CN113504166B - Aerosol concentration detection method, device and system - Google Patents
Aerosol concentration detection method, device and system Download PDFInfo
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- 238000001514 detection method Methods 0.000 title claims abstract description 153
- 239000000443 aerosol Substances 0.000 title claims abstract description 107
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- 238000000034 method Methods 0.000 abstract description 12
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
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- G01N15/075—
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Abstract
The invention discloses a method, a device and a system for detecting aerosol concentration, wherein the detection method comprises the following steps: the extinction element is used for absorbing the incident light which directly passes through the detection chamber, and the diaphragm is used for preventing the incident light which is not absorbed by the extinction element from returning to the detection chamber; a plurality of photodiodes are utilized to respectively receive multi-angle scattered light formed by scattering of incident light in a detection chamber and convert the multi-angle scattered light into an electric signal; and analyzing and calculating the plurality of electric signals to obtain the concentration of the aerosol. The method can improve the accuracy of aerosol concentration detection.
Description
Technical Field
The present invention relates to the field of aerosol detection technologies, and in particular, to a method, an apparatus, and a system for detecting aerosol concentration.
Background
Aerosols refer to a gaseous dispersion system of solid or liquid particles suspended in a gaseous medium, so aerosols themselves are suspended particulate matter having different physical properties. The properties of the particles such as the median diameter and the particle density are different.
Most of the detection technologies such as the current mask filtering efficiency and the high-efficiency filter detection are that salt or oily aerosol with certain attribute is generated to pass through the mask or the filter, and then the concentration of aerosol at the upstream and downstream of the mask or the filter is detected by using an aerosol photometer, so that the filtering efficiency of the mask or the filter is calculated. However, due to the differences in the mastering of aerosol generation techniques, the differences in aerosol types, and the changes in the physical properties of the aerosol after passing through a mask or filter, the accuracy of the current light scattering aerosol photometer in measuring mass concentration is reduced due to these differences and changes.
According to Mie scattering theory, the scattering light intensity is related to the scattering angle and the wavelength of the light wave, so that when the wavelength of the light wave is fixed, the back-push can obtain that the scattering light intensity at different angles is related to the particle size of uniform particles; by using this relationship, the approximate particle size range of the particulate matter can be deduced on the premise of measuring the multi-angle scattering light intensity, thereby confirming the physical properties of the aerosol.
Three main forms of scattered light measurement systems that are common to the current aerosol mass concentration are a near forward scattered light measurement system, a vertical scattered light measurement system, and a back scattered light measurement system. The scattered light intensity, sensitivity and particle size are different. Meanwhile, the scattered light intensities of the aerosols at different angles are measured, and the aerosols with different properties can be distinguished and the mass concentration measurement can be completed by utilizing the difference of the scattered light intensities of the aerosols at different angles.
When the light scattering method is used for measuring the mass concentration of the aerosol, if the aerosol dispersion occurs in the light chamber and the lens light source is polluted, the accuracy of the aerosol measurement can be affected. It is therefore highly necessary to protect the sample gas to be measured from dispersion of the aerosol in the light chamber during measurement. The light source, when passing through the optical chamber, may similarly form stray light in the optical chamber that affects the measurement without processing the optical path. The source of astigmatism is mainly light source divergence and light path end irradiation module inner wall generated scattering.
The above information disclosed in this background section is only for enhancement of understanding of the background section of the application and therefore it may not form the prior art that is already known to those of ordinary skill in the art.
Disclosure of Invention
Aiming at the problems pointed out in the background technology, the invention provides an aerosol concentration detection method, an aerosol concentration detection device and an aerosol concentration detection system, which improve the accuracy of aerosol concentration detection.
In order to achieve the aim of the invention, the invention is realized by adopting the following technical scheme:
the invention provides an aerosol concentration detection method, which comprises the following steps:
absorbing incident light passing straight through the detection chamber with an extinction element, and preventing the incident light not absorbed by the extinction element from returning to the detection chamber with a diaphragm;
utilizing a plurality of photodiodes to respectively receive multi-angle scattered light formed by scattering of incident light in the detection chamber and convert the multi-angle scattered light into an electric signal;
and analyzing and calculating a plurality of the electric signals to obtain the concentration of the aerosol.
In some embodiments of the present application, a first photodiode is utilized to receive scattered light in a first direction formed by scattering incident light in the detection chamber, and convert the scattered light into a first electrical signal;
receiving scattered light in a second direction formed by scattering of incident light in the detection chamber by using a second photodiode, and converting the scattered light into a second electric signal;
and analyzing and calculating the first electric signal and the second electric signal to obtain the concentration of the aerosol.
In some embodiments of the present application, an included angle between the first direction and the direct propagation direction of the incident light in the detection chamber is 90 °, and an included angle between the second direction and the direct propagation direction of the incident light in the detection chamber is 45 °;
alternatively, the first direction and the direct propagation direction of the incident light in the detection chamber have an included angle of 120 degrees, and the second direction and the direct propagation direction of the incident light in the detection chamber have an included angle of 60 degrees.
In some embodiments of the present application, the first direction scattered light is formed into parallel light by using a first parallel hemispherical mirror, and the parallel light is converged into a light spot at the first photodiode by using a first condensing hemispherical mirror;
and utilizing a second parallel hemispherical mirror to scatter light in the second direction to form parallel light, and utilizing a second light converging hemispherical mirror to converge the parallel light into a light spot at the second photodiode.
In some embodiments of the present application, a first signal processor is utilized to receive the first electrical signal generated by the first photodiode and feed back the first electrical signal to a control center;
receiving the second electric signal generated by the first photodiode by using a second signal processor and feeding back the second electric signal to a control center;
the control center analyzes and calculates the first electric signal and the second electric signal.
In some embodiments of the present application, the cylindrical mirror is used to form the incident light emitted by the light source into a flat-shaped linear light before the incident light enters the detection chamber;
stray light in incident light is eliminated by a light source diaphragm.
In some embodiments of the present application, aerosol entering the air inlet of the detection chamber is divided into two paths, one path is used as a sample gas to directly enter the detection chamber, and the other path enters the sheath flow branch for generating a sheath flow to form a package on the sample gas entering the detection chamber.
In some embodiments of the present application, a filter and a flowmeter are disposed on the sheath flow branch, clean gas in the sheath flow branch is divided into two paths, one path is used for generating sheath gas flow to wrap the sample gas entering the detection chamber, and the other path is used for protecting the optical element.
The invention also provides a device for realizing the aerosol concentration detection method, which comprises the following steps:
a detection chamber through which an aerosol flows;
the light source chamber is used for irradiating incident light to the detection chamber, and a light source diaphragm is arranged in the light source chamber;
an optical trap chamber which is arranged opposite to the light source chamber, wherein incident light reaches the optical trap chamber through the detection chamber, and an extinction element is arranged in the optical trap chamber;
the light source chamber is arranged between the light source chamber and the light trap chamber, the included angles between the light source chamber and the light trap chamber are different, and each light receiving chamber is internally provided with a photodiode for receiving scattered light formed by scattering incident light in the detection chamber and converting the scattered light into an electric signal.
The invention also provides an aerosol concentration detection system, which comprises the aerosol concentration detection device, and further comprises:
a sheath gas branch communicated with the gas inlet of the detection chamber and used for generating clean sheath gas flow so as to form a package on aerosol flowing into the detection chamber;
and the negative feedback regulating branch is communicated with the air outlet of the detection chamber.
Compared with the prior art, the invention has the advantages and positive effects that:
in the aerosol concentration detection device disclosed by the application, the multi-angle scattered light of the incident light is detected through the light trap chamber and the plurality of scattered light receiving chambers at the same time, so that the basic physical property of the aerosol is confirmed, the mass concentration of the aerosol is measured, and the accuracy of aerosol concentration detection is improved.
The optical chambers are relatively independent and do not interfere with each other, the detection means is more direct, and the detection structure is more accurate.
Other features and advantages of the present invention will become apparent upon review of the detailed description of the invention in conjunction with the drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it will be obvious that the drawings in the following description are some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort to a person skilled in the art.
FIG. 1 is a schematic diagram of an aerosol concentration detection system according to an embodiment;
fig. 2 is a schematic structural view of an aerosol concentration detection apparatus according to an embodiment;
FIG. 3 is a cross-sectional view of an aerosol concentration detection apparatus according to an embodiment taken along the axis of a light source chamber and a light trap chamber;
fig. 4 is a cross-sectional view of a vertically scattered light receiving chamber according to an embodiment.
Reference numerals:
10-light source chambers, 11-light sources, 12-light source diaphragms, 13-cylindrical mirrors, 14-light source protection air inlet nozzles and 15-light source adjusting seats;
20-light trap chamber, 21-extinction element, 22-light trap diaphragm and 23-light trap protection air inlet nozzle;
30-first direction scattering light receiving chamber, 31-first parallel hemispherical mirror, 32-first condensing hemispherical mirror, 33-first photodiode, 34-first signal processor, 35-lens protection air inlet nozzle
40-second direction scattering light receiving chamber, 41-second signal processor;
50-detecting chamber, 51-air inlet, 52-air outlet, 53-sample air pipe, 54-air outlet nozzle and 55-air inlet nozzle;
60-sheath flow branch, 61-filter, 62-flowmeter;
70-negative feedback regulation branch, 71-aspiration pump, 72-aspiration flowmeter, 73-aspiration filter.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
In the description of the present application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.
The terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.
Example 1
The embodiment discloses an aerosol concentration detection method, which comprises the following steps:
absorbing incident light passing straight through the detection chamber by using an extinction element, and preventing the incident light not absorbed by the extinction element from returning to the detection chamber by using a diaphragm;
a plurality of photodiodes are utilized to respectively receive multi-angle scattered light formed by scattering of incident light in a detection chamber and convert the multi-angle scattered light into an electric signal;
and analyzing and calculating the plurality of electric signals to obtain the concentration of the aerosol.
The method can detect the multi-angle scattered light of the incident light in the detection chamber at the same time, so as to confirm the basic physical property of the aerosol and measure the mass concentration, and improve the accuracy of aerosol concentration detection.
The optical chambers are relatively independent and do not interfere with each other, the detection means is more direct, and the detection structure is more accurate.
In some embodiments of the present application, a first photodiode is utilized to receive scattered light in a first direction formed by scattering of incident light in a detection chamber, and convert the scattered light into a first electrical signal;
receiving scattered light in a second direction formed by scattering of incident light in the detection chamber by using a second photodiode, and converting the scattered light into a second electric signal;
and analyzing and calculating the first electric signal and the second electric signal to obtain the concentration of the aerosol.
The scattered light in two directions is detected, and the device structure is not excessively complicated on the premise of ensuring the detection accuracy.
As a specific embodiment, the included angle between the first direction and the direct propagation direction of the incident light in the detection chamber is 90 degrees, so as to detect the vertically scattered light; the included angle between the second direction and the direct propagation direction of the incident light in the detection chamber is 45 degrees, so that the near forward scattered light is detected.
In another embodiment, the angle between the first direction and the direct propagation direction of the incident light in the detection chamber is 120 degrees, so as to detect the back scattered light; the included angle between the second direction and the direct propagation direction of the incident light in the detection chamber is 60 degrees, so that the near forward scattered light is detected.
In some embodiments of the present application, a first parallel hemispherical mirror is used to scatter incident light into first direction scattered light in a detection chamber to form parallel light, and a first condensing hemispherical mirror is used to collect the parallel light into a light spot at a first photodiode, where the first photodiode converts an optical signal into a first electrical signal.
The first signal processor is used for receiving the first electric signal generated by the first photodiode and feeding back the first electric signal to the control center.
And utilizing a second parallel hemispherical mirror to scatter the incident light in a second direction formed by scattering in the detection chamber to form parallel light, utilizing a second condensing hemispherical mirror to condense the parallel light into a light spot at a second photodiode, and converting the light signal into a second electric signal by the second photodiode.
The second signal processor is used for receiving the second electric signal generated by the first photodiode and feeding back the second electric signal to the control center.
The control center analyzes and calculates the first electric signal and the second electric signal to obtain the basic physical properties and the mass concentration of the aerosol.
The detection method can effectively process and detect the incident light by utilizing a simple optical principle through the optical element, and has high detection precision and low cost.
In some embodiments of the present application, the cylindrical mirror is used to form flat in-line light before the incident light emitted by the light source enters the detection chamber, so as to perform the functions of condensing light and reducing the detection area, and thus, the aerosol concentration detection precision is improved.
Stray light in incident light is eliminated by utilizing a light source diaphragm, and the influence of the stray light on aerosol detection is avoided.
In some embodiments of the present application, aerosol in the air inlet that gets into the detection room is divided into two ways, and one way is as the direct detection room that gets into of sample gas, and another way gets into sheath flow branch road for produce sheath air current in order to form the parcel to the sample gas that gets into the detection room, avoid aerosol to take place to disperse in the detection room, further improve detection effect and precision.
The sheath flow branch is provided with a filter and a flowmeter, the filter filters particles in the gas path to form clean gas, the clean gas in the sheath flow branch is divided into two paths, one path is used for generating sheath gas flow to wrap sample gas entering the detection chamber, and the other path is used for protecting the optical element.
Example two
The embodiment discloses an aerosol concentration detection device which detects aerosol concentration by using the method disclosed in the embodiment.
Referring to fig. 2 to 4, the aerosol concentration detection apparatus includes a detection chamber 50, a light source chamber 10, a light trap chamber 20, and a plurality of scattered light receiving chambers provided at the outer periphery of the detection chamber 50, and associated optical elements provided in the respective light chambers.
The detection chamber 50 provides a detection space for detecting the concentration of the sample gas, and the detection chamber 50 is provided with an air inlet 51 and an air outlet 52, and aerosol flows into the detection chamber 50 through the air inlet 51 and flows out through the air outlet 52.
A plurality of optical windows are arranged around the detection chamber 50, and the optical windows are in one-to-one correspondence with the optical chambers.
The optical window between the light source chamber 10 and the detection chamber 50 facilitates the entry of incident light from the light source into the detection chamber.
The optical window between the light trapping chamber 20 and the detection chamber 50 facilitates the light source to reach the light trapping chamber 20 directly through the detection chamber 50.
The optical windows between the different scattered light receiving chambers and the detection chamber 50 facilitate the entry of scattered light of different directions formed by the scattering of the incident light within the detection chamber 50 into the corresponding scattered light receiving chamber.
Referring to fig. 3, an incident light path emitted from the light source chamber 10 directly irradiates into the detection chamber 50, and a light source diaphragm 12 is arranged in the light source chamber 10 to eliminate light source stray light and avoid the influence of the stray light on aerosol detection.
The number of the light source diaphragms 12 may be plural, and in this embodiment, two light source diaphragms 12 are provided, which are respectively labeled as a first light source diaphragm and a second light source diaphragm, so as to improve stray light eliminating effect.
The light trapping chamber 20 is disposed opposite to the light source chamber 10, symmetrically disposed on both sides of the detection chamber 50, and incident light emitted from the light source chamber 10 passes through the detection chamber 50 and reaches the light trapping chamber 20.
An extinction element 21, such as coated extinction glass, is disposed within the optical trap chamber 20 for absorbing incident light entering the optical trap chamber 20.
Each scattered light receiving chamber is arranged between the light source chamber 10 and the light trap chamber 20, the included angle between each scattered light receiving chamber and the light trap chamber 20 is different, and a photodiode is arranged in each scattered light receiving chamber and is used for receiving scattered light formed by scattering incident light in the detection chamber 50 and converting the scattered light into an electric signal.
The multi-angle scattered light of the incident light is detected simultaneously through the light trap chamber 20 and the plurality of scattered light receiving chambers, so that the basic physical property of the aerosol is confirmed, the mass concentration of the aerosol is measured, and the accuracy of aerosol concentration detection is improved.
The optical chambers are relatively independent and do not interfere with each other, the detection means is more direct, and the detection structure is more accurate.
In some embodiments of the present application, a parallel hemispherical mirror and a light-condensing hemispherical mirror are sequentially disposed in a light scattering receiving chamber along a propagation path of scattered light, and the scattered light sequentially irradiates the light to be converged into a light spot through the parallel hemispherical mirror and the light-condensing hemispherical mirror and is received by a photodiode.
One end of the scattered light receiving chamber is provided with a signal processor for receiving and processing the electric signal generated by the photodiode.
As a specific embodiment, the scattered light receiving chamber has two, which correspond to the first direction scattered light receiving chamber 30 and the second direction scattered light receiving chamber 40, respectively.
In the first way, as shown in fig. 2, an angle between the scattered light in the first direction scattered light receiving chamber 30 and the direct propagation direction of the incident light in the detecting chamber 50 is 90 ° to detect the vertically scattered light.
The angle between the scattered light in the second direction scattered light receiving chamber 40 and the straight traveling direction of the incident light in the detection chamber 50 is 45 deg. to detect near forward scattered light.
In the second mode, the angle between the scattered light in the first direction scattered light receiving chamber 30 and the direct propagation direction of the incident light in the detecting chamber 50 is 120 ° to detect the backscattered light.
The angle between the scattered light in the second direction scattered light receiving chamber 40 and the straight traveling direction of the incident light in the detection chamber 50 is 60 deg. to detect near-forward scattered light.
In some embodiments of the present application, referring to fig. 2 and 3, a light source 11 is disposed in the light source chamber 10 for providing incident light. The light source 11 is a single wavelength light source, providing single wavelength incident light. The incident light may be a laser.
A cylindrical mirror 13 is provided in the light source chamber 10 along the propagation path of the incident light, and the cylindrical mirror 13 is located upstream of the light source diaphragm 12 in accordance with the propagation path of the incident light.
The cylindrical mirror 13 is used for forming the incident light emitted by the light source 11 into flat linear light before entering the detection chamber 50, and has the functions of condensing light and reducing the detection area, thereby being beneficial to improving the aerosol concentration detection precision.
In some embodiments of the present application, referring to fig. 3, an optical trap diaphragm 22 is further disposed in the optical trap chamber 20, and after the incident light passes through the detection chamber 50, the incident light enters the optical trap chamber 20, a part of the incident light is absorbed by the extinction element 21, and another small part of the incident light is reflected, and the reflected light is consumed by multiple reflections in the optical trap chamber 20, where the optical trap diaphragm 22 is used for preventing the reflected light from returning into the detection chamber 50 to affect aerosol detection.
In some embodiments of the present application, the internal structures of the first direction-scattering light receiving chamber 30 and the second direction-scattering light receiving chamber 40 are the same, and fig. 4 is a cross-sectional view of the first direction-scattering light receiving chamber 30.
A first photodiode 33 is provided in the first direction-scattering light receiving chamber 30 for receiving the first direction-scattering light formed by scattering the incident light in the detection chamber 50 and converting it into a first electric signal.
A second photodiode is disposed in the second direction scattered light receiving chamber 40, and is configured to receive the second direction scattered light formed by scattering the incident light in the detection chamber 50, and convert the second direction scattered light into a second electrical signal.
A first parallel hemispherical mirror 31 and a first condensing hemispherical mirror 32 are sequentially provided in the first direction-scattered light receiving chamber 30 along a propagation path of the first direction-scattered light, and the first direction-scattered light sequentially passes through the first parallel hemispherical mirror 31 and the first condensing hemispherical mirror 32, is condensed into a light spot, and is received by the first photodiode 33.
That is, the first parallel hemispherical mirror 31 forms the first direction scattered light into parallel light, the first condensing hemispherical mirror 32 condenses the parallel light into a spot at the first photodiode 33, and the first photodiode 33 converts the optical signal into the first electrical signal.
One end of the first direction-scattering light receiving chamber 30 is provided with a first signal processor 34 for receiving the first electric signal generated by the first photodiode 33.
The second direction scattered light receiving chamber 40 is not shown in detail, and a second parallel hemispherical mirror and a second converging hemispherical mirror are sequentially disposed on a propagation path of the scattered light along the second direction in the second direction scattered light receiving chamber 40, and the scattered light along the second direction sequentially passes through the second parallel hemispherical mirror and the second converging hemispherical mirror, is converged into a light spot, and is received by the second photodiode.
That is, the second parallel hemispherical mirror forms the scattered light in the second direction into parallel light, the second light converging hemispherical mirror converges the parallel light into a light spot at the second photodiode, and the second photodiode converts the optical signal into the second electrical signal.
One end of the second direction-scattering light receiving chamber 40 is provided with a second signal processor 41 for receiving a second electric signal generated by a second photodiode.
The aerosol concentration detection device also comprises a control center, wherein the control center reads, analyzes and calculates the first electric signal and the second electric signal to obtain the basic physical properties and the mass concentration of the aerosol.
The incident light can be effectively processed and detected by utilizing a simple optical principle through the optical element in each light chamber, and the device has a simple and compact structure and low cost.
In some embodiments of the present application, diffuse scattered light is formed in the detection chamber 50 when the position of the light source 11 changes, referring to fig. 2, at this time, the position of the light source 11 may be adjusted in two dimensions horizontally and vertically by the light source adjusting seat 15, so that the influence of the diffuse scattered light in the detection chamber on the first signal processor 34 and the second signal processor 41 is reduced to a minimum.
Example III
The embodiment discloses an aerosol concentration detection system, which comprises an aerosol concentration detection device disclosed in the second embodiment.
Referring to fig. 1, it further includes a sheath flow branch 60 and a negative feedback regulation branch 70.
The sheath flow branch 60 is communicated with the air inlet 51 of the detection chamber 50, and is used for generating sheath air flow to form a package for aerosol flowing into the detection chamber 50, so that the aerosol is prevented from dispersing in the detection chamber 50, and the detection effect and the detection accuracy are further improved.
Referring to fig. 2, a portion of the gas flows into the sheath flow branch 60 through the outlet nozzle 54, flows through the sheath flow branch 60 and then flows into the detection chamber 50 through the inlet nozzle 55 to form a package for the sample gas entering the detection chamber 50.
The negative feedback regulating branch 70 is communicated with the air outlet 52 of the detecting chamber 50, and comprises an air pump 71, an air pump flow meter 72 and an air pump filter 73, wherein a power source for providing constant flow is used for pumping aerosol to be detected, and the air pump 71 and the air pump flow meter 72 at the rear end are protected from pollution by the air pump filter 73.
In some embodiments of the present application, after the aerosol enters the air inlet 51 of the detection chamber, a portion of the aerosol enters the sheath air branch 60, and another portion of the aerosol enters the detection chamber 50 as a sample gas.
The sheath gas branch 60 is provided with a filter 61 and a flowmeter 62, the filter 61 filters aerosol in the sheath gas branch to obtain clean gas, and the clean gas is used for wrapping the sample gas.
The flow meter 62 is used to measure the gas flow into the sheath flow branch 60 for calculating the sample gas volume during the tracing of the post filter weighing method.
In some embodiments of the present application, clean gas passing through the filter 61 and the flow meter 62 is used to generate a sheath gas flow to form a package for aerosol flowing into the detection chamber 50, and another part is used as a shielding gas to flow into the light source chamber 10, the light trap chamber 20, and the scattered light receiving chambers to protect the optical elements.
Specifically, referring to fig. 2 and 3, a light source protection air inlet nozzle 14 is provided on the light source chamber 10, a light trap protection air inlet nozzle 23 is provided on the light trap chamber 20, a lens protection air inlet nozzle 35 is provided on each scattered light receiving chamber, and a part of clean gas enters the corresponding light chamber through the air inlet nozzle to protect the light source, the light trap and the scattered light receiving chamber from being polluted.
The following experiments were performed using the aerosol concentration detection system, specifically as follows:
experiment one
Experimental instrument: 45-degree and 90-degree bidirectional photometer measurement system (light source adopts 650nm incident light), TSI 8130 automatic filter material tester and one ten thousandth balance.
The experimental steps are as follows: generating oily aerosol (generating liquid adopts paraffin oil) by using a TSI 8130 automatic filter material tester, and changing the median particle size of the aerosol by changing generating pressure; and then, measuring the oily aerosol by using a 45-90-degree bidirectional photometer measuring system to obtain a group of measurement data, acquiring and weighing by using a filter membrane to obtain a group of weighing data, and calculating mass concentration errors.
Experimental data:
conclusion of experiment: when the pressure-changed aerosol is measured (the median particle diameter of the aerosol is changed) by using a 45-90-degree bidirectional photometer measuring system (the light source adopts 650nm incident light), the error between the test data and the filter membrane weighing data can be still kept within 10% without modifying the system parameters.
Experiment two
Experimental instrument: 60-degree and 120-degree bidirectional photometer measurement system (the light source adopts 650nm incident light), TSI 8130 automatic filter material tester and one ten thousandth balance.
The experimental steps are as follows: generating salt aerosol (generating liquid adopts 2% NaCl solution) by using a TSI 8130 automatic filter material tester, and changing the median particle size of the aerosol by changing generating pressure; and then a 60-DEG plus 120-DEG bidirectional photometer measurement system is used for measuring the salt aerosol to obtain a group of measurement data, and a filter membrane is used for collecting and weighing to obtain a group of weighing data, and the mass concentration error is calculated.
Experimental data:
conclusion of experiment: when the pressure-changed aerosol is measured (the median particle diameter of the aerosol is changed) by using a 60-120-degree bidirectional photometer measuring system (the light source adopts 650nm incident light), the error between the test data and the filter membrane weighing data can be still kept within 10% without modifying the system parameters.
The experiment proves that the error of the device is less than 10 percent when the device measures the concentration of aerosol, compared with the concentration tested by a gravimetric method. Meanwhile, when the diameter of the aerosol in counting is changed, the accuracy of aerosol mass concentration measurement is still ensured.
The system can also be adapted to a specific aerosol particle size range by varying the wavelength of the light source.
In the description of the above embodiments, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (6)
1. An aerosol concentration detection system, characterized in that,
absorbing incident light passing straight through the detection chamber with an extinction element, and preventing the incident light not absorbed by the extinction element from returning to the detection chamber with a diaphragm;
utilizing a plurality of photodiodes to respectively receive multi-angle scattered light formed by scattering of incident light in the detection chamber and convert the multi-angle scattered light into an electric signal;
analyzing and calculating a plurality of the electric signals to obtain the concentration of the aerosol;
the detection system comprises an aerosol concentration detection device, a sheath gas branch and a negative feedback regulation branch;
the detection device includes:
a detection chamber through which an aerosol flows;
the light source chamber is used for irradiating incident light to the detection chamber, and a light source diaphragm is arranged in the light source chamber;
an optical trap chamber which is arranged opposite to the light source chamber, wherein incident light reaches the optical trap chamber through the detection chamber, and an extinction element is arranged in the optical trap chamber;
the scattered light receiving chambers are arranged between the light source chamber and the light trap chamber, the included angles between each scattered light receiving chamber and the light trap chamber are different, and each scattered light receiving chamber is internally provided with a photodiode for receiving scattered light formed by scattering of incident light in the detection chamber and converting the scattered light into an electric signal;
the sheath gas branch is communicated with the air inlet of the detection chamber and is used for generating clean sheath gas flow to form a package for aerosol flowing into the detection chamber, after the aerosol enters the air inlet of the detection chamber, one part of the aerosol enters the sheath gas branch, the other part of the aerosol enters the detection chamber, one part of clean gas in the sheath gas branch is used for generating sheath gas flow to form a package for aerosol flowing into the detection chamber, and the other part of clean gas flows into the light source chamber, the light trap chamber and the scattered light receiving chamber to protect optical elements;
and the negative feedback regulating branch is communicated with the air outlet of the detection chamber.
2. The aerosol concentration detection system of claim 1, wherein,
receiving scattered light in a first direction formed by scattering of incident light in the detection chamber by using a first photodiode, and converting the scattered light into a first electric signal;
receiving scattered light in a second direction formed by scattering of incident light in the detection chamber by using a second photodiode, and converting the scattered light into a second electric signal;
and analyzing and calculating the first electric signal and the second electric signal to obtain the concentration of the aerosol.
3. The aerosol concentration detection system of claim 2, wherein,
the included angle between the first direction and the direct propagation direction of the incident light in the detection chamber is 90 degrees, and the included angle between the second direction and the direct propagation direction of the incident light in the detection chamber is 45 degrees;
alternatively, the first direction and the direct propagation direction of the incident light in the detection chamber have an included angle of 120 degrees, and the second direction and the direct propagation direction of the incident light in the detection chamber have an included angle of 60 degrees.
4. The aerosol concentration detection system of claim 2, wherein,
forming parallel light by using a first parallel hemispherical mirror and converging the parallel light into a light spot at the first photodiode by using a first condensing hemispherical mirror;
and utilizing a second parallel hemispherical mirror to scatter light in the second direction to form parallel light, and utilizing a second light converging hemispherical mirror to converge the parallel light into a light spot at the second photodiode.
5. The aerosol concentration detection system of claim 4, wherein,
receiving the first electric signal generated by the first photodiode by using a first signal processor and feeding back the first electric signal to a control center;
receiving the second electric signal generated by the first photodiode by using a second signal processor and feeding back the second electric signal to a control center;
the control center analyzes and calculates the first electric signal and the second electric signal.
6. The aerosol concentration detection system of claim 2, wherein,
utilizing a cylindrical mirror to form flat in-line light from incident light emitted by a light source before entering the detection chamber;
stray light in incident light is eliminated by a light source diaphragm.
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