JP4058624B2 - Device for collecting and measuring suspended particulate matter in the atmosphere - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for collecting and measuring suspended particulate matter present in the atmosphere.
[0002]
[Prior art]
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 most of them are graphite, unburned fuel, and sulfur compounds emitted by diesel vehicles (35% in the Kanto region are from diesel vehicles). 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 called 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]
Investigate the shape of suspended particulate matter (SPM) and microparticulate matter (PM2.5) in the atmosphere as described above, measure the particle size distribution, or identify the chemical substances contained therein To do so, it is necessary to collect these particulate matter from the atmosphere.
[0004]
Such a method for collecting suspended particulate matter in the atmosphere is most commonly a method for collecting suspended particulate matter on a filter (see, for example, Patent Document 1). However, it is extremely difficult to extract the particulate matter adhering to the filter alone. Therefore, when observing with a microscope, the particulate matter attached to the filter is observed. In this filter image, the particle image becomes unclear and difficult to observe. In addition, even when the collected suspended particulate matter is subjected to various chemical analyses, it is difficult to extract the suspended particulate matter alone from the filter. In this case, for example, in an X-ray fluorescence spectrometer, it is difficult to irradiate only the particles with X-rays, and there is a problem that the analysis becomes substantially impossible.
[0005]
In view of this, the present inventor, in cooperation with others, sucks the atmosphere into a collection container in which the discharge electrode and the dust collection electrode are housed, and removes the suspended particulate matter sucked into the container from the discharge electrode. There has already been proposed a method of charging with polar ions and attracting and collecting the charged suspended particulate matter to a dust collecting electrode to which a potential difference is given to the discharge electrode (for example, Japanese Patent Application Nos. 2001-216198 and 2001). Japanese Patent Application No. 2002-12322).
[0006]
The suspended particulate matter electrically collected on such a dust collection electrode can be easily extracted as a single substance, easily observed under a microscope, and easily sampled into various chemical analysis instruments. It becomes. Furthermore, there is an advantage that the particle size distribution can be easily measured by a laser diffraction / scattering type particle size distribution measuring apparatus.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-50870 (Page 5-8, FIGS. 1-3)
[0008]
[Problems to be solved by the invention]
By the way, according to the above proposal by the present inventors, when an appropriate amount of suspended particulate matter is collected in one dust collecting electrode, the dust collecting electrode is taken out and used for various measurements. When observing suspended particulate matter over time, it is necessary to take out the previous dust collection electrode and place a new dust collection electrode before use in the container. This is a tedious task for continuous observation of substances.
[0009]
The present invention has been made in view of such circumstances, and continuously collects suspended particulate matter in the atmosphere under great labor-saving or unmanned conditions, and sequentially measures the particle size distribution. It is an object of the present invention to provide can Ru equipment of things.
[0010]
[Means for Solving the Problems]
Collecting and measuring system of suspended particulate matter in the air of the present invention is an apparatus for measuring and collecting suspended particulate matter in the atmosphere, and collection vessel, in the collection vessel A pump that sucks air, a discharge electrode that is placed in a collection container and generates monopolar ions to charge suspended particulate matter in the container, and a trap is obtained by applying a potential difference to the discharge electrode. A collecting device comprising a dust collecting electrode that attracts and collects suspended particulate matter charged in the collecting container, and suspended particles that are arranged adjacent to the collecting device and collected by the collecting device A dust collecting electrode of the collecting device is a transparent and flexible film-like member provided with a conductive coating, and penetrates the collecting container. Arranged movably from the outside, the measuring device has its collection The dust collection electrode drawn out of the collection container is irradiated with laser light using the sample holding member as a sample holding member, and the spatial intensity distribution of diffracted / scattered light due to suspended particulate matter adhering to it is measured and its floating It is characterized by being a laser diffraction / scattering type particle size distribution measuring device for calculating the particle size distribution of particulate matter.
[0011]
Drawer Here, in the absorption-measuring device for suspended particulate matter in the air of the present invention, by winding the fill beam-shaped dust collecting electrodes, a portion was collected suspended particulate matter out of the container In addition, it is possible to suitably employ a configuration (claim 2) including a winding mechanism that draws an uncollected portion into the container.
[0012]
The present invention basically employs a structure in which suspended particulate matter is charged by a discharge electrode arranged in a collection vessel and electrically attracted to a dust collection electrode, as in the previous proposal, The dust collecting electrode is transparent and flexible, and the film dust collecting electrode is disposed so as to be movable from the outside through the collection container to collect suspended particulate matter. By irradiating a transparent film-like dust collecting electrode moved outside the collection container with laser light for measurement by a laser diffraction / scattering particle size distribution measuring device, the intended purpose is achieved. is there.
[0013]
That is, in the collection / measurement apparatus of the present invention, when the atmosphere is sucked into the collection container by a pump and the unipolar ions are generated by the discharge electrode arranged in the collection container, the unipolar ions Moves toward the dust collection electrode, which has a potential difference with respect to the discharge electrode, and in the process, contacts the suspended particulate matter contained in the air sucked into the collection container and charges it. . The charged suspended particulate matter moves to a dust collecting electrode that is similarly given a potential difference with respect to the discharge electrode, and is collected on the dust collecting electrode with high efficiency. If this dust collection electrode is transparent and flexible, and is movable from the outside through the collection container, after collecting an appropriate amount of suspended particulate matter, By moving the dust collection electrode, it is possible to easily pull out the part where suspended particulate matter was collected to the outside and draw the part that has not been collected into the collection container. Can be easily replaced. A laser diffraction / scattering particle size distribution measuring device is arranged adjacent to such a collecting device, and a transparent dust collecting electrode that collects suspended particulate matter and moves it outside the collecting container is used as a sample. Use as a holding member as it is, irradiate laser light for measurement from a laser diffraction / scattering particle size distribution measuring device, and measure the spatial intensity distribution of diffracted / scattered light by suspended particulate matter adhering to a transparent collection electrode. By measuring and measuring the particle size distribution of the suspended particulate matter, it is possible to continuously measure the transition of the particle size distribution of the suspended particulate matter over a long period of time with extremely simple work.
[0014]
In addition, as in the invention according to claim 2, if the film-shaped dust collecting electrode is wound up by the winding mechanism to substantially replace the dust collecting electrode, the unmanned operation can be performed. It is possible to continuously collect suspended particulate matter over a long period of time and measure the particle size distribution .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing a mechanical and optical configuration and a block diagram showing an electrical configuration.
[0016]
The collection container 1 includes a main body portion 11 and a bottom portion 12, and an air inlet 1 a is formed in the main body portion 11. Further, the bottom portion 12 is configured to move up and down by the opening / closing mechanism 2, and when the bottom portion 12 is raised, as shown in FIG. 1, the main body portion 11 and the bottom portion 12 have a flexible film-like dust collecting electrode to be described later. 6 is in a state of being closely contacted and airtightly joined, that is, the collection container 1 is closed. On the other hand, when the bottom portion 12 is lowered, a gap is formed between the main body portion 11 and the bottom portion 12. In this state, the film-like dust collecting electrode 6 can be moved.
[0017]
The bottom portion 12 is formed with a communication port 1b that communicates with the suction port of the pump 3 through the flexible tube 12a. Therefore, by driving the pump 3 with the bottom 12 raised to close the collection container 1, the atmosphere is sucked into the collection container 1 through the inflow port 1a.
[0018]
A discharge electrode 4 is provided on the upper portion of the main body 11 of the collection container 1. A high voltage from a high voltage power source 5 is applied to the discharge electrode 4. A flexible film-like dust collecting electrode 6 is disposed between the main body 11 and the bottom 12 of the collecting container 1. The film-like dust collecting electrode 6 is a transparent resin having an appropriate flexibility, such as polyurethane, with a conductive coating made of a transparent material on the surface thereof. It is connected to the ground potential 7 through a support member 6a made of a conductive material. Further, the film-like dust collecting electrode 6 has a width slightly longer than the dimension in the same direction of the collecting container 1 and a length sufficiently longer than the dimension, thereby closing the collecting container 1. Then, by being sandwiched between the main body portion 11 and the bottom portion 12, the airtightness between the two is maintained as described above, and both ends thereof are wound around the winding shafts 8 a and 8 b of the winding mechanism 8. By driving the winding mechanism 8, the film-like dust collecting electrode 6 is intermittently wound at a predetermined interval by a certain amount toward the left in the figure. In the figure, 8c, 8d and 8e are guide rolls.
[0019]
In the above configuration, when the pump 3 is driven with the collection container 1 closed to suck the atmosphere into the collection container 1 and a high voltage from the high voltage power source 5 is applied to the discharge electrode 4, the discharge electrode 4 is ionized to generate monopolar ions, which move toward the dust collecting electrode 6 due to a potential difference with the dust collecting electrode 6, and in the process, into the collecting container 1. It contacts and aspirates the suspended particulate matter P in the air that has been sucked. Similarly, the charged suspended particulate matter P is collected on the upper surface of the dust collection electrode 6 due to a potential difference with the discharge electrode 4. At this time, since the dust collecting electrode 6 is grounded, the potential of the dust collecting electrode 6 does not change even if a relatively large amount of the suspended particulate matter P is collected, and the suspended particles are highly efficient. The particulate matter P can be collected.
[0020]
Then, when the above collection operation is continued for a predetermined time set in advance, the pump 3 is stopped, and the bottom 12 of the collection container 1 is lowered by driving the opening / closing mechanism 2 and the winding mechanism 8. At the same time that the collection container 1 is opened, and then the dust collection electrode 6 is wound up, and the part that has been located in the collection container 1 and to which the suspended particulate matter P is attached is drawn out of the collection container 1. The unused portion is newly drawn into the collection container 1, and the bottom 12 is raised in this state to close the collection container 1 again.
[0021]
By repeating the above operation, the adhering regions of the suspended particulate matter P are formed on the film-like dust collecting electrode 6 at regular intervals in the longitudinal direction, and the suspended particulate matter P in the atmosphere is continuously formed. Can be collected.
[0022]
A laser diffraction / scattering particle size distribution measuring device 20 is disposed between the collection container 1 and the winding shaft 8a on the winding side of the winding mechanism 8. The laser diffraction / scattering type particle size distribution measuring apparatus 20 includes an irradiation optical system 21 that irradiates a portion of the film-like dust collecting electrode 6 that is drawn out of the collection container 1 to which the suspended particulate matter P is attached and a laser beam. Measurement optical system 22 for measuring the spatial intensity distribution of diffracted / scattered light due to suspended particulate matter P of laser light from optical system 21, data sampling circuit 23 for sampling the output of measurement optical system 22, and data sampling thereof The computer 24 is mainly configured to calculate the particle size distribution of the suspended particulate matter P adhering to the dust collecting electrode 6 using the spatial intensity distribution data of the diffracted / scattered light sampled by the circuit 23.
[0023]
The irradiation optical system 21 includes a laser light source 21a, a condenser lens 21b, a spatial filter 21c, and a collimator lens 21d, and irradiates the dust collection electrode 6 with a laser beam output from the laser light source 21a as a parallel light beam. This laser light is diffracted and scattered by the suspended particulate matter P adhering to the dust collecting electrode 6, and the spatial intensity distribution of the diffracted and scattered light is measured by the measurement optical system 22.
[0024]
The measurement optical system 22 includes a condenser lens 22a and a diffracted / forward scattered light sensor 22b disposed on the optical axis of the irradiation optical system 21 with the dust collecting electrode 6 interposed therebetween, and a front provided beside the condenser lens 22a. The wide-angle scattered light sensor group 22c and the side / backscattered light sensor group 22d provided closer to the irradiation optical system 21 than the dust collection electrode 6 are configured. The diffractive / forward scattered light sensor 22b is called a ring detector, and concentrically arranges light sensors having light receiving surfaces of different ring radii, ½ ring or ¼ ring. In this optical sensor array, it is possible to detect the intensity distribution for each minute angle of diffracted / scattered light within a predetermined forward angle collected by the condenser lens 22a. Accordingly, the spatial intensity distribution of the diffracted / scattered light by the suspended particulate matter P adhering to the dust collecting electrode 6 is measured in a wide range from the front minute angle to the rear by the measurement optical system 22 composed of these sensor groups. Is done.
[0025]
The light intensity detection signal for each diffraction / scattering angle by the measurement optical system 22 is amplified by the data sampling circuit 23 having the respective amplifiers and AD converters, digitized, It is taken into the computer 24 as spatial intensity distribution data of scattered light.
[0026]
The computer 24 uses the spatial intensity distribution data of the diffracted / scattered light to diffract the laser light by a calculation based on Mie's scattering theory and Fraunhofer's diffraction theory known in laser diffraction / scattering particle size distribution measurement. The particle size distribution of the suspended particulate matter P that is the cause particle that has been scattered is calculated.
[0027]
In the above configuration, ON / OFF of the pump 3 and application / stop of high voltage to the discharge electrode 4, opening / closing of the collection container 1, winding operation of the film-like dust collection electrode 6, and laser diffraction / scattering type particle size distribution By synchronizing the start / stop of the measuring device 20, suspended particulate matter in the atmosphere can be collected continuously under substantially unattended operation, and the particle size distribution can be automatically measured.
[0028]
【The invention's effect】
As described above, according to the collection and measurement apparatus of the present invention, the atmosphere is sucked into the collection container, and the suspended particulate matter contained in the atmosphere is charged by the discharge electrode provided in the collection container. by collected on the dust collecting electrode, as a dust collecting electrode, used as the film-like transparent which can be moved from the outside through the container, moving the dust collecting electrode at a predetermined timing Makes it possible to substantially replace the dust collection electrode in the collection container, continuously collect suspended particulate matter in the atmosphere, and move the transparent electrode moved out of the collection container. Diffraction / scattered light caused by suspended particulate matter adhering to the dust collection electrode by irradiating the film-shaped dust collection electrode as a sample holding member and irradiating it with laser light for measurement by a laser diffraction / scattering particle size distribution measuring device By measuring the particle size distribution While achieving significant labor saving or unmanned, it is possible to continuously measure the particle size distribution of suspended particulate matter in the air.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing a mechanical and optical configuration and a block diagram showing an electrical configuration.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Collection container 1a Inflow port 1b Communication port 11 Main-body part 12 Bottom part 2 Opening-closing mechanism 3 Pump 4 Discharge electrode 5 High voltage power supply 6 Film-shaped dust collection electrode 7 Grounding potential 8 Winding mechanism 20 Laser diffraction and scattering type particle size distribution measuring apparatus 21 irradiation optical system 22 measurement optical system 23 data sampling circuit 24 computer P suspended particulate matter

Claims (2)

An apparatus for collecting and measuring suspended particulate matter contained in the atmosphere, comprising a collection container, a pump for sucking air into the collection container, and a monopolar ion disposed in the collection container A discharge electrode that charges the suspended particulate matter in the container and the dust collection that attracts and collects the suspended particulate matter charged in the collection container by applying a potential difference to the discharge electrode A collecting device comprising an electrode, and a measuring device arranged adjacent to the collecting device and measuring the suspended particulate matter collected by the collecting device,
The dust collecting electrode of the collecting device is a transparent and flexible film-like member provided with a conductive coating, and is disposed so as to be movable from the outside through the collecting container. Irradiates laser light using the dust collection electrode drawn out of the collection container of the collection device as a sample holding member, and the spatial intensity distribution of the diffracted / scattered light due to suspended particulate matter adhering thereto. An apparatus for collecting and measuring suspended particulate matter, which is a laser diffraction / scattering particle size distribution measuring device that measures and calculates the particle size distribution of the suspended particulate matter. And characterized in that by winding the fill beam-shaped dust collecting electrodes, pull the sites were collected suspended particulate matter out of the container, and a take-up mechanism to pull a portion of the non-collecting in the container The apparatus for collecting and measuring suspended particulate matter in the atmosphere according to claim 1.

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