CN116754444A - Miniature handheld nano-grade particulate matter detection device and detection method - Google Patents
Miniature handheld nano-grade particulate matter detection device and detection method Download PDFInfo
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- 239000013618 particulate matter Substances 0.000 title abstract description 15
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- 229910052751 metal Inorganic materials 0.000 claims abstract description 104
- 239000002184 metal Substances 0.000 claims abstract description 104
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- 239000012716 precipitator Substances 0.000 claims abstract description 31
- 238000009833 condensation Methods 0.000 claims abstract description 26
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- 239000011882 ultra-fine particle Substances 0.000 claims abstract description 25
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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
- G01N15/02—Investigating particle size or size distribution
- G01N15/0205—Investigating particle size or size distribution by optical means
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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
- G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
- G01N15/0612—Optical scan of the deposits
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Abstract
The invention relates to a miniature handheld nano-scale particulate matter detection device and a detection method. The device comprises an aerosol photo-charger, an aerosol precipitator and an aerosol mixed condensation particle counter; the aerosol photoinduced charger comprises a charging shell, a UVC light-emitting device and a metal electronic collecting net; the aerosol precipitator includes a precipitator body and an electrically insulating gasket; the precipitator body comprises a first metal plate, a metal disc and a second metal plate; a first gap is reserved between the first metal plate and the metal disc, and the gap and the inner wall of the electric insulation gasket form a first flow chamber; a second gap is reserved between the second metal plate and the metal disc, and the second gap and the inner wall of the electric insulation gasket form a second flow chamber; the aerosol mixed condensation particle counter comprises an aerosol growth module and a photoelectric detection module. The invention has the characteristics of simple structure, small volume and the like of the measuring equipment, and can realize direct measurement and large-scale distribution measurement of the particle size spectrum of the low-concentration ultrafine particles.
Description
Technical Field
The invention relates to the technical field of ultra-fine particulate matter exposure detection, in particular to a miniature handheld nano-scale particulate matter detection device and a detection method.
Background
The nano-particles in the atmosphere are one of the important factors for the pollution of the atmospheric environment such as haze. The national emphasis laboratory of ecological environment research center environmental chemistry and ecotoxicology found that exogenous ultrafine particles were found in blood and pleural effusions of the general population. After nasal breathing, the ultrafine particles can be deposited on tissues and organs such as whole lung, nose, pharynx, larynx, bronchus, trachea, alveoli and brain. Although a great deal of epidemiological and toxicological studies have linked exposure to nanoscale particulate matter to adverse health effects, the important indicators of both particulate matter quantity and particle size distribution concentration of these toxic aerosols have not been directly regulated.
Particles in the submicron and nanometer range are present in the exhaust gases of different combustion sources, chemical processes and aerosol reactors. Such as exhaust gases from diesel and jet engines, emissions from coal-fired power plants and welding fumes, which nano-species are defined as environmental pollution. In addition, with the development of the nano-technology industry and the semiconductor industry, nanoparticles of different materials are synthesized in chemical reactors for various modern industrial applications. At the same time, the nano-particles affect the semiconductor process level, so that the monitoring of the particle size distribution of the nano-particles in a semiconductor production workshop is particularly important.
At present, commercial detection instruments of aerosol mainly comprise a laser scattering intensity detection method based on a light scattering principle, an aerodynamic particle size detection method based on kinematic properties, an electric mobility detection method based on particle electric mobility and the like. The aerodynamic and light scattering methods are mostly suitable for measuring micron-sized particles, and instruments based on the principle of electromigration are suitable for measuring nano-sized and submicron-sized particles. However, the current instrument based on the principle of electric mobility has larger body size and higher cost, and is not suitable for portable measurement and large-range point distribution measurement. Meanwhile, a charge module of the instrument based on the electric mobility principle mostly adopts diffusion charge, corona charge and the like, ozone is easy to generate in the discharging process, and a tungsten needle needs to be replaced periodically; the particle collection module adopts a Faraday cup electrometer, and is not suitable for measurement in a low-concentration environment.
Therefore, it is necessary to develop a portable ultra-fine particulate particle size spectrometer with low detection lower limit, low cost, miniaturized nano-scale.
Disclosure of Invention
The invention aims to provide a miniature handheld nano-grade particulate matter detection device and a detection method, which can solve the defects in the prior art, have the characteristics of simple structure, small volume, low detection lower limit and the like of measurement equipment, and can realize direct measurement and large-scale distribution measurement of the particle size spectrum of ultrafine particulate matters.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect of the present invention, a miniature handheld nanoscale particulate matter detection device is disclosed.
A miniature handheld nano-scale particulate matter detection device comprises an aerosol photo-charger, an aerosol precipitator and an aerosol mixed condensation particle counter which are sequentially arranged;
the aerosol photoinduced charger comprises a charging shell, a UVC (ultraviolet light emitting) device and a metal electron collecting net, wherein the UVC light emitting device and the metal electron collecting net are arranged on the charging shell;
the aerosol precipitator comprises a precipitator main body and an electric insulation gasket sleeved on the outer side of the precipitator main body; the precipitator main body comprises a first metal plate, a metal disc and a second metal plate which are sequentially arranged; a plurality of through holes are formed in the metal disc; a first gap is reserved between the first metal plate and the metal disc, and the gap and the inner wall of the electric insulation gasket form a first flow chamber; a second gap is reserved between the second metal plate and the metal disc, and the second gap and the inner wall of the electric insulation gasket form a second flow chamber; the through hole is used for communicating the first flow chamber with the second flow chamber;
the aerosol mixed condensation particle counter comprises a particle growth module and a photoelectric detection module which are sequentially arranged.
Further, the charging shell is provided with a charging aerosol air inlet and a charging aerosol air outlet which are coaxially arranged;
the charging shell is provided with sealing rubber rings at two sides of the UVC light-emitting device;
the lower end of the charging shell is in a 45-degree slope shape.
Further, the light emitted by the UVC light emitting device is perpendicular to the flowing direction of the aerosol.
Further, the metal electron collecting net is fixed in the charged shell, and is respectively located at two sides of the aerosol airflow with the UVC luminous device.
Further, an inlet pipe is arranged on the first metal plate and communicated with the inside of the charging shell;
and an outlet pipe is arranged on the second metal plate and connected with the aerosol mixed condensation particle counter.
Further, the metal disc is connected with high-voltage electricity, the first metal plate and the second metal plate are grounded or biased to separate electric potentials relative to the metal disc, and an electric field is respectively established in the first flow chamber and the second flow chamber to form a separate electric field which is not commonly grounded with other electronic equipment of the instrument.
Further, the particle growth module comprises an aerosol growth chamber housing and a liquid storage tank communicated with the aerosol growth chamber housing; the outer wall of the aerosol growth cavity shell is provided with a heating sleeve, a refrigerating sleeve and a heat insulation sleeve; the shell of the aerosol growth cavity is provided with a first aerosol air inlet, an aerosol air outlet and a working solution inlet; the first aerosol air inlet is connected with the outlet of the aerosol precipitator; the working solution inlet is connected with the liquid storage tank; the heating sleeve is used for heating the working fluid to be changed into steam; the refrigeration suite is used for reducing the temperature of aerosol; the heat insulation sleeve is used for insulating heat and performing heat insulation mixing on hot steam and cold aerosol; the liquid storage tank is used for storing working liquid;
the photoelectric detection module comprises a photoelectric detection cavity, and a photoelectric emitter and a photoelectric detector which are arranged on the photoelectric detection cavity; and a second aerosol air outlet is formed in the photoelectric detection cavity.
Further, the device also comprises a main control module;
the main control module comprises a controller, a vacuum pump, a scanning voltage module, a power supply module and a photoelectric signal processing module;
the output end of the controller is respectively connected with the input end of the scanning voltage module and the input end of the vacuum pump;
the output end of the scanning voltage module is respectively connected with the first metal plate, the second metal plate and the metal disc;
the photoelectric signal processing module is connected with the photoelectric detector;
the vacuum pump is respectively connected with the first aerosol air outlet and the second aerosol air outlet.
In a second aspect of the present invention, a detection method of the above-described detection device is disclosed.
The method comprises the following steps:
(1) The aerosol-like gas enters the aerosol photo-charger at a flow rate.
(2) The UVC light-emitting device in the aerosol photoinduced charger emits UVC light, the UVC light collides with the aerosol to enable the aerosol to lose electrons, and the escaped electrons are collected by the metal electron collecting net, so that superfine particles in the aerosol sample gas are positively charged, and charged particles are obtained.
(3) Charged particles are introduced into a first flow chamber of the aerosol precipitator, the charged particles move radially outwardly, pass through holes in the metal disc, enter into a second flow chamber and radially converge at an outlet pipe; when a fixed electric field is established in the first flow chamber or the second flow chamber, the track of the charged particles deflects, the charged particles meeting the set electric mobility are deposited on the first metal plate or the second metal plate, and the rest of the charged particles leave the aerosol precipitator partially or completely and enter the aerosol mixed condensation particle counter.
(4) Ultrafine particles entering the aerosol mixed condensation particle counter are mixed with working solution steam which is cooled by a refrigeration sleeve and heated by a heating sleeve, so that condensation and growth of the ultrafine particles are realized; the ultra-fine particles after condensation and growth pass through the photoelectric detection cavity and finally leave from the aerosol air outlet. The working solution is stored in the liquid storage tank, the working solution is heated by the heating sleeve to form working solution steam, and ultrafine particles (aerosol) and the working solution steam are mixed at the T-shaped opening of the shell of the aerosol growth cavity. The hot working fluid vapor will start to grow when mixed with the cold particulate matter, and the hot vapor will wrap the particulate matter, thereby making the volume of the particulate matter grow, reaching the size that the photodetection module can detect.
(5) When the coagulated and grown ultrafine particles pass through the photoelectric detection cavity, the photoelectric detector can generate pulses, the pulses are processed by the photoelectric signal processing module to obtain the ultrafine particle quantity with corresponding particle size under corresponding scanning voltage, and the concentration of the ultrafine particles with the particle size is determined.
Further, the method further comprises: under the condition that the flow speed of the sample gas flow is stable, the scanning voltage between the metal disc and the first metal plate and between the metal disc and the second metal plate is changed, the concentration of the superfine particles under different particle sizes is detected in a grading mode, and a particle size spectrum is drawn according to the concentration of the superfine particles under different particle sizes.
Compared with the prior art, the invention has the advantages that:
(1) Compared with the traditional corona discharge, the micro aerosol photoinduced charger has higher aerosol charge efficiency below 20nm by adopting a UVC light source irradiation method, and has stable operation and difficult ozone generation. The diffusion charge rate under soft x-ray irradiation is improved compared to UV (-5 eV) irradiation. However, the high cost and limited lifetime of soft x-ray sources makes them difficult to use.
(2) Compared with the traditional electromigration detection method, the particle loss is reduced, and the lower limit of the detection concentration of the superfine particles is greatly improved. The detection device provided by the invention has a simple structure and a small volume, and can realize the grading detection of the ultrafine particles with the small particle size range of 10 nm-200 nm. The removal of the sheath gas circulation reduces the number of the particle size classification channels, but has little influence, because the particle size classification channels are not needed too much under the condition of lower concentration, but the removal of the sheath gas circulation greatly reduces the loss of the detected particles, thereby improving the detection sensitivity of the ultrafine particles under the low concentration environment.
(3) Compared with the traditional cylindrical electromigration detection method, the flat plate electromigration detection method is simpler in structure, lighter in size and higher in detection effect and accuracy of detection results.
(4) Compared with the traditional heat conduction type condensation particle growth method, the method provided by the invention has the advantages that cold particles are mixed with excessive hot and wet working fluid steam, the rapid and nearly adiabatic mixing is promoted by making the mixing area highly turbulent, so that aerosol can rapidly grow in a small space, and the diffusion loss is small. Turbulent mixing can achieve ingredient uniformity quickly with little particulate diffusion loss. With this method an increase in particle size of 10 microns can be achieved in less than 100 milliseconds.
(5) The nano-scale particulate matter detection device has the characteristics of low cost, small volume and the like, and is suitable for point distribution monitoring in various occasions. The invention adopts the photo-induced charge device, the aerosol precipitator and the aerosol mixed type condensation particle counter integrated ultra-fine particle detection particle size spectrometer, and can carry out particle size distribution measurement on ultra-fine particles in a low concentration environment due to the adoption of an optical detection method.
Drawings
FIG. 1 is a schematic diagram of a detecting device according to the present invention;
FIG. 2 is a top view of a metal disc of the present invention;
FIG. 3 is a flow chart of the detection method of the present invention.
Wherein:
1. the device comprises an aerosol photoinduced charger, 111, a charger aerosol gas inlet, 112, a charger aerosol gas outlet, 12, a charger cover plate, 13, a charger housing, 14, a UVC lighting device fixing frame, 15, a UV lighting device, 16, a metal electronic collecting net, 2, a micro disk aerosol precipitator, 21, a first metal plate, 221, an inlet pipe, 222, an outlet pipe, 23, an electric insulation gasket, 24, a first flow chamber, 25, a porous metal disk, 26, a second flow chamber, 27, a second metal plate, 3, an aerosol mixed condensation particle counter, 311, an aerosol growth cavity housing, 312, a photoelectric detection cavity, 32, a refrigeration kit, 33, a photoelectric detector, 34, a photoelectric emitter, 35, a heating kit, 36, a liquid storage tank, 37, an insulation kit, 38, a particle growth module, 39, a photoelectric detection module, 4, a main control module, 41, a controller, 42, a vacuum pump, 43, a scanning voltage module, 44 and a power module.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
the miniature handheld nano-scale particle detection device shown in fig. 1 comprises a miniature aerosol photo-charger 1, a miniature disc-type aerosol precipitator 2, an aerosol mixed condensation particle counter 3 and a main control module 4. The detection device can ensure the detection precision of 10-200nm nano particles, simultaneously can greatly reduce the volume and weight of the whole equipment, ensures the miniaturization of the nano particle detector, can realize the handheld design, and can realize the integration into other environment monitoring instruments in a module form.
The aerosol charger 1 is a miniature aerosol photo-charger, and comprises a charging housing 13 and a UV light emitting device 15. The charger cover 12 is provided with an aerosol inlet 111. The sample gas flow flows into the aerosol photoinduced charger 1 from the aerosol gas inlet 111, the metal electron collecting net 16 is fixed in the charging shell 13 and is respectively positioned at two sides of the aerosol gas flow with the UVC light emitting devices 15, the UVC light emitting devices 15 in the aerosol photoinduced charger 1 emit UVC light rays, electrons are lost by the aerosol due to collision of the UVC light rays, and the escaped electrons are collected by the electron collecting metal net 16 so that superfine particles in the sample gas are positively charged, so that charged particles are obtained; the lower end of the charging shell 13 is in a 45-degree slope shape, so that the loss of particulate matters can be effectively reduced.
The aerosol precipitator 2 is a mini-disc aerosol precipitator comprising a first metal plate 21, a second metal plate 27, a metal disc 25 and an electrically insulating gasket 23. The porous metal plate 25 is sandwiched between the first metal plate 21 and the second metal plate 27 which are symmetrically arranged, and is sleeved outside the middle section of the metal structure formed by the first metal plate 21, the metal plate 25 and the second metal plate 27 by using an electric insulating gasket 23. There is a gap between the first metal plate 21 and the metal plate 25, and a gap between the second metal plate 27 and the metal plate 25. The electrically insulating gasket 23 forms two identical flow chambers with the two gaps, respectively: a first flow chamber 24 and a second flow chamber 26. The metal plate 25 is provided with a plurality of through holes for connecting the first flow chamber 24 and the second flow chamber 26. The charged aerosol-like gas is introduced into the first flow chamber 24 through an inlet pipe 221 provided in the middle of the first metal plate 21. The outlet tube 222 connected to the second metal plate 27 serves as an aerosol outflow opening. The voltage may be applied by a high voltage wire connected to the outer edge of the middle porous metal disc 25. The first metal plate 21 and the second metal plate 27 may be electrically grounded or biased to separate potentials with respect to the intermediate metal plate 25 to establish separate electric fields in either flow chamber. Aerosol enters the aerosol precipitator from inlet pipe 221, moves radially outwardly, passes through the through holes in the metal disc, and converges radially into outlet pipe 222. When a fixed electric field is established across either chamber, the trajectories of the charged particles will deflect and all particles with sufficient electric mobility will deposit on the first 21 and second 27 metal plates, while those with lower mobility will partially or fully escape and leave the aerosol precipitator.
The aerosol hybrid condensation particle counter 3 comprises a particle growth module 38 and a photo detection module 39. The particle growth module 38 includes an aerosol growth chamber housing, a heating sleeve 35, a cooling sleeve 32, a liquid reservoir 36, and a photodetection chamber 312 mounted to the aerosol growth chamber housing 311, and a photodetector 33 and a photodetector 34 mounted to the photodetection chamber 312. The classified particles enter the aerosol mixed condensation particle counter 3, are cooled by the refrigeration suite 32 and then are mixed with working fluid steam heated by the heating suite 35, condensation growth of ultrafine particles is achieved, the particles enter the photoelectric detection module 39 after growth, the photoelectric emitter 34 emits light, part of the light is shielded by the growing particles, the rest of the light is received by the photoelectric detector 33, the laser detector 33 on the photoelectric detection module 39 is connected with the main control module 4, and the photoelectric signal processing module of the main control module 4 receives photoelectric signals. The main control module 4 includes a controller 41, a power supply module 44, a scan voltage module 43, and a vacuum pump 42. The output end of the controller 41 is respectively connected with the input end of the high-voltage constant-current module 45, the input end of the scanning voltage module 43 and the input end of the vacuum pump 42; the output end of the power module 44 is connected with the UV emitting device 15; the scanning voltage module 43 is connected with the perforated metal disc 25, the first metal plate 21 and the second metal plate 27; the output end of the vacuum pump 42 is connected with a sample gas outlet.
As shown in fig. 3, the present invention further relates to a detection method of the micro handheld nano-sized particulate matter detection device, which comprises the following steps:
(1) The controller 41 controls the sample gas flow to enter the micro aerosol photo-charger 1 through the radial inlet tube 111 air inlet at a certain flow rate by the vacuum pump 42.
(2) The power module 44 controls the UVC light emitting device 15 in the aerosol photo-charger to emit UVC light, and the collision between the UVC light and the aerosol can cause the aerosol to lose electrons, and the escaped electrons are collected by the electron collecting metal net 16, so that the ultra-fine particles in the sample gas are positively charged, and charged particles are obtained.
(3) The dotted aerosol is introduced into the first flow chamber 24 by the central tube 221 of the top plate of the mini-disc aerosol precipitator 2 with the charged aerosol-like gas, and the classification voltage may be applied by a high voltage wire connected to the outer edge of the intermediate metal disc 25. The first metal plate 21 and the second metal plate 27 may be electrically grounded or biased to separate potentials with respect to the middle plate to establish separate electric fields in either flow chamber. Charged particles enter the device from a central inlet tube 221, move radially outward, pass through the orifice, and radially converge to an opposite central outlet tube 222. When a fixed electric field is established across either chamber, the trajectories of the charged particles are deflected. All particles with sufficient electrical mobility will deposit on the plate, while those with lower mobility will partially or fully escape and leave the mini-disc aerosol precipitator 2.
(4) Ultrafine particles entering the aerosol mixed type condensation particle counter 3 from the micro disc type aerosol precipitator 2 are cooled by the refrigeration sleeve 32 and then mixed with working fluid steam heated by the heating sleeve 35, so that condensation and growth of ultrafine particle particles are realized, and the particles enter the photoelectric detection module after growth. The photo-emitter 34 emits light, part of which is blocked by the growing particles and the remaining light is received by the photo-detector 33. The laser detector 33 on the photoelectric detection module is connected with the main control module 4, and the photoelectric signal processing module of the main control module 4 receives the photoelectric signal and processes the photoelectric signal.
(5) Under the condition that the flow rate of the sample gas flow is stable, the controller 41 changes the scanning voltage between the metal disc 25 with holes and the first metal plate 21 and the second metal plate 27 through the scanning voltage module 43, and detects the concentration of the ultrafine particles under different particle sizes in a grading manner, and draws a particle size spectrum according to the concentration of the ultrafine particles under different particle sizes.
The detection device consists of an aerosol photo-charger, an aerosol precipitator and a micro-current detection module aerosol mixed condensation particle counter, and no similar product exists in the market at present. The charging module of the current mainstream particle size spectrometer mostly adopts soft x-ray charging, diffusion charging and corona discharge, compared with the traditional corona discharge, the UVC irradiation method adopted by the invention has higher charging efficiency of aerosol below 20nm, stable operation and difficult ozone generation. The diffusion charge rate under soft x-ray irradiation is improved compared to UV (-5 eV) irradiation. However, the high cost and limited lifetime of soft x-ray sources makes them difficult to use. The current grading module of the particle size spectrometer mostly adopts an electromigration analyzer with sheath gas circulation, and has low penetration efficiency and large particle loss, and cannot be suitable for aerosol grading detection in a low-concentration environment. The particle detection module of the current low-concentration particle size spectrometer mostly uses a heat conduction type condensation particle counter, the particle growth speed of the type instrument is slower, so that the particle detection module is larger in size and cannot be subjected to microminiaturization design. In conclusion, the invention can realize the monitoring of the particle size distribution of the aerosol with the small particle size range of 10nm to 200nm under the low concentration environment on the premise of microminiaturization design.
The above examples are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the scope of protection defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (10)
1. A miniature hand-held nano-particle detection device is characterized in that,
the device comprises an aerosol photo-charger, an aerosol precipitator and an aerosol mixed condensation particle counter which are sequentially arranged;
the aerosol photoinduced charger comprises a charging shell, a UV (ultraviolet) light emitting device and a metal electronic collecting net, wherein the UV light emitting device and the metal electronic collecting net are arranged on the charging shell;
the aerosol precipitator comprises a precipitator main body and an electric insulation gasket sleeved on the outer side of the precipitator main body; the precipitator main body comprises a first metal plate, a metal disc and a second metal plate which are sequentially arranged; a plurality of through holes are formed in the metal disc; a first gap is reserved between the first metal plate and the metal disc, and the gap and the inner wall of the electric insulation gasket form a first flow chamber; a second gap is reserved between the second metal plate and the metal disc, and the second gap and the inner wall of the electric insulation gasket form a second flow chamber; the through hole is used for communicating the first flow chamber with the second flow chamber;
the aerosol mixed condensation particle counter comprises a particle growth module and a photoelectric detection module which are sequentially arranged.
2. The detecting device according to claim 1, wherein,
the charging shell is provided with a charging aerosol air inlet and a charging aerosol air outlet which are coaxially arranged;
the charging shell is provided with sealing rubber rings at two sides of the UVC light-emitting device;
the lower end of the charging shell is in a 45-degree slope shape.
3. The detecting device according to claim 1, wherein,
the light emitted by the UVC light emitting device is perpendicular to the flowing direction of the aerosol.
4. The detecting device according to claim 1, wherein,
the metal electron collecting net is fixed in the charged shell and is respectively positioned at two sides of the aerosol airflow with the UVC luminous device.
5. The detecting device according to claim 1, wherein,
an inlet pipe is arranged on the first metal plate and communicated with the inside of the charging shell;
and an outlet pipe is arranged on the second metal plate and connected with the aerosol mixed condensation particle counter.
6. The detecting device according to claim 1, wherein,
the metal disc is connected with high-voltage power;
the first metal plate and the second metal plate are grounded or biased to separate electric potentials relative to the metal plate, and an electric field is established in the first flow chamber and the second flow chamber respectively to form a separate electric field which is not commonly grounded with other electronic equipment of the instrument.
7. The detecting device according to claim 1, wherein,
the particle growth module comprises an aerosol growth cavity shell and a liquid storage tank communicated with the aerosol growth cavity shell; the outer wall of the aerosol growth cavity shell is provided with a heating sleeve, a refrigerating sleeve and a heat insulation sleeve; an aerosol air inlet, a first aerosol air outlet and a working solution inlet are formed in the shell of the aerosol growth cavity; the first aerosol air inlet is connected with the outlet of the aerosol precipitator; the working solution inlet is connected with the liquid storage tank; the heating sleeve is used for heating the working fluid to be changed into steam; the refrigeration suite is used for reducing the temperature of aerosol; the heat insulation sleeve is used for insulating heat and performing heat insulation mixing on hot steam and cold aerosol; the liquid storage tank is used for storing working liquid;
the photoelectric detection module comprises a photoelectric detection cavity, and a photoelectric emitter and a photoelectric detector which are arranged on the photoelectric detection cavity; and a second aerosol air outlet is formed in the photoelectric detection cavity.
8. The detecting device according to claim 7, wherein,
the device also comprises a main control module;
the main control module comprises a controller, a vacuum pump, a scanning voltage module, a power supply module and a photoelectric signal processing module;
the output end of the controller is respectively connected with the input end of the scanning voltage module and the input end of the vacuum pump;
the output end of the scanning voltage module is respectively connected with the first metal plate, the second metal plate and the metal disc;
the photoelectric signal processing module is connected with the photoelectric detector;
the vacuum pump is respectively connected with the first aerosol air outlet and the second aerosol air outlet.
9. The detection method of the detection apparatus according to any one of claims 1 to 8, characterized in that the method comprises:
(1) Aerosol sample gas enters an aerosol photo-charger at a certain flow rate;
(2) The UVC light-emitting device in the aerosol photoinduced charger emits UVC light, the UVC light collides with the aerosol to cause the aerosol to lose electrons, and the escaped electrons are collected by the metal electron collecting net, so that superfine particles in the aerosol sample gas are positively charged to obtain charged particles;
(3) Charged particles are introduced into a first flow chamber of the aerosol precipitator, the charged particles move radially outwardly, pass through holes in the metal disc, enter into a second flow chamber and radially converge at an outlet pipe; when a fixed electric field is established in the first flow chamber or the second flow chamber, the track of the charged particles deflects, so that the charged particles with the set electric mobility are deposited on the first metal plate or the second metal plate, and the rest of the charged particles leave the aerosol precipitator partially or completely and enter the aerosol mixed condensation particle counter;
(4) Ultrafine particles entering the aerosol mixed condensation particle counter are mixed with working solution steam which is cooled by a refrigeration sleeve and heated by a heating sleeve, so that condensation and growth of the ultrafine particles are realized;
(5) When the coagulated and grown ultrafine particles pass through the photoelectric detection cavity, the photoelectric detector can generate pulses, the pulses are processed by the photoelectric signal processing module to obtain the ultrafine particle quantity with corresponding particle size under corresponding scanning voltage, and the concentration of the ultrafine particles with the particle size is determined.
10. The method of claim 9, wherein,
the method further comprises the steps of:
under the condition that the flow speed of the sample gas flow is stable, the scanning voltage between the metal disc and the first metal plate and between the metal disc and the second metal plate is changed, the concentration of the superfine particles under different particle sizes is detected in a grading mode, and a particle size spectrum is drawn according to the concentration of the superfine particles under different particle sizes.
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| CN202310549393.0A CN116754444A (en) | 2023-05-16 | 2023-05-16 | Miniature handheld nano-grade particulate matter detection device and detection method |
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| CN202310549393.0A CN116754444A (en) | 2023-05-16 | 2023-05-16 | Miniature handheld nano-grade particulate matter detection device and detection method |
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