JP3786049B2 - Airborne particulate matter collection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for collecting suspended particulate matter in the atmosphere .
[0002]
Of the dust suspended in the atmosphere, those having a particle size of 10 μm or less are called suspended particulate matter (SPM). This suspended particulate matter includes rolled-up soil, etc., but black smoke, unburned fuel, sulfur compounds, etc., emitted by diesel cars account for a lot (35% is from diesel cars in Kanto). Is said to be more harmful. Particulate matter caused by exhaust gas from this diesel vehicle is particularly referred to as DEP. In addition, those having a smaller particle diameter of 2.5 μm or less are referred to as microparticulate substances (PM2.5), and research and research are actively conducted in the West. In the case of this PM2.5, it is said that the ratio of exhaust gas from diesel vehicles becomes higher.
[0003]
As a method for collecting such suspended particulate matter, conventionally, a method is adopted in which the suspended particulate matter is adhered to the filter by sucking the air and passing it through the filter.
[0004]
[Problems to be solved by the invention]
[0005]
By the way, it is practically impossible to take out individual particles from the filter by the conventional collection method in which the suspended particulate matter adheres to the filter by sucking the air and passing through the filter as described above . However, there is a problem that it is difficult to use the collected particulate matter for various measurements and analyses.
[0006]
In addition, when the collected suspended particulate matter is used, for example, for measuring the particle size distribution of the suspended particulate matter using a laser diffraction / scattering type particle size distribution measuring device, the sample concentration is in a concentration range suitable for measurement. there is also need to measure the diffracted and scattered light is irradiated bets on the laser beam to it, in order to provide the suspended particulate matter on the basis of the concentration range suitable for such measurements in various measurements, for example, a constant It is conceivable to collect a certain amount of suspended particulate matter by aspirating the atmosphere for a period of time to collect suspended particulate matter, but the concentration of suspended particulate matter in the atmosphere is not constant, and Since the concentration also varies, there is a problem that the amount of particles collected at the time when the collection is finished is not expected and a sample having a required concentration range cannot be obtained.
[0007]
The present invention has been made to solve the above problems point, easily subjected collecting suspended particulate matter in the various measurements, and, reliably floating particles based on the particular concentration range scavenged An object of the present invention is to provide a collection device that can do this.
[0008]
To achieve the above object, collecting device suspended particulate matter of the present invention comprises a collecting container, a pump for sucking air into the collecting container, disposed collecting vessel, monopolar ion Discharge electrode that charges the suspended particulate matter in the container and a transparent member that attracts and collects the suspended particulate matter charged in the collection container by applying a potential difference to the discharge electrode A dust collecting electrode comprising: a light irradiating means for irradiating the dust collecting electrode with light; a detecting means for detecting the transmitted light intensity of the light collecting electrode; and a detected value on the dust collecting electrode. Memorize the relationship with the amount of suspended particulate matter, set the amount of suspended particulate matter arbitrarily, and reach the value corresponding to the amount collected by the detection means and a control means for stopping the pump when the It is characterized by a.
[0009]
Here, in the present invention, the dust collecting electrode made of a transparent member includes, for example, a structure in which the surface of a transparent plate such as a glass plate or a resin plate is coated with a transparent electrode, or a glass plate coated with a transparent electrode or the like. It includes a structure in which a transparent liquid such as water is accommodated in a dish-like or container-like shape and suspended particulate matter is collected in the liquid.
[0010]
The present invention sucks the atmosphere in the collecting container, as well as scavenged on the dust collecting electrode the suspended particulate matter in the vessel is charged by the discharge electrodes, the electrodes comprising the dust collecting electrode of a transparent member and by the concentration information from the intensity of the transmitted light wherein the collector suspended particulate matter that is scavenged on the dust electrodes of the dust-collecting electrodes, that is it possible to obtain a collecting volume information, the desired object That is what we are trying to achieve.
[0011]
That is , when monopolar ions are generated from the discharge electrode while the atmosphere is sucked into the collection container, the suspended particulate matter contained in the atmosphere sucked into the collection container is charged, and a potential difference is generated with respect to the discharge electrode. Is attracted to the dust collecting electrode side and is collected on the dust collecting electrode sequentially, and is uniformly deposited on the surface of the dust collecting electrode. If light is applied to the dust collecting electrode made of a transparent member and the intensity of the transmitted light is detected, the detected value becomes a value corresponding to the amount of suspended particulate matter collected on the dust collecting electrode. In other words, the detected value of the transmitted light intensity of the dust collection electrode is information that indicates the amount of suspended particulate matter collected on the dust collection electrode in real time, and the transmitted light intensity and suspended particulate matter are obtained by calibration. The relationship with the amount of collected water can be obtained, and the relationship is stored in the control means for controlling the pump. In addition, for this control means, it is possible to arbitrarily set the collection amount of the suspended particulate matter, and when the detection value of the transmitted light by the detection means reaches a value corresponding to the set collection amount. By configuring the pump to automatically stop, it is possible to collect a set amount of suspended particulate matter on the collecting electrode.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram representing a mechanical configuration and a block diagram representing an electrical configuration.
[0013]
The collection container 1 is formed with an air inlet 1 a and a communication port 1 b to the suction port of a pump (collecting compressor) 2. By driving the pump 2, the inlet 1 a is passed through the inlet 1 a. The air is sucked into the collection container 12. In the collection container 1, a discharge electrode 3 is disposed at the top, and a dust collection electrode 4 is disposed in the vicinity of the bottom. The collection container 1 has a lid or an opening / closing door (not shown) for taking in and out the dust collecting electrode 4. When the lid or the opening / closing door is closed, the inflow port 1 a and the communication port are provided. Only 1b is in communication with the outside.
[0014]
A high voltage from the high-voltage power supply 5 is applied to the discharge electrode 3, whereby the air in the vicinity of the discharge electrode 3 is ionized and unipolar ions are generated.
The dust collecting electrode 4 is a transparent flat electrode having a smooth surface, and has a structure in which, for example, a glass plate or a resin surface is coated with a transparent electrode. The dust collecting electrode 4 is connected to a ground potential 6. Has been.
[0015]
In the above configuration, by applying a high voltage to the discharge electrode 3 while driving the pump 2, unipolar ions generated by the ionization of air in the vicinity of the discharge electrode 3 are collected by the potential difference with the dust collection electrode 4. It moves to the electrode 4 side and in contact with the suspended particulate matter P contained in the atmosphere in the collection container 1 in the process, it is charged. Then, the charged suspended particulate matter P moves toward the dust collecting electrode 4 due to the potential difference between the discharge electrode 3 and the dust collecting electrode 4 and is collected on the surface of the dust collecting electrode 4.
[0016]
A transparent window 1c made of a glass plate or the like is provided on the bottom surface of the collection container 1 at a position just below the central portion of the dust collection electrode 4, and a ceiling directly above the window 1c. A similar transparent window 1d is also provided on the surface. A light source 7 for irradiating a parallel beam made of laser light or lamp light vertically upward is disposed below the window 1c, while a collection of parallel beams from the light source 7 is disposed above the window 1d. A photodetector 8 that detects the intensity of light transmitted through the dust electrode 4 is disposed.
[0017]
The detection output of the photodetector 8 is taken into the arithmetic / control device 9. In the calculation / control device 8, the output of the photodetector 8 in a state in which no suspended particulate matter P is collected on the surface of the dust collecting electrode 4, and a known amount of suspended particulate matter P is collected in the dust collecting electrode. Between the detected value of the transmitted light intensity by the photodetector 8 and the amount of the suspended particulate matter P obtained by calibration using the output of the photodetector 8 collected on the surface of 4 Is stored in advance.
[0018]
The arithmetic / control device 9 supplies drive control signals to the pump 2 and the high-voltage power supply 4. Further, the calculation / control device 9 can print out the concentration information of the suspended particulate matter P on the dust collecting electrode 4 based on the output of the photodetector 8 by connecting the printer 10. Yes.
[0019]
The above-described embodiment of the present invention can be used as either a concentration measuring device for suspended particulate matter P in the atmosphere or a collecting device for suspended particulate matter P in the atmosphere.
[0020]
When used as a concentration measuring device, suspended particulate matter on the dust collection electrode 4 based on the output of the photodetector 8 at regular intervals, for example, in a state where a high voltage is applied to the discharge electrode 3 while driving the pump 2. The collected amount information of P is output to the printer 10. By keeping the amount of air sucked per unit time by the pump 2 constant, the total amount of air sucked into the collection container 1 up to that point in time after the start of starting can be determined. The collected amount information of the suspended particulate matter P sequentially output to the printer 10 represents the amount of the suspended particulate matter P contained in the total amount of air sucked into the collection container 1 at each time point. Moreover, if the difference of the collection amount information for every fixed time passage is calculated, the change with time of the concentration of the suspended particulate matter P in the atmosphere is represented.
[0021]
On the other hand, when the embodiment of the present invention is used as a collection device for the suspended particulate matter P, a desired particle concentration (collection amount) is set in the calculation / control device 9 to start the device. The arithmetic / control device 9 automatically stops the pump 2 and the discharge electrode 3 when the collected amount information based on the output of the photodetector 8 matches the set value. As a result, a set amount of suspended particulate matter P is collected on the dust collecting electrode 4.
[0022]
The suspended particulate matter P collected in this way is kept attached to the surface of the transparent flat-plate-shaped dust collecting electrode 4, for example, by using a laser diffraction / scattering type particle size distribution measuring device. The distribution can be measured over a wide particle size range with high resolution. In other words, a laser diffraction / scattering particle size distribution measuring device measures the spatial intensity distribution of diffraction / scattered light obtained by irradiating a group of particles to be measured in a dispersed state with laser light, and uses Mie scattering theory or Fraunhofer diffraction It is converted into particle size distribution using theory, and the concentration of the particles to be measured can be obtained over a wide particle size range as long as sufficient diffracted / scattered light intensity is obtained and multiple scattering is not caused. A high-resolution particle size distribution can be obtained.
[0023]
In addition, since the suspended particulate matter P collected by the above embodiment is attached to the surface of the transparent flat dust collecting electrode 4, the conventional filter can be used even when observing with a microscope. The particle image is not affected by the background image as in the collection method according to, and there is an advantage that a clear image can be observed.
[0024]
In the above embodiment, the example in which the suspended particulate matter P is attached to the surface using a transparent flat plate as the dust collecting electrode 4 is shown. As shown in FIG. A petri dish-shaped collecting tool 4a, which is made of a transparent material coated with a transparent electrode and provided with conductivity, is mounted on the upper surface of an equivalent transparent flat-plate-shaped dust collecting electrode 4. A liquid is placed in the collecting tool 4a. L may be accommodated so that the charged suspended particulate matter P is collected in the liquid L. Even in this case, by performing the calibration in a state including the liquid L, the output of the photodetector 8 represents the collected amount information of the suspended particulate matter P as described above.
[0025]
Further, when the suspended particulate matter P is collected in the liquid L in this way, when measuring the particle size distribution with a laser diffraction / scattering type particle size distribution measuring device, the particles to be measured are dispersed in the liquid medium. What is necessary is just to perform what is called wet measurement which irradiates a laser beam, and it is convenient if the liquid L is the same liquid as the liquid medium used for the wet measurement.
[0026]
【The invention's effect】
As described above, according to the present invention, the suspended particulate matter contained in the atmosphere sucked into the collection container is charged by the discharge electrode, and the charged particles are formed by the transparent member and irradiated with light. The amount of the suspended particulate matter collected on the dust collecting electrode is obtained by detecting the intensity of the light transmitted through the dust collecting electrode and collecting it. When the amount reaches the preset amount, the air suction is automatically stopped and the collection is completed, so even if the concentration of suspended particulate matter in the air changes due to the supplemental concentration, it is always positive. Accurately set amount of suspended particulate matter can be collected. For example, when it is used for measurement of particle size distribution by laser diffraction / scattering type particle size distribution measuring device, etc. It is possible to prepare a sample to be measured.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration.
FIG. 2 is an explanatory diagram of a configuration example of a dust collection electrode according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Collection container 2 Pump 3 Discharge electrode 4 Dust collection electrode 5 High voltage power supply 6 Ground potential 7 Light source 8 Light detector 9 Calculation / control apparatus 10 Printer P Suspended particulate matter

Claims (1)

A device that collects suspended particulate matter in the atmosphere,
A collection container, a pump that sucks air into the collection container, a discharge electrode that is disposed in the collection container and generates unipolar ions to charge suspended particulate matter in the container, and the discharge A dust collecting electrode made of a transparent member that attracts and collects suspended particulate matter charged in the collecting container by applying a potential difference to the electrode, and a light irradiation means for irradiating the dust collecting electrode with light And a detecting means for detecting the intensity of the transmitted light through the dust collecting electrode, the relationship between the detected value and the amount of the suspended particulate matter on the dust collecting electrode, and the collection of the suspended particulate matter In the atmosphere, it is possible to arbitrarily set the amount, and provided with control means for stopping the pump when the detection value by the detection means reaches a value corresponding to the set collection amount Airborne particulate matter collector .

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