matter concentration detection include sedimentation, inductively coupled plasma (ICP) methods, and light scattering methods.

[0003] The light scattering method utilizes the Tyndall effect, a phenomenon where light deviates from its original propagation direction and scatters in all directions when passing through an inhomogeneous medium, to detect particulate matter concentration. It calculates the number of particles or the particle concentration by measuring changes in light intensity.

[0004] However, when using light scattering to detect particulate matter concentration, the composition of particulate matter is very complex because it includes solid or liquid particles of different sizes. Furthermore, the concentration of particulate matter changes constantly with environmental changes, making it difficult for existing detection equipment to measure the concentration information of such complex and variable particulate matter. Summary of the Invention

[0005] The purpose of this application is to provide a particulate matter detection system and method to solve the technical problem of the limited range of particulate matter concentration measurement in existing detection equipment. To achieve the above objective, this invention proposes a particulate matter detection system and method, the specific solution of which is as follows:

[0006] A particulate matter detection system includes: a sampling module, a laser module, a first concentration detection module, and a processing module;

[0007] The sampling module is used to collect gas from the area to be tested and to introduce the gas into the gas path channel;

[0008] The laser module is used to generate a detection laser, which passes through the gas path channel;

[0009] The first concentration detection module is used to receive and amplify the scattered light signal of the detection laser after passing through the particulate matter in the gas path channel, and convert the scattered light signal into an electrical signal;

[0010] The processing module is used to convert the electrical signal into particulate matter concentration information.

[0011] Preferably, the first concentration detection module includes a photomultiplier tube and a transmission device;

[0012] The photomultiplier tube is used to receive and amplify the scattered light signal, and convert the scattered light signal into an electrical signal.

[0013] The transmission device is disposed between the photomultiplier tube and the gas path channel, and is used to control the scattered light signal reaching the photomultiplier tube.

[0014] Preferably, it also includes a control module connected to the processing module;

[0015] The control module is connected to the light-transmitting device and is used to control the light-transmitting area of ​​the light-transmitting device according to the particulate matter concentration information obtained by the processing module.

[0016] Preferably, it also includes a second concentration detection module;

[0017] The second concentration detection module includes a photodiode;

[0018] The photodiode is used to receive the scattered light signal and convert the scattered light signal into an electrical signal.

[0019] Preferably, it also includes an optical recovery module;

[0020] The optical recovery module is located on the light output path of the detection laser and is used to absorb the laser light passing through the gas path channel.

[0021] Preferably, the sampling module includes an air pump and a temperature and humidity sensing unit;

[0022] The air pump is used to pump gas from the area to be tested into the air passage.

[0023] The temperature and humidity sensing unit is disposed in the gas passage and connected to the processing module. It is used to detect the temperature and humidity information of the gas in the gas passage and transmit the temperature and humidity information to the processing module.

[0024] Preferably, it also includes a display unit;

[0025] The display unit is connected to the processing module;

[0026] The display unit is used to receive and display the particulate matter concentration information and the temperature and humidity information.

[0027] A method for detecting particulate matter includes the following steps:

[0028] Step 1: Collect gas from the area to be tested and introduce the gas into the gas path channel;

[0029] Step 2: Inject a detection laser beam into the gas passage;

[0030] Step 3: Receive and amplify the scattered light signal from the detection laser as it passes through the gas path channel and the scattered light signal is converted into an electrical signal;

[0031] Step 4: Convert the electrical signal into particulate matter concentration information.

[0032] Preferably, before step two, the method further includes detecting the temperature and humidity information of the gas.

[0033] Preferably, after step four, the method further includes calibrating the particulate matter concentration information based on the temperature and humidity information, and outputting and displaying the particulate matter concentration information.

[0034] Beneficial Effects: This invention employs the principle of light scattering, combining high-sensitivity, low-noise photomultiplier tubes and photodiodes with algorithms to perform segmented detection of samples with different concentrations. This improves the particulate matter monitoring range, expands the measurement scope, and ensures accuracy while increasing the measurement range. The simple structure facilitates mass production. The algorithm enables real-time monitoring of particulate matter of various sizes, solving the problem of complex and diverse equipment, meeting different application needs, and offering advantages such as wide measurement range, high measurement accuracy, fast detection rate, and broad applicability. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a particulate matter detection system according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the optical path system of the detection module in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the optical path of the first concentration detection module in an embodiment of the present invention;

[0038] Figure 4 This is a structural diagram of a particulate matter detection system according to an embodiment of the present invention;

[0039] Figure 5 This is a graph showing the change of the concentration of the sample to be tested over time in the host computer software of this invention.

[0040] In the diagram: 001, Sampling module; 002, High concentration detection module; 003, Low concentration detection module; 004, Data acquisition module; 005, Calculation and analysis module; 006, Network transmission module; 101, Filter; 102, Fan; 103, Temperature and humidity sensing unit; 104, Sampling pipe; 201, Laser; 202, Aperture; 203, Beam expander; 204, First focusing lens; 205, Measured area; 206, Optical trash can; 301, Scattered light; 302, Second focusing lens; 303, Motorized aperture; 304, Third focusing lens; 305, First slit; 306, Photomultiplier tube; 307, Second slit; 308, Photodiode. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of the invention.

[0042] A particulate matter detection system includes: a sampling module, a laser module, a first concentration detection module, and a processing module;

[0043] The sampling module is used to collect gas from the area to be tested and introduce the gas into the gas path channel. The sampling module includes an air pump and a temperature and humidity sensing unit. The air pump is used to pump the gas from the area to be tested into the gas path channel. The temperature and humidity sensing unit is set in the gas path channel and connected to the processing module. It is used to detect the temperature and humidity information of the gas in the gas path channel and transmit the temperature and humidity information to the processing module.

[0044] like Figure 1 As shown, in one embodiment of the present invention, the sampling module is specifically a sampling module 001, such as... Figure 4 As shown, the gas path channel is a sampling pipe 104, and the air pump can be a blower or a micro fan; specifically, in this embodiment, it is a blower 102. The sampling module 001 includes a filter 101, a blower 102, a temperature and humidity sensing unit 103, and a sampling pipe 104. The filter 101 is installed at the air inlet of the sampling pipe 104 and is used to filter out substances other than the particulate matter to be tested, such as oil stains and water vapor. The blower 102 is used to draw gas from the area to be tested into the sampling pipe 104, which is made of a material resistant to high temperatures and acid / alkali corrosion. The temperature and humidity sensing unit 103 is used to detect the ambient temperature and humidity.

[0045] The laser module generates a detection laser, which passes through a gas path channel. The detection laser overlaps with or is perpendicular to the gas path channel. The invention also includes an optical recovery module, which is positioned along the exit path of the detection laser to absorb the laser beam passing through the gas path channel, thus eliminating the influence of the laser beam on the detection results. Specifically, the optical recovery module can be an optical trash can or a beam collector.

[0046] Specifically, such as Figure 2 As shown, in this embodiment, the laser module is specifically the main optical path system, and the optical recycling module is specifically selected as the optical trash can 206. The main optical path system includes a laser 201, an aperture 202, a beam expander 203, a focusing lens 204, a detection area 205, and the optical trash can 206. The laser 201 has sufficient stability to meet the needs of long-term detection, i.e., long-term online monitoring. The aperture of the aperture 202 is continuously adjustable within the range of 1–10 mm, and the magnification of the beam expander 203 is continuously adjustable within the range of 1.5–5x.

[0047] The first concentration detection module receives and amplifies the scattered light signal from particles scattered by the detection laser through the gas path channel, and converts the scattered light signal into an electrical signal. This first concentration detection module includes a photomultiplier tube and a transmission device. The photomultiplier tube receives and amplifies the scattered light signal and converts it into an electrical signal. The transmission device is located between the photomultiplier tube and the gas path channel and controls the scattered light signal reaching the photomultiplier tube. The transmission device also includes a device for collecting the scattered light, making the luminous flux of the scattered light reaching the photomultiplier tube more concentrated for detection. A second concentration detection module is also included; the second concentration detection module includes a photodiode; the photodiode receives the scattered light signal and converts it into an electrical signal.

[0048] Specifically, such as Figure 3 As shown, in this embodiment, the first concentration detection module is a low-concentration detection module, which can be used to detect particulate matter concentrations in the range of 0–2000 μg / m³. 3 The second concentration detection module is a high-concentration detection module, used to detect particulate matter concentrations greater than or equal to 2000 μg / m³. 3 Gases. For example... Figure 1As shown, in this embodiment, the high-concentration detection module 002 and the low-concentration detection module 003 are mainly used to receive light signals scattered by particulate matter or pollutants. The high-concentration detection module 002 and the low-concentration detection module 003 are located on both sides of the gas path channel, perpendicular to the main optical path system. The low-concentration module 003 includes a photomultiplier tube 306, and a second focusing lens 302, an electric aperture 303, a third focusing lens 304, and a first slit 305 sequentially arranged between the photomultiplier tube 306 and the detection area 205. The electric aperture 303 is connected to the control unit and is used to control the light-transmitting area of ​​the light-transmitting device according to the particulate matter concentration information obtained by the processing module. The above devices are also used to collect scattered light 301, so that the weak scattered light 301 is more concentrated and focused on the photomultiplier tube 306. The photomultiplier tube 306 has extremely high sensitivity, fast response, and low noise, and is suitable for detecting extremely weak light signals. The weak light signal is converted and amplified into an electrical signal. Figure 4 As shown, the high-concentration detection module 002 includes a second slit 307 and a photodiode 308. Scattered light 301 is emitted from the area to be tested 205, passes through the second slit 307, and is received by the photodiode 308, which converts the scattered light signal into an electrical signal.

[0049] The processing module converts electrical signals into particulate matter concentration information. The detection system also includes a control module connected to the processing module; the control module is connected to the transmitting device and controls the light-transmitting area of ​​the transmitting device based on the particulate matter concentration information obtained by the processing module. The invention also includes a display unit connected to the processing module; the display unit receives and displays particulate matter concentration information and temperature and humidity information.

[0050] Specifically, in this embodiment, the processing module includes a data acquisition module 004, a computer analysis module 005, and a network transmission module 006. The data acquisition module 004 is connected to the high-concentration detection module 002, the low-concentration detection module 003, and the temperature and humidity sensing unit 103, and is used to receive the electrical signals converted by the high-concentration detection module 002 and the low-concentration detection module 003, as well as the temperature and humidity information in the gas. It then sends the electrical signals and temperature and humidity information to the computer analysis module 005. The computer analysis module 005 uses the principle that particulate matter concentration is proportional to the intensity of scattered light to calculate particulate matter concentration information from the received electrical signals, and uses software algorithms to analyze the temperature and humidity information to calibrate the calculated particulate matter concentration information. Specifically, the peak value of the electrical pulses output by the photomultiplier tube and photodiode changes proportionally with the scattered light. After the photo-to-electric conversion is completed, the μA-level electrical signal is proportionally amplified by an operational amplifier, and the integration process is controlled by a microcontroller to analyze the particulate matter information. The data collected by the temperature and humidity sensing unit 103 is analyzed by software algorithms, and the results are calibrated to improve measurement accuracy. The difference between the integrated signal mean and the noise floor mean is multiplied by a conversion coefficient to obtain the particulate matter concentration. The test results are then smoothed using algorithms such as exponential smoothing curves. Subsequently, the computer analysis module 005 transmits the particulate matter concentration information to the network transmission module 006, which includes a human-computer interaction unit for displaying the obtained particulate matter concentration information.

[0051] A particulate matter detection method includes the following steps: Step 1, collecting gas from the area to be tested and introducing the gas into a gas path channel; Step 2, detecting the temperature and humidity information of the gas; Step 3, injecting a detection laser beam into the gas path channel; Step 4, receiving and amplifying the scattered light signal from the detection laser as it passes through the particulate matter in the gas path channel, and converting the scattered light signal into an electrical signal; Step 5, converting the electrical signal into particulate matter concentration information; Step 6, calibrating the particulate matter concentration information based on the temperature and humidity information, and outputting and displaying the particulate matter concentration information.

[0052] According to the detection system in this embodiment, the corresponding detection method is as follows: Figure 4 As shown, after the device is powered on, the fan 102 starts to work, generating negative pressure, drawing the gas from the area to be tested into the sampling pipe 104 with sufficient mechanical strength and reaching the detection area 205.

[0053] Laser 201 emits a 635nm continuous laser beam. After stray light interference is effectively filtered out by aperture 202, the beam is expanded and collimated by beam expander 203. The collimated beam is then focused by first focusing lens 204, with the focal point located at the center of detection area 205. The incident laser beam is perpendicular to the gas path at a 90° angle, ensuring that the beam is most concentrated and has the greatest intensity in detection area 205, resulting in more significant scattering. After passing through detection area 205, the main beam is absorbed by optical bin 206. The installation of optical bin 206 must meet certain requirements, placing it in a position that can completely absorb the main beam to ensure that it does not interfere with the detection results.

[0054] In one embodiment, when there are no particulate matter in the detection area 205, the laser beam emitted by the laser 201 is completely absorbed by the optical trash can 206 after passing through a series of components, without scattering. Figure 5 As shown, the concentration of the sample to be tested changes over time in the host computer software. In the host computer software, the particulate matter concentration is 0 from 0 to 16 seconds. When particulate matter is present in the detection area 205, the photomultiplier tube and photodiode simultaneously receive the scattered light 301, and the particulate matter concentration information is obtained through analysis by the calculation and analysis module 005. When particulate matter is present in the detection area 205 and the concentration is low (0–2000 μg / m³), the concentration decreases. 3 Scattered light 301 emanates from the test area 205 and enters the channel of the low-concentration detection module 003, where it first collects scattered light within the range of 20° to 160°. The scattered light 301 passes through the second focusing lens 302, the motorized aperture 303, the third focusing lens 304, and the slit 305, finally reaching the photomultiplier tube 306. Specifically, the photomultiplier tube 306 features extremely high sensitivity, fast response, and low noise, making it suitable for detecting extremely weak light signals. By fine-tuning the second focusing lens 302 and the third focusing lens 304, the scattered beam is made thinnest at the photomultiplier tube 306. The slit 305 is positioned close to the photomultiplier tube 306, and its size is adjusted to the minimum to ensure that only scattered light passes through, preventing stray light from entering and damaging the receiver. The network transmission module 006 outputs the particulate matter information acquired by the low-concentration detection module 003.

[0055] When the particulate matter concentration information is obtained through the calculation and analysis module 005, and the displayed gas concentration is high (>2000 μg / m³),... 3 The electric aperture 303 is closed to protect the low concentration detection module 003, and only the photodiode in the high concentration detection module 002 receives the scattered light. The network transmission module 006 outputs the particulate matter information acquired by the high concentration detection module 003.

[0056] This embodiment employs the principle of light scattering, combining a high-sensitivity, low-noise photomultiplier tube, a photodiode, and an algorithm to perform segmented detection of samples with different concentrations. This improves the particulate matter monitoring range and expands the measurement area, ensuring accuracy while increasing the measurement range. The structure is simple, facilitating mass production. The algorithm enables real-time monitoring of particulate matter of various sizes, solving the problem of complex and diverse equipment, meeting different application needs, and offering advantages such as wide measurement range, high measurement accuracy, fast detection rate, and wide applicability.

[0057] The above embodiments illustrate only one implementation of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A particulate matter detection system, characterized in that, include: Sampling module, laser module, first concentration detection module, and processing module; The sampling module is used to collect gas from the area to be tested and to introduce the gas into the gas path channel; The laser module is used to generate a detection laser, which passes through the gas path channel; The first concentration detection module is used to receive and amplify the scattered light signal of the detection laser after passing through the particulate matter in the gas path channel, and convert the scattered light signal into an electrical signal; The processing module is used to convert the electrical signal into particulate matter concentration information; It also includes a second concentration detection module; The second concentration detection module includes a photodiode; The photodiode is used to receive the scattered light signal and convert the scattered light signal into an electrical signal; The first concentration detection module is a low-concentration detection module, and the second concentration detection module is a high-concentration detection module. The high-concentration and low-concentration detection modules are located on opposite sides of the gas path channel, perpendicular to the main optical path system. The low-concentration module includes a photomultiplier tube, and a second focusing lens, an electric aperture, a third focusing lens, and a first slit sequentially disposed between the photomultiplier tube and the detection area. When the particulate matter concentration obtained by the processing module is >2000 μg / m³, the module is activated. 3 When the light is off, the electric aperture is closed to protect the low-concentration detection module, and only the high-concentration detection module receives the scattered light. The processing module outputs the particulate matter information acquired by the high-concentration detection module.

2. The particulate matter detection system according to claim 1, characterized in that, The first concentration detection module includes a photomultiplier tube and a transmission device; The photomultiplier tube is used to receive and amplify the scattered light signal, and convert the scattered light signal into an electrical signal. The transmission device is disposed between the photomultiplier tube and the gas passage, and is used to control the scattered light signal reaching the photomultiplier tube.

3. The particulate matter detection system according to claim 2, characterized in that, It also includes a control module connected to the processing module; The control module is connected to the transmission device and is used to control the light-transmitting area of ​​the transmission device according to the particulate matter concentration information obtained by the processing module.

4. The particulate matter detection system according to claim 1, characterized in that, It also includes an optical recycling module; The optical recovery module is located on the light output path of the detection laser and is used to absorb the laser light passing through the gas path channel.

5. The particulate matter detection system according to claim 1, characterized in that, The sampling module includes an air pump and a temperature and humidity sensing unit; The air pump is used to pump gas from the area to be tested into the air passage. The temperature and humidity sensing unit is disposed in the gas passage and connected to the processing module. It is used to detect the temperature and humidity information of the gas in the gas passage and transmit the temperature and humidity information to the processing module.

6. The particulate matter detection system according to claim 5, characterized in that, It also includes a display unit; The display unit is connected to the processing module; The display unit is used to receive and display the particulate matter concentration information and the temperature and humidity information.

7. A particulate matter detection method based on the particulate matter detection system according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Collect gas from the area to be tested and introduce the gas into the gas path channel; Step 2: Inject a detection laser beam into the gas passage; Step 3: Receive and amplify the scattered light signal from the detection laser as it passes through the gas path channel and the scattered light signal is converted into an electrical signal; Step 4: Convert the electrical signal into particulate matter concentration information.

8. The particulate matter detection method according to claim 7, characterized in that, Before step two, the method also includes detecting the temperature and humidity information of the gas.

9. The particulate matter detection method according to claim 8, characterized in that, Following step four, the method further includes calibrating the particulate matter concentration information based on the temperature and humidity information, and then outputting and displaying the particulate matter concentration information.

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