Heavy metal online monitoring system based on LIBS and dynamic aerosol enrichment

Abstract

The invention relates to the technical field of air monitoring, and discloses an LIBS (laser-induced breakdown spectroscopy) and dynamic aerosol enrichment-based heavy metal online monitoring system, which comprises a cyclone separator, an electrostatic deposition channel, a filter membrane belt, a flushing gas head and a connecting pipe, an air outlet of the cyclone separator is communicated with a fan; an air outlet of the fan is communicated with the electrostatic deposition channel, and a positive electrode plate and a negative electrode plate are arranged in the electrostatic deposition channel at intervals; the filter membrane covers the positive electrode plate, the filter membrane belt is connected end to end and is driven by a motor to rotate, and the filter membrane belt can move relative to the positive electrode plate; the flushing air head is located in an area defined by the filter membrane belt, and the flushing air head is arranged close to the filter membrane belt; the connecting pipe is located outside an area defined by the filter membrane belt, one end of the connecting pipe is close to an air outlet of the flushing air head, and the other end of the connecting pipe is connected with an air inlet of a detector. The problem of low detection accuracy in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the field of air monitoring technology, and more particularly to an online heavy metal monitoring system based on LIBS and dynamic aerosol enrichment. Background Art

[0002] Existing technologies for detecting heavy metals in the atmosphere typically use inductively coupled plasma mass spectrometry (ICP-MS), which uses high-temperature plasma to ionize metal elements in a sample, combined with mass spectrometry to separate and detect ions of different mass-to-charge ratios, to achieve accurate quantification of trace heavy metals (such as lead, cadmium, and arsenic). However, this method requires sample pretreatment (such as acid digestion), making the operation complex. Alternatively, it uses X-ray fluorescence spectrometry (XRF), which uses X-rays to excite heavy metal atoms in the sample to produce characteristic fluorescence, and then determines the element type and content through energy spectrum analysis.

[0003] Since the content of heavy metal aerosol particles in the atmosphere is very low, it is difficult to detect heavy metal aerosol particles by directly measuring the atmosphere using existing technologies, and the detection accuracy is very low. Summary of the Invention

[0004] This application provides an online heavy metal monitoring system based on LIBS and dynamic aerosol enrichment, aiming to solve the problem of low detection accuracy in existing technologies.

[0005] In one solution, a heavy metal online monitoring system based on LIBS and dynamic aerosol enrichment is provided, comprising: A cyclone separator, wherein the air outlet of the cyclone separator is connected to a fan; An electrostatic deposition channel, wherein the air outlet of the fan is connected to the electrostatic deposition channel, and a positive electrode plate and a negative electrode plate are arranged in the electrostatic deposition channel at intervals; A filter membrane belt, wherein the filter membrane is covered on the positive electrode plate, the filter membrane belt is connected end to end and rotated by a motor, and the filter membrane belt can move relative to the positive electrode plate; A flushing gas head, the flushing gas head is located in the area enclosed by the filter membrane belt, and the flushing gas head is arranged close to the filter membrane belt; A connecting tube is located outside the area enclosed by the filter membrane belt, one end of the connecting tube is close to the air outlet of the flushing gas head, and the other end is connected to the air inlet of the detector.

[0006] The lower end of the cyclone separator is provided with a collecting box for collecting large particles of impurities (impurities above PM10.0; The positive electrode plate and the negative electrode plate are fixedly connected to the inner wall of the electrostatic deposition channel; the flushing gas head is connected to the argon gas cylinder, nitrogen gas cylinder, or helium gas cylinder through a tube; by ablating heavy metal aerosols in a multi-gas environment, the heavy metals can reflect light of different wavelengths, thereby improving the accuracy of detection according to the detection of different light bands; Both ends of the filter membrane belt are connected with rotating shafts, and the motor is transmission-connected to the rotating shafts. When the motor does not rotate, the filter membrane belt is pressed on the positive electrode plate.

[0007] One side edge of the air inlet of the detector is in contact with the filter membrane belt, which can easily scrape the heavy metal aerosol on the filter membrane belt into the connecting tube, ensuring that almost all heavy metal aerosols enter the connecting tube.

[0008] The detector is a Laser Induced Breakdown Spectroscopy (LIBS), which uses high-energy laser to excite the sample surface to generate plasma and obtains the elemental composition and concentration information of the sample by analyzing the spectrum emitted by the plasma.

[0009] In one embodiment, the detector includes: a capture optical path for capturing heavy metal aerosol particles and a detection optical path for detecting the components of the heavy metal aerosol particles, and both the capture optical path and the detection optical path are electrically connected to a processor of the detector.

[0010] Specifically, the processor is fixedly connected in the detector.

[0011] In one embodiment, the capture light path includes: a first laser emitter, a first beam splitter, a first reflector, a second reflector, a first conical lens, a first focus lens group, a second focus lens group, a second conical lens, a second beam splitter, and a third reflector; the first laser emitter is fixedly connected to the top of the housing of the detector; the first beam splitter and the first reflector are in the same vertical direction; the first beam splitter and the second reflector are on the same horizontal plane; the second reflector and the second beam splitter are in the same vertical direction; the first reflector, the first conical lens, the first focus lens group, the second focus lens group, the second conical lens, the second beam splitter, and the third reflector are all located on the same horizontal plane; the first focus lens group and the second focus lens group are spaced apart to form a light capture area, and the detection laser of the detection light path passes through the light capture area; the light capture area is located in the connecting tube.

[0012] Specifically, the first laser emitter is electrically connected to the processor.

[0013] The first beam splitter, the first reflector, the second reflector, the third reflector, the first cone lens, the first beam reduction lens group, the second beam splitter, the second cone lens, and the second beam reduction lens group are all fixedly connected to the inside of the housing, and the components are spaced apart from each other.

[0014] The laser beam emitted by the first laser emitter is divided into a first laser and a second laser after passing through the first beam splitter; the first laser passes through the first reflector and enters the first axicon and the first beam reduction lens group in sequence to be refracted and irradiated into the light capture area, while the second laser passes through the second reflector and enters the second beam splitter and is reflected and irradiated onto the third reflector. The second laser reflected by the third reflector passes through the second beam splitter and then refracted through the second axicon and the second beam reduction lens group in sequence to irradiate into the light capture area. The first laser and the second laser overlap in the light capture area (with the same polarization direction) and are in opposite directions.

[0015] The laser beam emitted by the first laser emitter is a 780nm continuous laser with a diameter of 3mm. The first and second beam splitters are both polarization beam splitters, which can split the laser into two laser beams with equal intensity and perpendicular polarization directions. Before entering the beam splitter, the laser beam passes through a half-wave plate. The second laser beam is reflected by the second beam splitter and then enters a quarter-wave plate. It passes through the quarter-wave plate and reaches the third reflector, which reflects the second laser beam to the second beam splitter. After passing through the second beam splitter, the second laser beam is refracted by the second axicon and the second beam reduction lens group and illuminates the light capture area.

[0016] After the second laser beam exits the second beam splitter and passes through the quarter-wave plate, its polarization direction is opposite to that of the second laser beam exiting the second beam splitter. Therefore, after passing through the quarter-wave plate and being reflected by the third reflector, the second laser beam can pass through the second beam splitter without being reflected. Ultimately, the polarization directions of the first laser beam and the second laser beam are the same and on the same horizontal plane.

[0017] In one embodiment, the detection optical path includes: a second laser emitter, a receiver, a fourth reflector, and a third beam splitter; the second laser emitter is fixedly connected to the bottom of the housing, and the receiver is fixedly connected to the top of the second laser emitter; the fourth reflector and the third beam splitter are located in the same vertical direction, and the third beam splitter is located directly below the light capture area; the receiver is electrically connected to the processor.

[0018] Specifically, the second laser emitter is electrically connected to the processor.

[0019] The detection laser emitted by the second laser emitter passes through the fourth reflector and then through the third beam splitter into the light capture area. The metal aerosol in the light capture area is ablated by the detection laser and emits corresponding light. The light is irradiated on the third beam splitter and reflected by the third beam splitter to the receiver. The receiver transmits the signal to the processor for output. The processor outputs the corresponding signal to the terminal device, and the terminal device displays the type information of the heavy metal, etc.

[0020] In one embodiment, a pressure sensor is provided on the filter membrane belt. The pressure sensor is located on the positive electrode plate and within the area enclosed by the filter membrane belt. The filter membrane belt is pressed against the pressure sensor.

[0021] Specifically, by running the fan at rated power for a unit time, and then based on the known atmospheric pressure, the volume of the gas can be obtained. According to the difference in pressure sensor signals before and after the fan is turned (the total weight of all heavy metal elements), according to the formula , , It is the mass of the filter membrane belt after the fan runs for one unit time; is the mass of the filter membrane belt before the fan runs for one unit time; V is the volume of the gas; C is the concentration of heavy metals.

[0022] After the fan runs for a unit time, the filter membrane belt rotates at a uniform speed again, and the flushing gas head is connected to argon, nitrogen or helium to blow the heavy metals on the filter membrane belt into the connecting pipe (the flushing gas head discharges gas at a uniform speed). When the heavy metal aerosol in the connecting pipe enters the wide area, it is captured by the first laser and the second laser, restricting the movement of the heavy metal aerosol particles. The detection laser is irradiated in the light capture area, and the heavy metal aerosol particles in the light capture area are ablated and emit light. Different heavy metals emit light of different wavelengths, which is reflected by the third spectrometer to the receiver. The receiver transmits the signal to the processor for output, and the processor outputs the corresponding signal to the terminal device. The terminal device displays information such as the type and quantity of the heavy metal.

[0023] By controlling the first laser emitter to intermittently emit a laser beam, a light-trapping zone is intermittently formed to capture heavy metal aerosol particles within the connecting tube at different times. By detecting the laser irradiation within the light-trapping zone, the heavy metal aerosol particles within the light-trapping zone undergo ablation and emit corresponding light. This allows the type and amount of heavy metals within the connecting tube to be determined at different times (acquiring multiple sets of samples), enabling comprehensive sampling of the heavy metal aerosol particles within the connecting tube and improving the accuracy of the analysis and calculation of heavy metal types and contents.

[0024] Specifically, the first laser emitter and the second laser emitter work and stop at the same time, which can save energy consumption of the detector.

[0025] By statistically analyzing multiple groups of samples, the types and corresponding quantities of heavy metals can be obtained. For example, for iron, its mass can be calculated according to the formula: ,in is the number of particles in the iron sample, is the total number of all element particles in the sample; is the total weight of all heavy metal elements. Then substitute into the formula: , you can get the iron content.

[0026] In one embodiment, the first focusing lens group and the second focusing lens group have the same structure and size, the first focusing lens group includes a focusing lens and a convex lens, and the focusing lens is spaced apart from the convex lens; the convex lens of the first focusing lens group and the convex lens of the first focusing lens group are spaced apart, and the light capturing area is between the two convex lenses.

[0027] In one embodiment, the processor processes the light signal received by the processor through a convolutional neural network model and a residual network and attention mechanism.

[0028] In one embodiment, a transparent tube body connected to the connecting tube is provided in the detector, and the tube body runs through the detector; the light capture area is located in the tube body.

[0029] Specifically, the tube body is a colorless and transparent square glass tube.

[0030] In one embodiment, an air flow sensor is provided in the electrostatic deposition channel, and the air flow sensor is electrically connected to the processor.

[0031] Specifically, the fan is electrically connected to the processor.

[0032] In one embodiment, the air outlet of the tube body is connected to a collector.

[0033] Specifically, it is used to collect heavy metal aerosol particles and recover gases such as argon.

[0034] Beneficial effects of this application: By setting the cyclone separator, the large particle impurities in the air are separated, which can reduce the interference of large particle impurities on the detection result. The air treated by the cyclone separator passes through the electrostatic deposition channel. The positive electrode plate and the negative electrode plate in the electrostatic deposition channel form an electric field, so that the heavy metal aerosol particles move to the positive electrode plate. Therefore, the heavy metal aerosol particles are attached to the filter membrane belt on the positive electrode plate. With the movement of the filter membrane belt, the flushing gas head sprays gas to spray the heavy metal aerosol particles attached to the filter membrane belt into the connecting pipe. The connecting pipe is connected with the air inlet of the detector. The heavy metal aerosol particles enter the detector for detection.

[0035] By collecting the heavy metal aerosol particles in the air and then passing into the detector, the enrichment detection of the heavy metal aerosol particles in the air is realized, and the detection accuracy is improved. Moreover, by allowing the fan to run continuously, dynamic monitoring of the heavy metal in the air is realized. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0037] Figure 1 is a detection system structure schematic diagram in an embodiment of the present application; Figure 2 is a partial enlarged schematic diagram of A in Figure 1 Figure 3 is a capture light path and detection light path schematic diagram in an embodiment of the present application; Figure 4 is a detection system control flow schematic diagram in an embodiment of the present application; Reference signs in the drawings: ​1. Cyclone separator; 11. Collection box; 2. Fan; 3. Electrostatic deposition channel; 31. Positive electrode plate; 32. Negative electrode plate; 33. Filter membrane belt; 34. Air flow sensor; 4. Flushing head; 5. Connecting pipe; 6. Detector; 61. Capture light path; 611. First laser emitter; 612. First beam splitter; 613. First reflector; 614. Second reflector; 615. First conical lens; 616. First beam reduction lens group; 6161. Beam reduction lens; 6162. Convex lens; 617 , second beam reduction lens group; 618, second conical lens; 619, second spectrometer; 6110, third reflector; 6111, light capture area; 6112, half-wave plate; 6113, quarter-wave plate; 62, detection optical path; 621, second laser emitter; 622, receiver; 623, fourth reflector; 624, third spectrometer; 63, processor; 64, housing; 65, tube; 7, pressure sensor; 8, collector; 81, box; 82, filter membrane; 83, base; 9, terminal device. DETAILED DESCRIPTION

[0038] The specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application and not all embodiments. All other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0041] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0042] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0043] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0044] This application makes improvements and innovations and proposes the following embodiments.

[0045] In some embodiments, see Figures 1 to 4 , provides an online heavy metal monitoring system based on LIBS and dynamic aerosol enrichment, including: A cyclone separator 1, wherein the air outlet of the cyclone separator 1 is connected to a fan 2; The electrostatic deposition channel 3 is connected to the air outlet of the fan 2. A positive electrode plate 31 and a negative electrode plate 32 are arranged in the electrostatic deposition channel 3. The filter membrane belt 33 covers the positive electrode plate 31. The filter membrane belt 33 is connected end to end and is driven by a motor to rotate. The filter membrane belt 33 can move relative to the positive electrode plate 31. The flushing gas head 4 is located in the area enclosed by the filter membrane belt 33 and is close to the filter membrane belt 33; The connecting tube 5 is located outside the area enclosed by the filter membrane belt 33 , and one end of the connecting tube 5 is close to the air outlet of the flushing gas head 4 , and the other end is connected to the air inlet of the detector 6 .

[0046] The lower end of the cyclone separator 1 is provided with a collecting box 11 for collecting large particles of impurities (impurities above PM10.0); The positive electrode plate 31 and the negative electrode plate 32 are both fixedly connected to the inner wall of the electrostatic deposition channel 3; the flushing gas head 4 is connected to the argon gas cylinder, nitrogen gas cylinder, or helium gas cylinder through the tube 65; by ablating the heavy metal aerosol in a multi-gas environment, the heavy metal can reflect light of different wavelengths, thereby improving the detection accuracy according to the detection of different light bands; Both ends of the filter membrane belt 33 are connected to a rotating shaft, and the motor is transmission-connected to the rotating shaft. When the motor does not rotate, the filter membrane belt 33 is pressed onto the positive electrode plate 31 .

[0047] One side edge of the air inlet of the detector 6 is in contact with the filter membrane belt 33, which can easily scrape the heavy metal aerosol on the filter membrane belt 33 into the connecting tube 5, ensuring that almost all heavy metal aerosol enters the connecting tube 5.

[0048] The detector 6 is a laser induced breakdown spectrometer (LIBS), which is a spectrometer that uses high-energy laser to excite the sample surface to generate plasma and obtains the elemental composition and concentration information of the sample by analyzing the spectrum emitted by the plasma.

[0049] By setting up a cyclone separator 1 to separate large particle impurities in the air, the interference of large particle impurities on the detection results can be reduced. The air treated by the cyclone separator 1 then passes through the electrostatic deposition channel 3. The positive electrode plate 31 and the negative electrode plate 32 in the electrostatic deposition channel 3 form an electric field, so that the heavy metal aerosol particles move toward the positive electrode plate 31. Therefore, the heavy metal aerosol particles adhere to the filter membrane belt 33 located on the positive electrode plate 31. As the filter membrane belt 33 moves, the flushing gas head 4 will spray gas to spray the heavy metal aerosol particles attached to the filter membrane belt 33 into the connecting pipe 5. The connecting pipe 5 is connected to the air inlet of the detector 6, and the heavy metal aerosol particles enter the detector 6 for detection.

[0050] By collecting the heavy metal aerosol particles in the air and then passing them into the detector 6, the enrichment detection of the heavy metal aerosol particles in the air is achieved, thereby improving the detection accuracy. In addition, by allowing the fan 2 to run continuously, dynamic monitoring of heavy metals in the air is achieved.

[0051] In one embodiment, the detector 6 includes a capture optical path 61 for capturing heavy metal aerosol particles and a detection optical path 62 for detecting the composition of the heavy metal aerosol particles. Both the capture optical path 61 and the detection optical path 62 are electrically connected to a processor 63 of the detector 6. The capture optical path 61 is used to capture and position the heavy metal aerosol particles, allowing the detection optical path 62 to illuminate the heavy metal aerosol particles and perform detection and analysis of the heavy metal aerosol particles.

[0052] Specifically, the processor 63 is fixedly connected in the detector 6 .

[0053] In one embodiment, the capture optical path 61 includes: a first laser emitter 611, a first beam splitter 612, a first reflector 613, a second reflector 614, a first aconic lens 615, a first beam reduction lens group 616, a second beam reduction lens group 617, a second aconic lens 618, a second beam splitter 619, and a third reflector 6110; the first laser emitter 611 is fixedly connected to the top of the housing 64 of the detector 6; the first beam splitter 612 and the first reflector 613 are in the same vertical direction; the first beam splitter 612 and the second reflector 61 4 are on the same horizontal plane; the second reflector 614 and the second beam splitter 619 are in the same vertical direction; the first reflector 613, the first conical lens 615, the first beam-reducing lens group 616, the second beam-reducing lens group 617, the second conical lens 618, the second beam splitter 619, and the third reflector 6110 are all located on the same horizontal plane; the first beam-reducing lens group 616 and the second beam-reducing lens group 617 are spaced apart to form a light-trapping region 6111, through which the detection laser light of the detection optical path 62 passes; the light-trapping region 6111 is located within the connecting tube 5. This arrangement can split the laser beam emitted by the first laser emitter 611 into two beams, a first laser beam and a second laser beam, with the same polarization direction but opposite propagation directions. The first laser beam and the second laser beam converge through the first beam-reducing lens group 616 and the second beam-reducing lens group 617 to form the light-trapping region 6111, thereby facilitating the capture of heavy metal aerosol particles.

[0054] Specifically, the first laser emitter 611 is electrically connected to the processor 63 .

[0055] The first beam splitter 612, the first reflector 613, the second reflector 614, the third reflector 6110, the first conical lens 615, the first focus reduction lens group 616, the second beam splitter 619, the second conical lens 618, and the second focus reduction lens group 617 are all fixedly connected to the inside of the outer shell 64, and the components are arranged at intervals from each other.

[0056] The laser beam emitted by the first laser emitter 611 is divided into a first laser and a second laser after passing through the first beam splitter 612; the first laser passes through the first reflector 613 and enters the first conical lens 615 and the first beam reduction lens group 616 in sequence, is refracted and irradiates the light capture area 6111, while the second laser passes through the second reflector 614 and enters the second beam splitter 619 and is reflected and irradiates the third reflector 6110. The second laser reflected by the third reflector 6110 passes through the second beam splitter 619 and then passes through the second conical lens 618 and the second beam reduction lens group 617 in sequence, is refracted and irradiates the light capture area 6111. The first laser and the second laser coincide in the light capture area 6111 (with the same polarization direction) and are in opposite directions.

[0057] The laser beam emitted by the first laser emitter 611 is a 780nm continuous laser with a diameter of 3mm. The first beam splitter 612 and the second beam splitter 619 are both polarization beam splitters, which can split the laser into two laser beams with equal intensity and perpendicular polarization directions. Before entering the beam splitter, the laser beam passes through a half-wave plate 6112. The second laser beam is reflected by the second beam splitter 619 and then enters a quarter-wave plate 6113. After passing through the quarter-wave plate 6113, it reaches the third reflector 6110, which reflects the second laser beam back to the second beam splitter 619. After passing through the second beam splitter 619, the second laser beam is refracted by the second conical lens 618 and the second beam reduction lens group 617, and then illuminates the light capture area 6111.

[0058] After the second laser beam exits the second beam splitter 619 and passes through the quarter-wave plate 6113, its polarization direction is opposite to that of the second laser beam exiting the second beam splitter 619. Therefore, after passing through the quarter-wave plate 6113 and reflecting off the third reflector 6110, the second laser beam can pass through the second beam splitter 619 without being reflected. Ultimately, the polarization directions of the first laser beam and the second laser beam are the same and on the same horizontal plane.

[0059] In one embodiment, the detection optical path 62 includes: a second laser emitter 621, a receiver 622, a fourth reflector 623, and a third beam splitter 624. The second laser emitter 621 is fixedly connected to the bottom of the housing 64, and the receiver 622 is fixedly connected to the top of the second laser emitter 621. The fourth reflector 623 and the third beam splitter 624 are located in the same vertical direction, and the third beam splitter 624 is located directly below the light capture area 6111. The receiver 622 is electrically connected to the processor 63. This simple configuration allows for a more compact arrangement of the second laser emitter 621 and the receiver 622, reducing the size of the detector 6.

[0060] Specifically, the second laser emitter 621 is electrically connected to the processor 63 .

[0061] The detection laser emitted by the second laser emitter 621 passes through the fourth reflective member 623, enters the light trapping area 6111 through the third light splitting member 624, and the metal aerosol in the light trapping area 6111 is ablated by the detection laser to emit corresponding light. The light is irradiated on the third light splitting member 624 and reflected to the receiver 622 through the third light splitting member 624. The receiver 622 transmits a signal to the processor 63 for output. The processor 63 outputs a corresponding signal to the terminal device 9, and the terminal device 9 displays the type information of the heavy metal.

[0062] In one embodiment, the filter membrane belt 33 is provided with a pressure sensor 7, the pressure sensor 7 is located on the positive electrode plate 31, and the pressure sensor 7 is located in the area enclosed by the filter membrane belt 33, and the filter membrane belt 33 is pressed on the pressure sensor 7. The pressure sensor 7 can be set to facilitate obtaining the pressure change of the filter membrane belt 33 to determine the weight of the heavy metal aerosol particles.

[0063] Specifically, by operating the fan 2 at rated power for a unit time, and according to the known atmospheric pressure, the volume of the gas can be obtained. According to the pressure sensor 7 signal difference (total weight of all heavy metal elements) before the fan 2 rotates and after the fan 2 operates for a unit time, according to the formula , , is the mass of the filter membrane belt 33 after the fan 2 operates for a unit time; is the mass of the filter membrane belt 33 before the fan 2 operates for a unit time; V is the volume of the gas; and C is the concentration of the heavy metal.

[0064] After the fan 2 operates for a unit time, the filter membrane belt 33 rotates at a uniform speed, and the flushing gas head 4 is connected to argon, nitrogen or helium, and the heavy metal on the filter membrane belt 33 is blown into the connecting pipe 5 (the flushing gas head 4 uniformly discharges gas). When the heavy metal aerosol in the connecting pipe 5 enters the wide area, it is captured by the first laser and the second laser, limiting the movement of the heavy metal aerosol particles. The detection laser irradiates in the light trapping area 6111, and the heavy metal aerosol particles in the light trapping area 6111 emit light after ablation. Different heavy metals emit light of different wavebands, which is reflected to the receiver 622 through the third light splitting member 624. The receiver 622 transmits a signal to the processor 63 for output. The processor 63 outputs a corresponding signal to the terminal device 9, and the terminal device 9 displays the type and quantity information of the heavy metal.

[0065] By controlling the first laser emitter 611 to intermittently emit a laser beam, an intermittent light capture region 6111 is formed to capture heavy metal aerosol particles within the connecting tube 5 at different times. By detecting the laser irradiation within the light capture region 6111, the heavy metal aerosol particles within the light capture region 6111 undergo ablation and emit corresponding light. This allows the type and amount of heavy metals within the connecting tube 5 to be determined at different times (acquiring multiple sets of samples), achieving sufficient sampling of the heavy metal aerosol particles within the connecting tube 5 and improving the accuracy of the analysis and calculation of the heavy metal types and contents.

[0066] Specifically, the first laser emitter 611 and the second laser emitter 621 work and stop at the same time, which can save energy consumption of the detector 6.

[0067] By statistically analyzing multiple groups of samples, the types and corresponding quantities of heavy metals can be obtained. For example, for iron, its mass can be calculated according to the formula: ,in is the number of particles in the iron sample, is the total number of all element particles in the sample; is the total weight of all heavy metal elements. Then substitute into the formula: , you can get the iron content.

[0068] In one embodiment, the first and second focusing lens groups 616 and 617 have the same structure and size. The first focusing lens group 616 includes a focusing lens 6161 and a convex lens 6162. The focusing lens 6161 and the convex lens 6162 are spaced apart. The convex lens 6162 of the first focusing lens group 616 is spaced apart from the convex lens 6162 of the second focusing lens group 616, and a light capture region 6111 is formed between the two convex lenses 6162. The combination of focusing lens 6161 and convex lens 6162 improves the laser beam reduction and increases the light intensity, thereby better capturing heavy metal aerosol particles.

[0069] In one embodiment, the processor 63 processes the light signals received by the processor 63 through a convolutional neural network model, a residual network, and an attention mechanism. The convolutional neural network model, the residual network, and the attention mechanism work together to process the multiple sets of photos obtained by the receiver 622, thereby improving the data processing capability and thus improving the accuracy of detection.

[0070] Receiver 622 includes a detector and an isCMOS camera. The ablated emission light is split by a grating and then illuminated by the detector. The detector converts the optical signal into a corresponding electrical signal, which is then transmitted to processor 63 for processing to obtain the corresponding spectral signal. The isCMOS camera features an ultrafast optical gate width (less than 3ns cathode optical gate width) and a built-in gate width controller with an accuracy of less than 10ps. By precisely controlling the isCMOS gate time, acquisition can be selected at the specific moment when the plasma emission spectrum signal is strongest and interference is minimized. The isCMOS has a 2048×2048 pixel array, which enables high spectral resolution during LIBS spectral acquisition. In LIBS analysis, the characteristic spectral lines of different elements are often very close, and high spectral resolution can clearly distinguish these spectral lines. The isCMOS camera has both imaging and spectral modes, capable of producing high-quality photographs and spectral images.

[0071] The processor 63 processes and calculates different spectral signals and / or images through a convolutional neural network model, a residual network, and an attention mechanism, and outputs corresponding heavy metal type and content information.

[0072] Specifically, in the convolutional neural network model, residual network and attention mechanism, the core structure of the model is designed. First, residual-convolution feature extraction layer; Each residual unit consists of two 1D convolutional layers (kernel size = 3), batch normalization (BatchNorm), and ReLU activation; gradient disappearance is alleviated by skip connections.

[0073] By formula: ; This formula is the core expression of the residual block in the residual network (ResNet), which combines convolution operations, activation functions and skip connections. The specific parameters are defined as follows: ‌ : Input tensor, shape (B, L, C), where: B: Batch Size; L: one-dimensional input sequence length (such as the number of spectral wavelength points); C: number of input channels (such as single-channel or multi-channel characteristics of spectral signals); ‌Conv1D(x)‌: One-dimensional convolution operation, parameters include: Convolution kernel: kernel size K (e.g. K=3K=3), number of output channels D; ‌Stride‌: controls the convolution sliding step (usually 1); ‌Padding‌: Keep the input and output lengths consistent (e.g. symmetrical padding).

[0074] The output shape is (B, L, D), and D=C (dimensionality matching is achieved by adjusting the number of channels); ReLU(x)‌: Rectified linear unit, which performs nonlinear mapping on the convolution result: ReLU(x)=max(0,x), retaining positive values ​​and suppressing negative values, enhancing the nonlinear expression ability of the model.

[0075] ‌: Convert the original input Added to the result of convolution activation, it forms a residual connection. This prevents the gradient from vanishing in deep networks and forces the model to learn residual mapping. . Make sure that the number of Conv1D output channels DD is the same as The number of channels C is equal to (the number of channels can be adjusted by 1×1 convolution).

[0076] formula Through the collaboration of convolutional feature extraction and residual learning mechanism, the model's ability to learn heavy metal features in spectral signals is improved.

[0077] Second, attention enhancement module; ‌Channel Attention (SE Block)‌: Perform global average pooling on the feature map to generate channel weights and enhance the key wavelength response according to the formula: ,in is the weight matrix of the first fully connected layer‌; is the weight matrix ‌ of the second fully connected layer, σ is the Sigmoid function; GAP(F) is the global average pooling operation, which compresses the input feature map F (usually with dimensions H×W×C) into a 1×1×C vector in the spatial dimension (H×W), retaining the channel (C) information.

[0078] After dimensionality reduction, it is activated by ReLU and then Dimensional recovery channel dimension‌, the design is achieved by lightweight parameters ( 、 ) and nonlinear activation (ReLU, Sigmoid) effectively balances computational efficiency and feature expression capabilities.

[0079] Spatial Attention (CBAM): By superimposing maximum pooling and average pooling, a spatial weight map is generated to suppress noise interference areas.

[0080] Third, lightweight classification head; Replacing the fully connected layer with global average pooling reduces the number of parameters; Mapped to the heavy metal category probability distribution through ‌Softmax output‌.

[0081] Fourth, data enhancement and training strategies; Spectral data preprocessing: Noise injection: Add Gaussian noise (SNR = 10-20dB) to simulate the on-site interference environment; ‌Random Band Masking‌: Randomly mask 5%-15% of the wavelength region to improve the model's robustness to local feature loss.

[0082] Training optimization; Loss function: cross entropy loss + L1 regularization (sparse weight matrix); Optimizer: AdamW (learning rate = 3e-4, weight decay = 1e-5); Two-stage training; Pre-training: Use laboratory calibration data (5,000 sets) to optimize basic feature extraction capabilities; establish a heavy metal characteristic spectral line database (covering 20 heavy metals including Hg, Pb, and Cd); Fine-tuning: Mix lab data with field perturbation data (7:3) to enhance generalization.

[0083] This model integrates laboratory calibration and field interference data to solve the problem of data distribution offset. Through residual-attention collaboration, ResNet ensures the stability of deep features, and the attention mechanism dynamically suppresses noise, improving the detection accuracy in complex environments. In this model, 16 heavy metal elements can be analyzed simultaneously, and the single detection time is less than 60s. It can still maintain an accuracy of >90% in an environment with SO2>100ppm and humidity>90%, and has strong anti-interference ability.

[0084] In one embodiment, a transparent tube 65 is provided within the detector 6 and communicates with the connecting tube 5. The tube 65 extends through the detector 6, and the light capture area 6111 is located within the tube 65. The transparent tube 65 facilitates the passage of laser light, minimizing energy loss and preventing deflection.

[0085] Specifically, the tube body 65 is a colorless and transparent square glass tube.

[0086] In one embodiment, an air flow sensor 34 is provided in the electrostatic deposition channel 3 and is electrically connected to the processor 63. The provision of the air flow sensor 34 can better determine the volume of gas flowing through the electrostatic deposition channel 3, thereby facilitating better calculation of heavy metal concentrations.

[0087] Specifically, the fan 2 is electrically connected to the processor 63 .

[0088] In one embodiment, the air outlet of the tube body 65 is connected to a collector 8. The collector 8 can prevent the metal aerosol particles from entering the air again, while realizing the recovery of nitrogen, argon or helium.

[0089] Specifically, the collector 8 includes a box body 81, a filter membrane 82, and a base 83; the air outlet of the tube body 65 is inserted into the box body 81 and is located at the bottom position of the box body 81. The number of filter membranes 82 is multiple and spaced apart in sequence, and the air outlet of the tube body 65 passes through all the filter membranes 82.

[0090] An air outlet is provided at the top of the box body 81 , and the bottom of the box body 81 is open. The bottom opening of the box body 81 is sealed with the base 83 through threaded engagement; the filter membrane 82 can be taken out from the opening of the box body 81 or put into the box body 81 .

[0091] The above are merely optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application. Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may make changes, modifications, replacements, and variations to the above embodiments within the scope of the present invention.

Claims

1. The heavy metal online monitoring system based on LIBS and dynamic aerosol enrichment is characterized by: include: A cyclone separator, wherein the air outlet of the cyclone separator is connected to a fan; An electrostatic deposition channel, wherein the air outlet of the fan is connected to the electrostatic deposition channel, and a positive electrode plate and a negative electrode plate are arranged in the electrostatic deposition channel at intervals; A filter membrane belt, wherein the filter membrane is covered on the positive electrode plate, the filter membrane belt is connected end to end and rotated by a motor, and the filter membrane belt can move relative to the positive electrode plate; A flushing gas head, the flushing gas head is located in the area enclosed by the filter membrane belt, and the flushing gas head is arranged close to the filter membrane belt; A connecting tube is located outside the area enclosed by the filter membrane belt, one end of the connecting tube is close to the air outlet of the flushing gas head, and the other end is connected to the air inlet of the detector.

2. The heavy metal online monitoring system according to claim 1, characterized in that: The detector comprises: a capturing optical path for capturing heavy metal aerosol particles and a detecting optical path for detecting the components of the heavy metal aerosol particles. Both the capturing optical path and the detecting optical path are electrically connected to the processor of the detector.

3. The heavy metal online monitoring system according to claim 2, characterized in that: The capture optical path includes: a first laser emitter, a first beam splitter, a first reflector, a second reflector, a first conical lens, a first beam reduction lens group, a second beam reduction lens group, a second conical lens, a second beam splitter, and a third reflector; the first laser emitter is fixedly connected to the top of the housing of the detector; the first beam splitter and the first reflector are in the same vertical direction; the first beam splitter and the second reflector are on the same horizontal plane; the second reflector and the second beam splitter are in the same vertical direction; the first reflector, the first conical lens, the first beam reduction lens group, the second beam reduction lens group, the second conical lens, the second beam splitter, and the third reflector are all located on the same horizontal plane; the first beam reduction lens group and the second beam reduction lens group are spaced apart to form a light capture area, and the detection laser of the detection optical path passes through the light capture area; the light capture area is located in the connecting tube.

4. The heavy metal online monitoring system according to claim 3, characterized in that: The detection optical path includes: a second laser emitter, a receiver, a fourth reflector, and a third beam splitter; the second laser emitter is fixedly connected to the bottom of the housing, and the receiver is fixedly connected to the top of the second laser emitter; the fourth reflector and the third beam splitter are located in the same vertical direction, and the third beam splitter is located directly below the light capture area; the receiver is electrically connected to the processor.

5. The heavy metal online monitoring system according to claim 1, characterized in that: A pressure sensor is provided on the filter membrane belt. The pressure sensor is located on the positive electrode plate and is located in the area enclosed by the filter membrane belt. The filter membrane belt is pressed on the pressure sensor.

6. The heavy metal online monitoring system according to claim 4, characterized in that: The first focusing lens group and the second focusing lens group have the same structure and size. The first focusing lens group includes a focusing lens and a convex lens, and the focusing lens is spaced apart from the convex lens. The convex lens of the first focusing lens group and the convex lens of the first focusing lens group are spaced apart, and the light capturing area is between the two convex lenses.

7. The heavy metal online monitoring system according to claim 4, characterized in that: The processor processes the light signal received by the processor through a convolutional neural network model and a residual network and attention mechanism.

8. The heavy metal online monitoring system according to claim 4, characterized in that: A transparent tube body connected to the connecting tube is provided in the detector, and the tube body passes through the detector; the light capture area is located in the tube body.

9. The heavy metal online monitoring system according to claim 2, characterized in that: An air flow sensor is provided in the electrostatic deposition channel, and the air flow sensor is electrically connected to the processor.

10. The heavy metal online monitoring system according to claim 8, characterized in that: The air outlet of the tube body is connected with a collector.

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