CN106644856B - Miniaturized flat plate device for rapidly measuring particle size distribution of fine particles and measuring method thereof - Google Patents

Abstract

The invention provides a miniaturized flat panel device for quickly measuring the particle size distribution of fine particles, which includes a unipolar flat panel charging module mainly composed of a first upper panel, a first lower panel, a discharge chamber, a discharge needle and a conductive porous plate , a flat-panel detection module mainly composed of the second upper panel, the second lower panel, separate electrodes, a multi-port array voltage source, sensitive electrodes and an electrometer, mainly composed of a controller, a unipolar high voltage source and its control circuit, and a scanning voltage A micro-current signal processing and voltage control module composed of a control circuit, a micro-current detection and processing circuit, a vacuum pump and its driving circuit, a memory and a display. The invention also provides a measurement method of a flat plate device for miniaturization and rapid measurement of the particle size distribution of fine particles. The invention has a simple structure, and provides technical support for the miniaturized, rapid and real-time measurement of the particle size distribution of outdoor atmospheric fine particles.

Description

Miniaturized flat-panel device for rapidly measuring particle size distribution of fine particles and its measurement method

technical field

The invention relates to the technical field of fine particle detection in the atmospheric environment, in particular to a miniaturized flat panel device for rapidly measuring the particle size distribution of fine particles and a measurement method thereof.

Background technique

In recent years, with the continuous improvement of living standards and the continuous deterioration of air pollution, people have gradually turned their attention to environmental pollution, and paid more and more attention to public health, especially the particulate matter in the atmospheric environment. Although fine particulate matter is only a small component of the earth's atmospheric composition, it has an important impact on air quality and visibility. Studies have shown that the smaller the particles, the greater the harm to human health. At the same time, fine particles can float to farther places and have a larger impact range. Therefore, it is necessary to classify the particles when measuring the concentration of particles.

At present, the method of combining light scattering and aerodynamic time-of-flight measurement is widely used in the world to realize the measurement of light scattering particle size or aerodynamic particle size, such as optical particle counter and aerodynamic particle size spectrometer, but they are very It is difficult to measure atmospheric fine particles with a particle size below 300nm. For the particle size measurement of atmospheric fine particles with a particle size below 100nm, the particle size classification is mainly realized internationally through the electrical migration characteristics of charged particles in an electric field, and according to the different electrical mobility of particles with different particle sizes.

The traditional nano-scale particle classification instrument is designed with a combined measurement system of scanning electric mobility particle size spectrometer (SMPS) + Faraday cup electrometer (FCE). relatively expensive. For example, the R&D personnel of Grimm Company in Germany combined electromigration scanning with Faraday cup micro-current detection. The structure is complex and bulky, and it is not suitable for the detection of mobile pollution sources; at the same time, the existing technology generally adopts macroscopic mechanical structures. Extremely high requirements are put forward, and at the same time it is generally difficult to achieve miniaturization and real-time monitoring. For example, Professor Chen D.R. of the United States has made a great contribution to the structural size of the detection module, and the volume has been miniaturized, but the scanning of the detection module is fixed, and at the same time, the detection and measurement ratio of a single electrometer is many Parallel measurement by two electrometers is slow and has poor real-time performance, so it is not suitable for rapid measurement of particle size spectrum, such as rapid detection of particulate matter emissions from mobile pollution sources.

At present, most of the transfer tubes in common commercial particle size detection instruments adopt a cylindrical structure, which is composed of two concentric cylindrical electrodes inside and outside. The coaxiality of the electrodes is extremely high, and its small error will also lead to uneven electric field and decrease. DMA detection performance; and the smaller the electrode size, the more difficult it is to control its coaxiality accuracy, which greatly enhances the difficulty of miniaturizing the DMA transfer tube. At the same time, the charge collection device needs to use a Faraday cup, which increases the complexity, volume and cost of the system, and the key core modules of the measurement system cannot be integrated and shielded. Ultimately, the processing and assembly process of the entire measurement system is difficult, the structure is complex, the volume is large, and the cost is high.

Contents of the invention

The purpose of the present invention is to provide a flat plate device and its measurement method for quickly measuring the particle size distribution of fine particles in miniaturization, which can make up for the deficiencies of the existing measurement technology of particle size distribution of fine particles, especially solve the problem that the existing measuring equipment cannot measure quickly and in real time, Bulk, not easy to carry and other issues.

Technical scheme of the present invention is:

A miniaturized flat-panel device for quickly measuring the particle size distribution of fine particles, the device includes a unipolar flat-panel charging module, a flat-panel detection module, and a microcurrent signal processing and voltage control module;

The unipolar flat-plate charging module includes a first upper panel and a first lower panel that are parallel to each other and facing each other, discharge chambers that are evenly opened on the first upper panel and the first lower panel and vertically correspond to each other, and are arranged on the A discharge needle in the discharge chamber and a conductive porous plate for sealing the discharge chamber; a sheath gas inlet channel is formed between the first upper panel and the first lower panel;

The flat-panel detection module includes a second upper panel and a second lower panel arranged parallel to each other, a plurality of separated electrodes arranged on the second upper panel, and a plurality of voltage sources connected to the separated electrodes in one-to-one correspondence, for centralized The multi-port array voltage source of the voltage source is installed, the sensitive electrodes arranged on the second lower panel and corresponding to the separated electrodes one by one, a number of electrometers connected to the sensitive electrodes one by one, and arranged on the second upper panel and the second lower panel The exhaust gas outlet at the rear end of the panel; the second upper panel and the first upper panel are parallel to each other and form a sample gas inlet channel;

The micro-current signal processing and voltage control module includes a controller, a unipolar high-voltage source connected to the discharge needle and its control circuit, a scanning voltage control circuit connected to the multi-port array voltage source, and a micro-current detection circuit connected to the electrometer A processing circuit, a vacuum pump connected to the sheath gas inlet channel, the sample gas inlet channel and the exhaust gas outlet and its drive circuit, a memory connected to the controller and a display connected to the input terminal and the output terminal of the controller; the microcurrent The output end of the detection processing circuit is connected to the input end of the controller, and the output end of the controller is respectively connected to the input end of the unipolar high voltage source and its control circuit, the input end of the scanning voltage control circuit, and the input end of the vacuum pump and its driving circuit end.

In the miniaturized flat panel device for quickly measuring the particle size distribution of fine particles, the first upper panel, the first lower panel, the second upper panel and the second lower panel are all made of alumina ceramics; the first upper panel The distance between the first lower panel and the first lower panel is 2-6mm, the distance between the second upper panel and the second lower panel is 1-8mm, and the air inlet slit of the sample gas inlet channel is 0.5-2mm.

In the miniaturized flat-panel device for rapidly measuring the particle size distribution of fine particles, the discharge needles are in an array vertically symmetrical structure, made of tungsten, copper or stainless steel, and the curvature radius of the needle tip is 10-200um.

In the miniaturized flat-panel device for rapidly measuring the particle size distribution of fine particles, a scanning electric field area is formed between the separation electrode and the sensitive electrode, the length of the scanning electric field area is 10-150 mm, and the width is 10-50 mm; The sensitive electrode is made of a porous metal plate, and the porous metal plate is made of a foamed metal material, wherein the resistivity of the foamed metal material is lower than 3.0×10 ^-8 Ω·m, including silver, copper, and gold. The pore density of the material is between 20 and 140.

In the miniaturized flat-panel device for quickly measuring the particle size distribution of fine particles, the separation electrodes adopt strip electrodes, and each separation electrode does not touch each other; the sensitive electrode adopts strip electrodes and has the same width as the corresponding separation electrodes. Sensitive electrodes are not in contact with each other.

In the miniaturized flat-panel device for rapidly measuring the particle size distribution of fine particles, each separation electrode is connected as a whole.

Described a kind of measuring method of the flat plate device of miniaturization rapid measurement fine particle size distribution, this method comprises the following steps:

a. The controller controls the sheath gas flow to enter the unipolar flat panel charging module at a certain flow rate through the vacuum pump and its drive circuit, and at the same time controls the sample gas flow to enter the flat panel detection module at a certain flow rate;

b. The sheath gas flow enters the unipolar charging area generated by the tip corona discharge of the discharge needle in the unipolar flat-plate charging module, and mixes with the unipolar charged ions diffused out of the discharge chamber through the conductive porous plate;

c. The sheath gas flow carrying charged ions enters the flat-panel detection module and mixes with the sample gas flow. Charge transfer occurs between the charged ions in the sheath gas flow and the fine particles in the sample gas flow, so that the fine particles in the sample gas flow are carried charge;

d. The mixed airflow enters the scanning electric field area formed between the separation electrode and the sensitive electrode, and the scanning voltage loaded on each separation electrode is controlled by the scanning voltage control circuit, so that the charged fine particles in the airflow generate electricity in the scanning electric field area. Migrate, and deflect to the corresponding sensitive electrode due to the difference in particle size, and then transmit it to the corresponding electrometer in the form of current;

e. The controller calls the calibration relationship between the particle size of the charged fine particles deflected to each sensitive electrode pre-stored in the memory and the scanning voltage loaded on each separation electrode, and obtains the deflection to each sensitive electrode under a certain scanning voltage. The particle size of the charged fine particles on the electrode;

f. The controller obtains the current value on each sensitive electrode detected by the electrometer through the micro-current detection processing circuit, calls the base current value on each sensitive electrode pre-stored in the memory, and subtracts the real current value on each sensitive electrode. To characterize the number concentration of charged fine particles under the corresponding particle size, and then draw the particle size distribution spectrum of the fine particles in the sample gas flow, and the particle size distribution spectrum of the fine particles is displayed on the display and stored in the memory.

In the measurement method of the flat panel device for the miniaturization and rapid measurement of the particle size distribution of fine particles, in step d, the scanning voltage loaded on each separation electrode is controlled by the scanning voltage control circuit, including the following situations:

d1. Control the scanning voltage applied on each separation electrode to be the same, so that the scanning electric field area forms a constant and uniform electric field area;

d2. Control the scanning voltage loaded on each separation electrode to be the same, change the range of the scanning electric field region by changing the number of separation electrodes, and then obtain uniform electric field regions of different ranges;

d3. Control the scanning voltage loaded on each separation electrode to gradually change from the sample gas inlet to the sample gas outlet, so that the scanning electric field area forms a stepped uniform electric field area.

In the measurement method of the flat panel device for rapidly measuring the particle size distribution of the miniaturized particles, in step e, the particle size of the charged fine particles deflected to each sensitive electrode is between the scanning voltage loaded on each separation electrode The calibration relationship of is obtained through the following steps:

e1. Introduce the filtered particle-free sample gas flow into the flat panel device, gradually increase the scanning voltage loaded on each separation electrode, and observe the change of the current value on each sensitive electrode detected by the electrometer through the display. When the current value is stable , recorded as the base current value on each sensitive electrode;

e2. Introduce the sample gas flow containing fine particles of a certain particle size generated by the standard particle generator into the flat panel device, adjust the scanning voltage loaded on each separation electrode, and observe the current on each sensitive electrode detected by the electrometer through the display If and only when the current value on the sensitive electrode closest to the sheath gas inlet channel is greater than the base current value, record the scanning voltage currently loaded on each separated electrode; then gradually reduce the voltage loaded on each separated electrode Scan the voltage, observe the current value change on each sensitive electrode detected by the electrometer through the display, and record the current load on each separation electrode if and only when the current value on the sensitive electrode next to the sheath gas inlet channel is greater than the base current value. The scanning voltage on the electrode; and so on, until the current value on all sensitive electrodes is the base current value, stop recording, and obtain the calibration relationship between the particle size and the scanning voltage loaded on each separation electrode;

e3. Sequentially control the standard particle generator to generate the sample gas flow containing fine particles of various particle sizes, repeat step e2, and obtain the particle size of the charged fine particles deflected to each sensitive electrode and the scanning voltage loaded on each separation electrode The calibration relationship between them.

The beneficial effects of the present invention are:

(1) The present invention adopts multi-electrometer parallel measurement, which is faster than single-electrometer measurement, and is suitable for rapid detection of particle size spectrum, such as rapid detection of particulate matter emissions from mobile pollution sources;

(2) Only sensitive electrodes are needed for detection in the present invention, and no external collection equipment such as Faraday cups are required, which makes the structure simple, easy to miniaturize and low cost;

(3) The structures of the unipolar plate charging module and the plate detection module of the present invention are both plate structures, which are easy to integrate and miniaturize;

(4) The number of separation electrodes on the second upper panel in the flat panel detection module of the present invention can be flexibly configured according to actual needs, which is easy to improve the resolution and speed of particle size detection, but at the same time does not increase the difficulty of the manufacturing process and the cost of the measurement system. size and cost;

(5) The entire production material of the present invention is high-temperature-resistant ceramics and metals, which can be applied to the detection of high-temperature particulate matter, so it can be applied to the detection of fixed high-temperature flue gas, and the miniaturized structure can also be applied to the detection of mobile source exhaust gas aspect;

(6) The present invention has high integration, small size, low cost, and integrated design is easy to carry around, and can realize mobile pollution source monitoring and multi-node networking monitoring in a large area and wide range.

Description of drawings

Fig. 1 is a schematic view of the device structure of the present invention;

Fig. 2 is the top view of the distribution of the discharge chamber of the unipolar flat charge module of the present invention;

Fig. 3 is the schematic diagram of the panel detection module of the present invention;

Fig. 4 is the top view of the distribution of the separation electrodes of the flat panel detection module of the present invention;

5 is a top view of the distribution of sensitive electrodes of the flat panel detection module of the present invention;

Fig. 6 is a partial schematic diagram of the scanning electric field of the present invention;

Fig. 7 is a flow chart of the method of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figures 1 to 6, a miniaturized flat-panel device for rapidly measuring the particle size distribution of fine particles includes a unipolar flat-panel charging module 1, a flat-panel detection module 2, and a microcurrent signal processing and voltage control module 3.

The unipolar flat-plate charging module 1 is used for charging the clean sheath gas, adopts a flat-plate structure, and includes a first upper panel 11 and a first lower panel 12 arranged parallel to each other and facing each other, and is evenly arranged on the first upper panel The six discharge needles 14 on 11 correspond vertically to the six discharge needles evenly arranged on the first lower panel 12, and the first upper panel 11 and the first lower panel 12 are respectively dug with discharge chambers 13 for placing the discharge needles 14 , the discharge chamber 13 on the first upper panel 11 and the first lower panel 12 are vertically corresponding, and the opening of the discharge chamber 13 is closed with a conductive porous plate 15 . A sheath gas intake passage 10 is formed between the first upper panel 11 and the first lower panel 12 .

The flat-panel detection module 2 is used to classify the fine particles in the sample gas flow, and adopts a flat-panel structure, including a second upper panel 21 and a second lower panel 22 arranged parallel to each other, and twelve of the second upper panel 21 Each separate electrode 23 is connected with twelve voltage sources 24 one by one through the perforated wire 29, and the twelve voltage sources 24 are centrally installed in the multi-port array voltage source 25, and the twelve sensitive electrodes 26 on the second lower panel 22 The twelve electrometers 27 are connected in one-to-one correspondence through perforated wires 29 . The second upper panel 21 is parallel to the first upper panel 11 and forms a sample gas inlet channel 20 .

The microcurrent signal processing and voltage control module 3 is a signal control and data acquisition processing part, including a controller 31, a unipolar high voltage source and its control circuit 32, a scanning voltage control circuit 33, a microcurrent detection processing circuit 34, a vacuum pump and its drive circuit 35 , memory 36 and display 37 .

The input end of the unipolar high voltage source and its control circuit 32 is connected to the output end of the controller 31 , and the output end of the unipolar high voltage source and its control circuit 32 is connected to the discharge needle 14 . The input terminal of the scanning voltage control circuit 33 is connected to the output terminal of the controller 31 , and the output terminal of the scanning voltage control circuit 33 is connected to the input terminal of the multi-port array voltage source 25 . The output end of the microcurrent detection processing circuit 34 is connected to the input end of the controller 31 , and the input end of the microcurrent detection processing circuit 34 is connected to the output end of the electrometer 27 . The input end of the vacuum pump and its drive circuit 35 is connected to the output end of the controller 31, and the vacuum pump and its drive circuit 35 are connected to the waste gas outlet 28 and the sheath gas inlet channel 10 and the second upper panel 21 and the second lower panel 22. The inlet of the sample gas inlet channel 20 is connected. The memory 36 is interactively connected with the controller 31 . The input of the display 37 is connected to the output of the controller 31 .

The first upper panel 11 , the first lower panel 12 , the second upper panel 21 and the second lower panel 22 are all made of alumina ceramics. The distance between the first upper panel 11 and the first lower panel 12 is 2 to 6 mm, and the distance between the second upper panel 21 and the second lower panel 22 is 1 to 8 mm, so as to ensure that the air inlet slit of the sample gas inlet channel 20 is 0.5 ~ 2mm.

The twelve discharge needles 14 are vertically symmetrical in an array, made of tungsten, copper or stainless steel, and the radius of curvature of the needle tip is 10-200um.

A scanning electric field area is formed between the separation electrode 23 and the sensitive electrode 26, the length of the scanning electric field area is 10-150 mm, and the width is 10-50 mm. The sensitive electrode 26 is made of a porous metal plate, and the porous metal plate is made of a foamed metal material, wherein the resistivity of the foamed metal material is lower than 3.0×10 ^-8 Ω·m, including silver, red copper, and gold, and the pore density of the foamed metal material is between Between 20 and 140.

Using the thick-film ceramic printing technology, the separated electrodes 23 that are evenly distributed and have the same structure are printed on the second upper panel 21 , and the sensitive electrodes 26 vertically corresponding to the separated electrodes 23 are printed on the second lower panel 22 . Both the separation electrodes 23 and the sensitive electrodes 26 are strip-shaped electrodes, and the widths of the separation electrodes 23 and the sensitive electrodes 26 corresponding to each other are the same. A configuration of the separated electrodes 23 is as follows: each separated electrode 23 is insulated from each other and does not touch each other, and is respectively connected to the voltage source 24 in the multi-port array voltage source 25 through a perforated wire 29 in a one-to-one correspondence. The separated electrodes 23 provide a scanning voltage, and a uniform electric field is formed between the separated electrodes 23 connected to the voltage and the corresponding sensitive electrodes 26 on the second lower panel 22. When the number of separated electrodes 23 connected to the voltage increases, the region of the uniform electric field will In the same way, when the number of the separated electrodes 23 of the connected voltage decreases, the area of the uniform electric field will become smaller; the structure of the separated electrodes 23 of the tablet device described in the present invention cooperates with the multi-port array voltage source 25 to realize practical application The requirements for the range of adjustable and uniform electric field.

The above-mentioned multi-port array voltage source 25 is independently connected to each separate electrode 23 and does not affect each other. By controlling the scanning voltage supplied to each separate electrode 23, the scanning electric field area formed between the separate electrode 23 and the sensitive electrode 26 is controlled. The magnitude of the electric field strength. This structure of independently providing scanning voltage can control the same voltage between the separate electrodes 23 to form a uniform electric field in the flat panel detection module 2; Through the variable voltage, a variable electric field is formed in the flat panel detection module 2, which realizes the requirement of an adjustable electric field intensity range in practical applications.

The positions of each sensitive electrode 26 on the second lower panel 22 are different, and the sensitive electrodes 26 at different positions represent charged fine particles of different particle sizes, and the current value obtained on each sensitive electrode 26 represents the number of fine particles of corresponding particle sizes Concentration; the structure of the sensitive electrode 26 of the flat panel device described in the present invention realizes the requirement of quickly obtaining the particle size distribution of fine particles in practical applications.

Another configuration form of the separated electrodes 23 is: the separated electrodes 23 are connected as a whole and printed at one time by thick-film ceramic printing technology. When the separated electrodes 23 adopt a connected electrode structure, the scanning voltage applied to each separated electrode 23 is consistent during measurement.

As shown in Figure 7, a kind of measuring method of the plate device of miniaturization fast measurement fine particle size distribution, comprises the following steps:

S1. The controller 31 controls the flow of the sheath gas to enter the unipolar flat panel charging module 1 at a certain steady flow rate through the vacuum pump and its driving circuit 35, and simultaneously controls the flow of the sample gas to enter the flat panel detection module 2 at a certain steady flow velocity.

S2. The sheath gas flow enters the unipolar charging area generated by the tip corona discharge of the discharge needle 14 in the unipolar flat-plate charging module 1, and the unipolar charging area diffuses out of the discharge chamber 13 through the conductive porous plate 15. Mixing of charged ions;

The discharge needle 14 is in an array vertically symmetrical structure, the unipolar high-voltage source and its control circuit 32 provide high voltage to the discharge needle 14, and the discharge at the tip of the discharge needle 14 in the discharge chamber 13 generates a unipolar charged area, and the corona discharge generates The unipolar charged ions diffuse out of the discharge chamber 13 through the conductive porous plate 15 closing the discharge chamber 13 and gently enter the sheath gas inlet channel 10 to mix with the sheath gas flow.

S3. The sheath gas flow carrying charged ions enters the flat-panel detection module 2 and mixes with the sample gas flow. Charge transfer occurs between the charged ions in the sheath gas flow and the fine particles in the sample gas flow, so that the fine particles in the sample gas flow are charged. charge.

S4, the mixed airflow enters the scanning electric field area formed between the separation electrode 23 and the sensitive electrode 26 in a laminar flow state, and the scanning voltage loaded on each separation electrode 23 is controlled by the scanning voltage control circuit 33, so that the airflow in the airflow The charged fine particles undergo electromigration in the scanning electric field area, and are deflected to the corresponding sensitive electrode 26 due to the difference in particle size, and then transmitted to the corresponding electrometer 27 in the form of current.

S5. The controller 31 obtains the calibration relationship between the particle size of the charged fine particles deflected onto each sensitive electrode 26 prestored in the memory 36 and the scanning voltage loaded on each separating electrode 23 to obtain a certain scanning voltage. The particle size of the charged fine particles deflected onto each sensitive electrode 26 .

S6, the controller 31 obtains the current value on each sensitive electrode 26 detected by the electrometer 27 through the micro-current detection processing circuit 34, calls the base current value on each sensitive electrode 26 prestored in the memory 36, and subtracts each sensitive electrode 26 The actual current value above is used to characterize the number concentration of charged fine particles under the corresponding particle size, and then draw the particle size distribution spectrum of the fine particles in the sample gas flow, which is displayed on the display 37 and stored in the memory 36. The final waste gas is taken out and filtered by the vacuum pump and its driving circuit 35, and then recycled.

In the above step S4, the scanning voltage applied to each separation electrode 23 is controlled by the scanning voltage control circuit 33, including the following situations:

(1) The scanning voltage applied to each separation electrode 23 is controlled to be the same, and a constant and uniform electric field region is formed in the flat panel detection module 2 .

(2) Control the scanning voltage loaded on each separation electrode 23 to be the same. By changing the number of separation electrodes 23, different ranges of constant and uniform electric field regions are formed in the flat panel detection module 2, and charged fine particles of different particle sizes enter a uniform intensity. The electric field area is finally detected to provide protection. Charged fine particles may be too lightly charged to be detected during deflection. By changing the electric field range of the flat-panel detection module 2, the detection efficiency of charged fine particles is improved as a whole, and the measurement range of the particle size of the fine particles is widened.

(3) Control the scanning voltage loaded on each separation electrode 23 to gradually change from the sample gas inlet to the sample gas outlet in sequence, and a stepped uniform electric field area is formed in the flat panel detection module 2 . After the charged fine particles enter the stepped uniform electric field region, the first form is: the voltage of the separation electrode 23 increases gradually from the sample gas inlet to the sample gas outlet, and the charged fine particles are in the deflection process, along with the electric field strength of the uniform electric field region The deflection speed of the charged fine particles is also faster and faster, which reduces the deflection time of the charged fine particles as a whole and shortens the entire measurement time; the second form is: the voltage of the separation electrode 23 is sequentially from the sample gas inlet The gas outlet decreases gradually, and fine particles of different particle sizes enter from one uniform electric field area to another uniform electric field area. After multiple separations in the uniform electric field area, the resolution of fine particle particle size measurement is improved as a whole.

In the above step S5, the calibration relationship between the particle diameter of the charged fine particles deflected to each sensitive electrode 26 and the scanning voltage loaded on each separation electrode 23 is mainly obtained by the following process: the sample produced by the standard particle generator The gas flow is introduced into the tablet device described in the present invention, and the particle diameter represented by the sensitive electrode 26 at each position on the second lower panel 22 is calibrated by controlling the voltage connected between the multi-port array voltage source 25 and each separation electrode 23, specifically Obtained by the following steps:

S51, first introduce the filtered particle-free sample gas flow into the flat panel device described in the present invention, gradually increase the voltage connected between the multi-port array voltage source 25 and each separation electrode 23, and observe each position on the second lower panel 22 The current signal on the sensitive electrode 26 is recorded as the background current value of the device under the particle-free state, and the background current value is used as the base current value on each sensitive electrode 26.

S52, then the sample gas flow containing fine particles of a certain particle size produced by the standard particle generator is introduced into the flat panel device described in the present invention, and the voltage connected between the multi-port array voltage source 25 and each separation electrode 23 is adjusted, by observing , if and only when the current value on the sensitive electrode 26 closest to the sheath gas inlet channel (10) is greater than the base current value, record the scanning voltage currently applied to each separation electrode 23; then gradually reduce the load on each separation electrode 23 The scanning voltage on the electrodes 23, by observing, if and only when the current value on the sensitive electrode 26 that is 10 times closer to the sheath gas inlet channel is greater than the base current value, record the scanning voltage currently loaded on each separate electrode 23; By analogy, stop recording until all sensitive electrodes 26 can only detect the background current value, save the entire test record in the memory 36, and obtain the calibration relationship between the particle size and the scanning voltage loaded on each separation electrode 23 .

S53, sequentially control the standard particle generator to generate the sample gas flow containing fine particles of various particle sizes, repeat step S52, obtain the particle size of the charged fine particles deflected to each sensitive electrode 26 and the scanning data loaded on each separation electrode 23 The calibration relationship between the voltages.

The above-mentioned embodiments are only descriptions of the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, those skilled in the art may make various modifications to the technical solutions of the present invention. and improvements, all should fall within the scope of protection determined by the claims of the present invention.

Claims (9)

1. The utility model provides a miniaturized dull and stereotyped device of rapid survey fine particle size distribution which characterized in that: the device comprises a unipolar flat plate charge module (1), a flat plate detection module (2) and a micro-current signal processing and voltage control module (3);

the unipolar flat plate charging module (1) comprises a first upper panel (11) and a first lower panel (12) which are parallel to each other and are arranged oppositely, discharge chambers (13) which are uniformly arranged on the first upper panel (11) and the first lower panel (12) and vertically correspond to each other, discharge needles (14) arranged in the discharge chambers (13), and conductive porous plates (15) for sealing the discharge chambers (13); a sheath gas inlet channel (10) is formed between the first upper panel (11) and the first lower panel (12);

the flat plate detection module (2) comprises a second upper panel (21) and a second lower panel (22) which are parallel to each other and are arranged oppositely, a plurality of separation electrodes (23) arranged on the second upper panel (21), a plurality of voltage sources (24) which are connected with the separation electrodes (23) in a one-to-one corresponding mode, a multi-port array voltage source (25) for installing the voltage sources (24) in a centralized mode, sensitive electrodes (26) which are arranged on the second lower panel (22) and are in one-to-one corresponding mode with the separation electrodes (23), a plurality of electrometers (27) which are connected with the sensitive electrodes (26) in a one-to-one corresponding mode and an exhaust gas outlet (28) which is arranged at the rear ends of the second upper panel (21) and the second lower panel (22); the second upper panel (21) and the first upper panel (11) are parallel to each other and form a sample gas inlet channel (20);

the micro-current signal processing and voltage control module (3) comprises a controller (31), a unipolar high-voltage source and a control circuit (32) thereof which are connected with the discharge needle (14), a scanning voltage control circuit (33) which is connected with the multi-port array voltage source (25), a micro-current detection processing circuit (34) which is connected with the electrometer (27), a vacuum pump and a driving circuit (35) thereof which are connected with the sheath gas inlet channel (10), the sample gas inlet channel (20) and the waste gas outlet (28), a memory (36) which is interactively connected with the controller (31) and a display (37) of which the input end is connected with the output end of the controller (31); the output end of the micro-current detection processing circuit (34) is connected with the input end of a controller (31), and the output end of the controller (31) is respectively connected with the input end of a unipolar high-voltage source and a control circuit (32) thereof, the input end of a scanning voltage control circuit (33) and the input end of a vacuum pump and a driving circuit (35) thereof.

2. The miniaturized flat plate device for rapidly measuring the particle size distribution of fine particles according to claim 1, wherein: the first upper panel (11), the first lower panel (12), the second upper panel (21) and the second lower panel (22) are all made of alumina ceramics; the distance between the first upper panel (11) and the first lower panel (12) is 2-6 mm, the distance between the second upper panel (21) and the second lower panel (22) is 1-8 mm, and the air inlet seam of the sample air inlet channel (20) is 0.5-2 mm.

3. The miniaturized flat plate device for rapidly measuring the particle size distribution of fine particles according to claim 1, wherein: the discharge needles (14) are in an array vertical symmetrical structure and are made of tungsten, copper or stainless steel, and the curvature radius of the needle points is 10-200 um.

4. The miniaturized flat plate device for rapidly measuring the particle size distribution of fine particles according to claim 1, wherein: a scanning electric field area is formed between the separation electrode (23) and the sensitive electrode (26), the length of the scanning electric field area is 10-150 mm, and the width of the scanning electric field area is 10-50 mm; the sensitive electrode (26) is prepared by adopting a porous metal plate which is prepared by adopting a foam metal material, wherein the resistivity of the foam metal material is lower than 3.0 x 10 ^-8 Omega-m, comprising silver, red copper and gold, and the pore density of the foam metal material is between 20 and 140.

5. The miniaturized flat plate device for rapidly measuring the particle size distribution of fine particles according to claim 1, wherein: the separation electrodes (23) are strip-shaped electrodes, and the separation electrodes (23) are not in contact with each other; the sensitive electrodes (26) are strip-shaped electrodes and have the same width with the corresponding separation electrodes (23), and the sensitive electrodes (26) are not in contact with each other.

6. The miniaturized flat plate device for rapidly measuring the particle size distribution of fine particles according to claim 1, wherein: the separation electrodes (23) are connected into a whole.

7. The method for measuring a miniaturized flat plate device for rapidly measuring the particle size distribution of fine particles according to claim 1, which comprises the steps of:

a. the controller (31) controls the sheath gas flow to enter the unipolar flat plate charge module (1) at a certain flow rate through the vacuum pump and the driving circuit (35) thereof, and controls the sample gas flow to enter the flat plate detection module (2) at a certain flow rate;

b. the sheath gas flow enters a unipolar charge area generated by corona discharge of the tip of a discharge needle (14) in the unipolar flat plate charge module (1) and is mixed with unipolar charged ions diffused out of a discharge chamber (13) through a conductive porous plate (15);

c. the sheath gas airflow loaded with the charged ions enters the flat plate detection module (2) to be mixed with the sample gas airflow, and the charged ions in the sheath gas airflow and the fine particles in the sample gas airflow are subjected to charge transfer to charge the fine particles in the sample gas airflow;

d. the mixed airflow enters a scanning electric field area formed between the separation electrodes (23) and the sensitive electrodes (26), and scanning voltages loaded on the separation electrodes (23) are controlled by a scanning voltage control circuit (33), so that charged fine particles in the airflow are subjected to electro-migration in the scanning electric field area, are deflected to the corresponding sensitive electrodes (26) due to different particle sizes, and are transmitted to the corresponding electrometers (27) in a current mode;

e. the controller (31) obtains the particle size of the charged fine particles deflected to each sensitive electrode (26) under a certain scanning voltage by calling the calibration relation between the particle size of the charged fine particles deflected to each sensitive electrode (26) and the scanning voltage loaded on each separation electrode (23) which are prestored in the memory (36);

f. the controller (31) acquires current values of all the sensitive electrodes (26) detected by the electrometer (27) through the micro-current detection processing circuit (34), calls base current values of all the sensitive electrodes (26) prestored in the memory (36), and subtracts the base current values to obtain real current values of all the sensitive electrodes (26) so as to represent the number concentration of charged fine particles under corresponding particle sizes, and further draws a fine particle size distribution map in the sample gas flow, wherein the fine particle size distribution map is displayed on the display (37) and stored in the memory (36).

8. The method for miniaturized and rapid measurement of fine particle size distribution of flat panel apparatus according to claim 7, wherein in step d, the control of the scanning voltage applied to each of the separated electrodes (23) by the scanning voltage control circuit (33) comprises the following conditions:

d1, controlling the same scanning voltage loaded on each separation electrode (23) to enable the scanning electric field area to form a constant uniform electric field area;

d2, controlling the same scanning voltage loaded on each separation electrode (23), and changing the range of the scanning electric field area by changing the number of the separation electrodes (23) so as to obtain uniform electric field areas in different ranges;

and d3, controlling the scanning voltage loaded on each separation electrode (23) to sequentially change from sample gas inlet to sample gas outlet, so that the scanning electric field area forms a step uniform electric field area.

9. The method for miniaturized and fast measurement of fine particle size distribution of flat panel device according to claim 7, wherein in step e, the calibration relationship between the particle size of the charged fine particles deflected to each sensitive electrode (26) and the scanning voltage loaded on each separate electrode (23) is obtained by:

e1, introducing the filtered sample gas flow without charged particles into the flat plate device, gradually increasing the scanning voltage loaded on each separation electrode (23), observing the current value change on each sensitive electrode (26) detected by the electrometer (27) through a display (37), and recording the current value as the substrate current value on each sensitive electrode (26) when the current value is stable;

e2, introducing a sample gas flow containing fine particles with certain particle size generated by a standard particle generator into the flat panel device, debugging the scanning voltage loaded on each separation electrode (23), observing the current value change of each sensitive electrode (26) detected by an electrometer (27) through a display (37), and recording the scanning voltage currently loaded on each separation electrode (23) when and only when the current value of the sensitive electrode (26) closest to the sheath gas inlet channel (10) is larger than the base current value; then gradually reducing the scanning voltage loaded on each separation electrode (23), observing the current value change of each sensitive electrode (26) detected by the electrometer (27) through a display (37), and recording the scanning voltage currently loaded on each separation electrode (23) if and only if the current value of the sensitive electrode (26) next to the sheath gas inlet channel (10) is larger than the substrate current value; analogizing in turn, stopping recording until the current values on all the sensitive electrodes (26) are the substrate current values, and obtaining the calibration relation between the grain diameter and the scanning voltage loaded on each separation electrode (23);

e3, sequentially controlling the standard particle generator to generate sample gas flow containing fine particles with various particle sizes, and repeating the step e2 to obtain the calibration relation between the particle sizes of the charged fine particles deflected to the sensitive electrodes (26) and the scanning voltage loaded on the separation electrodes (23).

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