JP4732952B2 - Fine particle classifier - Google Patents

Description

  The present invention relates to a fine particle classifying device for classifying fine particles that have a particle size distribution with a predetermined width (particularly, a nano-sized width) in a gas phase, and in particular, a single device floats in the gas phase. The present invention relates to a fine particle classification apparatus capable of simultaneously selecting a plurality of types of fine particles having different particle diameters from among the fine particles to be processed.

  In recent years, health damage due to suspended particles contained in the exhaust gas of automobiles, especially diesel vehicles, has been a problem, and studies have been made to reduce the number concentration of exhaust particles due to improvements in engine structure, fuel, and catalyst. ing.

  Diesel exhaust particles can be divided into nuclei mode particles having a peak in a particle size region of 50 nm or less and accumulation mode particles having a peak in a particle size region of 50 nm or more. Among these, nuclei mode particles centered on particles around 10 nm, unlike particles of 0.1 μm or more, reach the deep inside of the alveoli and cause serious damage to the human body due to direct entry into the blood. It is said. Moreover, it is known that nuclei mode particles account for 90% or more of diesel exhaust particles in terms of the number of particles, and sufficient results have not been achieved for nuclei mode particles even by the study for reducing exhaust particulates.

  Conventional analysis methods for such fine particles include (1) a gravimetric method of collecting fine particles in exhaust gas per fixed time on a filter and measuring the weight, and (2) a laser beam etc. on the fine particles. Optical method to obtain particle size distribution (relationship between particle size and number concentration) from scattered light intensity and transmittance, etc., and (3) Electric transfer of charged fine particles floating in gas in electric field A technique using a differential electric mobility measuring device (DMA / Differential Mobility Analyzer) that measures the particle size of fine particles by utilizing the property that the degree depends on the particle size is known.

  However, among the conventional analysis methods described above, the weight measurement method of (1) requires a long time for measurement, and there is a problem that the amount of particles collected varies depending on the filtration efficiency of the filter. In the optical method, since the scattered light intensity and the like are proportional to the sixth power of the particle size of the fine particles, there is a problem that the measurement accuracy decreases in a minute particle size region. Note that all commonly used particle counters are intended for relatively large particles with a particle size of sub-micrometer size or larger, and have a nanometer size that floats in the exhaust gas of automobiles or in the atmosphere. It was impossible to analyze fine particles in real time.

  On the other hand, the DMA of (3) is currently the only device that can observe the particle size distribution of nanometer-sized fine particles in situ, but the current DMA measures the concentration of stationary particles. Therefore, there is a problem that effective vehicle exhaust gas measurement cannot be performed. That is, while the number concentration and distribution of automobile exhaust particles change depending on driving conditions such as acceleration, the current DMA can measure unsteady particle concentrations that change transiently under driving conditions in real time. Can not.

  In addition, with conventional measurement techniques including DMA, it is difficult to simultaneously measure the transient response of fine particles in two different particle size regions such as nuclei mode particles and accumulation mode particles.

Patent Document 1 discloses a fine particle analyzer that solves the above problems. That is, the fine particle analyzer of Patent Document 1 is a DMA having a triple cylindrical structure including a center electrode portion, a common electrode portion, and an outer electrode portion, and forms a first measurement region between the center electrode portion and the common electrode portion. In addition, the second measurement region is formed between the common electrode portion and the outer electrode portion, and the particle size distribution of fine particles having a wide distribution by a single device and without significantly increasing the device size. (Relationship between particle size and number concentration) and changes over time in the number concentration of fine particles having a specific particle size can be divided into two particle size ranges and simultaneously measured in real time.
JP 2005-214931 A

  As described above, the fine particle analyzer of Patent Document 1 can simultaneously measure the number concentration of fine particles in two types of particle size ranges simultaneously and in real time. It is difficult to increase.

  The present invention has been made in view of the above-described circumstances, and achieves one or more of the following objects.

  That is, an object of the present invention is to provide a fine particle classification device that can simultaneously classify fine particles having three or more different particle sizes with a single device without greatly increasing the device size.

  Another object of the present invention is to provide a plurality of particles having different particle sizes from among particles suspended in the gas phase, having a smaller or simpler device configuration than the particle classifier provided in the particle analyzer of Patent Document 1. It is an object of the present invention to provide a fine particle classifying apparatus capable of classifying particles simultaneously.

  Still another object of the present invention is to manufacture a simple structure with a small number of parts, and to simultaneously classify particles having a plurality of different particle sizes from particles floating in the gas phase. The object is to provide a fine particle classifier.

  Still another object of the present invention is to provide a fine particle classification device capable of classifying fine particles having a specific particle size with high accuracy by suppressing the movement of fine particles in the circumferential direction.

The present invention solves the above problems,
A surrounding external electrode portion having an inner peripheral side surface formed in a cylindrical shape;
A central electrode portion disposed concentrically with an inner peripheral side surface of the external electrode portion;
A cylindrical particle size selection space formed between the outer peripheral side surface of the center electrode portion and the inner peripheral side surface of the external electrode portion,
A large number of charged fine particles are introduced into the particle size selection space from the outside of the apparatus through a particle introduction slit formed above the particle size selection space, and a sheath gas is formed above the particle introduction slit. A sheath gas is supplied to the particle size selection space through the supply unit so as to move the charged fine particles introduced into the particle size selection space from the outside of the apparatus downward, and between the center electrode portion and the external electrode portion. In addition, when a predetermined voltage is applied to move the charged fine particles introduced into the particle size selection space from the inner peripheral side surface to the outer peripheral side surface, the charged fine particles introduced into the particle size selection space A fine particle classifying device that captures charged fine particles having a specific particle diameter in a fine particle outlet slit formed on the outer peripheral side surface,
The center electrode part is a plurality of partial columnar center electrode parts each having a cylindrical shape whose upper and lower surfaces are fan-shaped, and the particle size selection space is a plurality of particle size selection spaces for each particle diameter center electrode part. And a shielding member partitioned into
The fine particle classifying apparatus (Claim 1), wherein the fine particle derivation slits are individually formed in each of the particle size-specific center electrode portions.

  According to the present invention, the center electrode portion has a plurality of center electrode portions by particle size, and the particle outlet slits are individually formed in each of the center electrode portions by particle size. It is possible to classify (fine particle size sorting) fine particles having a particle size of 1 mm at the same time. In addition, by adopting the same double structure as the conventional differential electrostatic classifier with a double-cylindrical structure that classifies only one kind of fine particles, the fine particles floating in the gas phase with a single device Among them, a fine particle classifier capable of simultaneously classifying fine particles having two or more different particle sizes can be manufactured in the same or substantially the same size as a conventional differential electrostatic classifier. In addition, the fine particle classifier of the present invention has an advanced processing technology because the external electrode portion has a simple surrounding shape, and the central electrode portion is formed by simple constituent elements of a particle size-specific central electrode portion and a shielding member. It is possible to manufacture without requiring a complicated mold, and the manufacturing cost of the apparatus can be reduced. In addition, according to the present invention, the movement of the fine particles introduced into the apparatus by the shielding member in the circumferential direction can be suppressed, whereby fine particles having a specific particle size can be classified with high accuracy. It becomes.

  In the present invention, it is preferable that the center electrode portions for each particle diameter are formed to have different outer diameter dimensions (claim 2).

  In this invention, since each central electrode part for each particle size has a different outer diameter size, the width size of the selection space for each particle size is different. Different types of fine particles can be selected.

  In the present invention, it is preferable that the fine particle derivation slits are formed at different heights on the outer peripheral side surface of the center electrode portion.

  In such an invention, since the installation height of each particle outlet slit is different, the distance in the height direction from the inlet slit to the particle outlet slit is different for each central electrode part for each particle size. Based on this, it is possible to select a plurality of types of fine particles having different particle diameters.

  It is particularly preferable that both the outer diameter size of each central electrode part for each particle size and the installation height of each particle outlet slit are different for each central electrode part for each particle size. Can be adjusted in a wider range.

  In the present invention, the fine particle introduction slit has an annular shape along the inner peripheral side surface of the external electrode portion, and the fine particle lead-out slit is the center electrode for each particle diameter formed by each. It is preferable to form the circular-arc form along the outer peripheral side surface of a part (Claim 4).

  In such an invention, fine particles having a specific particle size are formed in an arc shape along the outer peripheral side surface of the central electrode portion for each particle size from among the fine particles uniformly introduced into the apparatus in the circumferential direction from the fine particle introduction slit. The collected particles can be efficiently collected by the particle outlet slit, thereby enabling efficient classification.

  In the present invention, it is preferable that an excess gas discharge section for discharging excess gas to the outside is formed for each of the particle size spaces partitioned by the shielding member.

  In such an invention, the excess gas after classification can be discharged to the outside of the apparatus for each particle size space, so that the time during which the excess gas stays for each particle size space can be shortened as much as possible. This makes it possible to classify with high accuracy.

  In the present invention, the shielding member is an insulator that insulates the particle size central electrode portions from each other, and there is a different potential difference between the external electrode portion and the particle size central electrode portion. (Claim 6).

  In this invention, since the potential difference between the external electrode part and each central electrode part for each particle size can be controlled independently, the particle size of the fine particles classified in each central electrode part for each particle size can be controlled independently. It becomes possible to do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing a configuration of a differential electrostatic classifier 1 to which the present invention is applied. This differential electrostatic classifier 1 is a single particle classifier configured to classify fine particles having two different particle sizes from fine particles floating in a gas phase at the same time. is there.

  The differential electrostatic classifier 1 is roughly provided with a center electrode part 10, an external electrode part 20, an aerosol introduction part 30, a cover part 40, a base part 50, a common plate 60, and a laminator 70.

  In other words, in the differential electrostatic classification device 1, a tubular specific fine particle outlet tube 51 (51 a, 51 b) for classifying charged fine particles having a specific particle size and leading them out of the device and the classified device inside. The columnar-shaped center electrode portion 10 is fitted in the center of the upper surface of the base portion 50 where the tubular excess gas discharge pipe 52 (52a, 52b) for discharging surplus gas staying outside the device is formed. A surrounding external electrode portion 20 having an inner peripheral side surface formed in a cylindrical shape is attached to the peripheral portion of the upper surface of the base portion 50. The external electrode portion 20 has an inner peripheral side surface that is concentric with the central electrode portion 10 (more precisely, curvatures of outer peripheral side surfaces 14a and 14b of first and second central electrode portions 10a and 10b described later). Surrounding the lower region of the center electrode portion 10 (so that the center coincides with the central axis of the inner peripheral side surface of the outer electrode portion 20), the inner peripheral side surface of the outer electrode portion 20 and the outer peripheral side surface of the central electrode portion 10 A cylindrical particle size sorting space S is formed therebetween.

  In addition, the center electrode portion 10 classifies the fine particles having a specific particle diameter and leads them to the outside of the apparatus, and the specific particle lead slit portions 11 (11a and 11b) formed in a slit shape on the outer peripheral side surface, It has a tubular specific fine particle lead-out path 12 (12a, 12b) drilled in the center electrode portion 10 so as to communicate with the specific fine particle lead slit portion 11 (11a, 11b).

  Further, the particle size selection space S is externally provided between the upper surface of the external electrode portion 20 attached to the base portion 50 and the outer peripheral side surface of the central electrode portion 10 so as to surround the upper region of the central electrode portion 10. An enveloped aerosol introduction part 30 is mounted, in which an inner peripheral side surface forming a cylindrical sheath gas guide space S3 for guiding a supplied sheath gas, which will be described later, is formed in a substantially cylindrical shape.

  The aerosol introduction unit 30 introduces an aerosol gas containing charged fine particles having a certain particle size distribution to be classified into the apparatus from the outside of the apparatus (particularly, in the cylindrical particle size selection space S, In order to introduce uniformly from the direction), a tubular aerosol introduction pipe 31 drilled from the outer peripheral side surface of the introduction part 30 to a predetermined position inside the introduction part 30, and the aerosol introduction pipe 31 communicated and introduced An aerosol buffer portion 32 formed in a donut shape inside the portion 30, and an aerosol introduction slit portion 33 that is communicated with the aerosol buffer portion 32 and formed annularly along the inner peripheral side surface of the introduction portion 30. Yes.

  Further, the upper surface of the electrode 13 (including the first electrode 13 a and the second electrode 13 b) formed on the outer peripheral edge of the upper surface of the center electrode unit 10 mounted on the base unit 50, and the external electrode unit 20 on the base unit 50 are mounted. The laminator 70 for adjusting the flow of the sheath gas supplied from the cover portion 40 to be described later to the sheath gas guide space S3 is fitted into the concave portion formed from the upper surface of the aerosol introduction portion 30, and the laminator 70 is further fitted. An enveloping cover portion 40 having an inner peripheral surface formed in a cup shape is attached to the upper surface of the aerosol introduction portion 30 so as to sandwich the peripheral edge portion with the aerosol introduction portion 30. In addition, a plate-like common plate 60 that serves as a lid of the apparatus housing is mounted on the upper surface of the cover portion 40.

  The cover 40 is formed from outside with a sheath gas (in particular, above the particle size selection space S) for applying a constant direction (downward) velocity to the aerosol gas supplied to the inside of the apparatus. In order to supply to the sheath gas guide space S3), a tubular sheath gas supply pipe 41 drilled from the outer peripheral side surface of the cover portion 40 to the inner peripheral side surface of the cover portion 40, and the sheath gas supply tube 41 communicate with the laminar. A cylindrical sheath gas buffer portion 42 is formed between the two and 70.

  Next, the center electrode portion 10 will be described in more detail with reference to FIG.

  2A is a perspective view of the center electrode portion 10 viewed from the upper right oblique direction, and FIG. 2B is a cross-sectional view of the differential electrostatic classifier 1 taken along line BB in FIG. (C) has shown the side view of each component of the center electrode part 10. FIG.

  The center electrode portion 10 includes a first center electrode portion 10a, a second center electrode portion 10b, and a shielding plate 10c. The center electrode portion 10 is composed of a first center electrode portion 10a and a second center electrode portion 10b each having a partial cylindrical shape (in this case, a substantially semi-cylindrical shape) obtained by cutting two cylinders having different diameters in the longitudinal direction. A flat shield plate 10c is sandwiched.

  Here, the shielding plate 10c includes a first particle size selection space S1 on the first center electrode portion 10a side and a second particle size selection space S2 on the second center electrode portion 10b side. It is a member for partitioning into two spaces. The shielding plate 10 c has a height dimension and a width dimension that can completely partition the particle size selection space S below at least the aerosol introduction slit portion 33.

  Further, the shielding plate 10c is configured, for example, by sandwiching a central plate 11c made of SUS316 or the like between two insulating plates 12c and 13c made of ABS or the like. Thereby, it is possible to electrically insulate the first center electrode portion 10a and the second center electrode portion 10b and apply different voltages to each.

  The first center electrode portion 10a and the second center electrode portion 10b classify fine particles having different particle diameters for each of the first particle size selection space S1 and the second particle size selection space S2 and derive them outside the apparatus. The first specific particle derivation slit portion 11a and the second specific particle derivation slit portion 11b, and the first specific particle derivation slit portion 11a and the second specific particle derivation slit portion 11b, respectively, communicated with each other. The first specific fine particle lead-out path 12a and the second specific fine particle lead-out path 12b are provided.

  The first specific fine particle derivation slit portion 11a and the second specific fine particle derivation slit portion 11b are formed at different height positions in order to classify specific fine particles having different particle sizes.

  Generally, in this type of differential electrostatic classifier, the width of the particle size selection space (difference between the outer diameter of the central electrode part and the inner diameter of the external electrode part), from the aerosol introduction slit part to the specific particle outlet slit part It is possible to adjust the particle diameter of the fine particles to be captured in the fine particle derivation slit portion by parameters such as the distance in the height direction of the first electrode and the potential difference between the center electrode portion and the external electrode portion.

  In this regard, in the present embodiment, (1) the outer diameter (R1) of the first center electrode portion 10a and the outer diameter (R2) of the second center electrode portion 10b are set to different dimensions, and ( 2) Height direction distance (L1) from the aerosol introduction slit part 33 of the aerosol introduction part 30 to the first specific fine particle derivation slit part 11a, and the second specific fine particle derivation from the aerosol introduction slit part 33 of the aerosol introduction part 30 By setting the height direction distance (L2) to the slit portion 11b to be different dimensions, fine particles having different particle diameters are captured by the first and second specific fine particle derivation slit portions 11a and 11b. .

  More specifically, by setting the dimensions such that R1 <R2 and L1 <L2, fine particles having a smaller particle diameter are captured in the first specific fine particle derivation slit portion 11a, and the second specific fine particle derivation slit is obtained. Fine particles having a larger particle diameter are captured in the portion 11b.

  Strictly speaking, the outer peripheral side surfaces 14a and 14b of the first and second center electrode portions 10a and 10b in the present embodiment are centered on the axis of the differential electrostatic classifier 1 (the center position O of the shielding plate). The outer shapes (R1, R2) of the first and second center electrode portions 10a, 10b described above correspond to the radii of curvature of the outer peripheral side surfaces 14a, 14b. In other words, the first and second center electrode portions 10a and 10b each divide a cylinder having radii R1 and R2 into two planes including the central axis, and further, from the plane, 1 / th of the thickness (r) of the shielding plate 10c. The thickness (1 / 2r) of 2 is excised.

  FIG. 3 shows enlarged views of the two-dot chain line ellipse portion X and the two-dot chain line ellipse portion Y shown in FIG. As shown in FIGS. 3 (a) and 3 (b), by setting R1, R2, L1, and L2 to the above relationship, the aerosol introduction slit portion 33 is directed to the first specific particle outlet slit portion 11a. The angle formed by the direction with the vertical direction is larger than the angle formed by the direction from the aerosol introduction slit portion 33 toward the second specific fine particle extraction slit portion 11b with the vertical direction. For this reason, when the potential difference between the external electrode portion 20 and the first and second center electrode portions 10a and 10b is the same, fine particles having a small particle diameter that increase acceleration in the horizontal direction due to the potential difference are the first. The fine particles having a large particle diameter which are captured by the first specific fine particle derivation slit portion 11a and whose acceleration is reduced are captured by the second specific fine particle derivation slit portion 11b.

  Further, in the differential electrostatic classification device 1 of the present embodiment, since the first and second center electrode portions 10a and 10b are electrically insulated by the shielding plate 10c, the terminal members Ta, Tb and the first Different voltages can be applied to both the central electrode portions 10a and 10b via the electrode 13a and the second electrode 13b, and the first and second specific fine particle derivation slit portions 11a can be applied depending on the applied voltages. , 11b, the particle size of the fine particles captured can be adjusted.

  The base unit 50 shown in FIG. 1 includes first and second specific particle recovery units 51a and 51b communicating with the first and second specific particle outlet channels 12a and 12b, and first and second particle size selections. First and second excess gas discharge pipes 52a and 52b communicating with the spaces S1 and S2 are formed, and the fine particles captured by the first and second specific fine particle derivation slit portions 11a and 11b are respectively first. It is possible to measure the number concentration of the fine particles collected by the second specific fine particle collecting units 51a and 51b, and the aerosol gas containing fine particles not to be captured is discharged from the first and second excess gases. The pipes 52a and 52b are discharged out of the apparatus.

  In the differential electrostatic classification device 1 in the above embodiment, for example, the first center electrode portion 10a and the second center electrode portion 10b, the external electrode portion 20, the aerosol introduction portion 30, the cover portion 40, and the laminator 70 are ABS or the like. The base portion 50, the common plate 60, the first electrode 13a, and the second electrode 13b are formed of a metal material such as SUS316, and the first center electrode portion 10a and the second center electrode portion 10b. It is possible to impart necessary conduction characteristics by performing gold plating on the surfaces of the external electrode unit 20 and the aerosol introduction unit 30, thereby reducing the manufacturing cost and manufacturing of the differential electrostatic classification device 1. Simplification can be achieved.

  According to the configuration described above, since a double structure similar to a differential electrostatic classifier having a double cylindrical structure that classifies only fine particles having one type of particle diameter is employed, the difference is different in a single apparatus. A differential electrostatic classifier capable of simultaneously selecting two types of fine particles having a particle size can be manufactured in the same or substantially the same size as the differential electrostatic classifier having the double cylindrical structure.

  In addition, according to the above configuration, since the external electrode portion has a simple surrounding shape, and the central electrode portion is formed by simple components of two particle size-specific central electrode portions and a shielding plate, advanced processing technology is used. Thus, a differential electrostatic classification device that can be manufactured without requiring a complicated mold is realized.

  Further, according to the above configuration, since the shielding plate is provided, it is possible to suppress the movement of the fine particles introduced into the apparatus in the circumferential direction in the particle size selection space. Diameter selection can be performed.

  Next, a modification of the center electrode unit 10 of the differential electrostatic classifier 1 will be described with reference to FIG. That is, in the above-described embodiment, a mode in which two types of fine particles having different particle diameters are classified simultaneously with one differential electrostatic classifier has been described. However, the present invention is not limited to this, and the center electrode portion 10 By changing the configuration, it is possible to provide a differential electrostatic classification device that can simultaneously classify three or more kinds of fine particles having different particle sizes.

  FIG. 4 shows a configuration of the center electrode unit 100 for simultaneously classifying three kinds of fine particles having different particle diameters with one differential electrostatic classifier.

  The center electrode portion 100 includes a first center electrode portion 100a, a second center electrode portion 100b, a third center electrode portion 100d, a first shielding plate 100c, and a second shielding plate 100e. It is prepared and configured.

  That is, the center electrode portion 100 has a configuration for partitioning the particle size selection space S into individual spaces for each center electrode portion, like the above-described center electrode portion 10. Specifically, the particle size selection space S includes a first particle size selection space S10 for the first center electrode portion 100a, a second particle size selection space S20 for the second center electrode portion 100b, The first shielding plate 100c and the second shielding plate 100e are provided as members having shapes and dimensions that can be divided into three spaces of the third particle size selection space S30 for the three central electrode portions 100d.

  The first to third center electrode portions 100a, 100b, and 100d include first to third specific fine particle derivation slit portions 111a, 111b, and 111d for classifying fine particles having different particle sizes, respectively. First to third specific fine particle outlets 120a, 120b, and 120d that are in communication are provided.

  And the 1st-3rd center electrode part 100a, 100b, and 100d are made into the dimension from which the outer diameter (R1-R3) differs, respectively, and also from the aerosol introduction slit part 33, it is 1st-3rd specification. The first to third specific particle derivation slit portions 111a, 111b, and 111d are first to first so that the height direction distances (L1 to L3) to the particle derivation slit portions 111a, 111b, and 111d have different dimensions. 3 center electrode portions 100a, 100b and 100d are formed at different height positions.

  With such a configuration, a differential electrostatic classification device capable of simultaneously classifying fine particles having three different particle sizes from fine particles floating in the gas phase with a single device is manufactured in a small size. It is possible.

  In the example of the center electrode unit 100 shown in FIG. 4, one space obtained by dividing the particle size selection space S into two equal parts becomes the second particle size selection space S20, and the other space divided into two parts is the first space. The first and third particle size selection spaces S10 and S30 have been shown. The space obtained by dividing the particle size selection space S into three equal parts is configured as the first to third particle size selection spaces S10 to S30. The aspect of the partition of the particle size sorting space S is arbitrary.

  In the above-described embodiment, a differential electrostatic classifier that can simultaneously classify fine particles having two or three types of particle diameters is shown as an example. However, the particle size selection space S can be arbitrarily defined by the center electrode portion (shielding plate). It is possible to provide a differential electrostatic classifier capable of classifying fine particles having an arbitrary number of different particle diameters simultaneously by dividing the number of particles, and even if the types of particle diameters to be classified increase, The device size does not increase significantly.

  Finally, a DMA (Differential Mobility Analyzer) system in which the differential electrostatic classifier according to the present invention is mounted will be described.

  FIG. 5 is a diagram showing a configuration example of a DMA system in which the differential electrostatic classifier shown in FIG. 1 is mounted. The DMA system 200 is a system that classifies fine particles that have a particle size distribution with a predetermined width (particularly nano-size) in the gas phase and measures the particle size distribution of the fine particles.

  The DMA system 200 includes, for example, the differential electrostatic classifier 1 described above, a first fine particle number concentration counter 210a having a first Faraday cup 211a and a first electrometer 212a, and a second Faraday cup. 211b, a second particle number concentration counter 210b having a second electrometer 212b, a particle charging device 220, a particle supply device 230, a gas supply device 240, a first gas flow rate controller 250, a second Gas flow rate controller 260, vacuum pump 270, pressure controller 280, first valve 290a, second valve 290b, first power source 300a, and second power source 300b.

  That is, the DMA system 200 supplies (1) a sheath gas Sg serving as a carrier gas supplied via the first gas flow rate controller 250 to the differential electrostatic classifier 1.

  Also, (2) an aerosol gas Ag (automobile including fine particles to be measured for particle size distribution) supplied by the fine particle supply device 230 by a carrier gas supplied by the gas supply device 240 via the second gas flow rate controller 260 In the fine particle charging device 220, and in the fine particle charging device 220, the aerosol gas Ag is generated by alpha rays emitted from a radiation source such as americium 241, corona ions generated by a corona discharger, and the like. The contained fine particles are charged in advance, and the charged charged fine particles are supplied to the differential electrostatic classifier 1.

  (3) The differential electrostatic classifier 1 classifies fine particles having a specific particle size from among the charged fine particles contained in the introduced aerosol gas Ag and derives them to the fine particle number concentration counter 210 (210a, 210b). To do. That is, fine particles of a specific size selected in the first particle size selection space S1 are derived to the first fine particle number concentration counter 210a via the first specific fine particle extraction slit 11a and the first specific fine particle extraction path 12a. At the same time, fine particles of a specific size selected in the second particle size selection space S2 are sent to the second fine particle number concentration counter 210b via the second specific fine particle extraction slit 11b and the second specific fine particle extraction path 12b. To derive. Accordingly, it is possible to simultaneously measure the concentration distribution of two kinds of fine particles using the first fine particle number concentration counter 210a and the second fine particle number concentration counter 210b.

  (4) The differential electrostatic classification device 1 discharges excess gas Eg in the device to the outside of the device. That is, in this case, the excess gas Eg in the first particle size sorting space S1 is discharged to the outside of the apparatus through the first excess gas discharge pipe 52a of the base portion 50, and the second particle size sorting space S2 is used. The excess gas Eg is discharged to the outside of the apparatus through the second excess gas discharge pipe 52b of the base portion 50.

  A pressure controller 9 is disposed on the exhaust side of the excess gas Eg of the differential electrostatic classifier 1 to control the pressure in the differential electrostatic classifier 1. In addition, first and second valves 290a and 290b are arranged on the exhaust sides of the first and second Faraday cups 211a and 211b, respectively, to control the pressure in both Faraday cups.

  By applying the differential electrostatic classifier 1 according to the present invention to such a DMA system 200, the particle size distribution (particle size) of the fine particles contained in the measurement target gas in two (or more) particle size regions. And the number concentration) can be measured simultaneously. Specifically, by individually scanning the voltage applied to each center electrode portion, for example, one particle number concentration measuring instrument 210a measures the particle size distribution in a small particle size region such as 5 to 50 nm, and the other In the fine particle number concentration counter 210b, the particle size distribution in a large particle size region such as 50 to 500 nm can be measured.

  Alternatively, it is also possible to perform measurement with a fixed voltage applied to each particle size center electrode. In this case, the fine particle number concentration measuring device 210a continuously measures the concentration of fine particles having a specific particle size such as 10 nm over a predetermined time, and the other fine particle number concentration measuring device 210b measures another concentration such as 200 nm. The concentration of fine particles having a specific particle diameter can be continuously measured over a predetermined time. Therefore, for example, it is possible to facilitate the measurement of the transient response of the number-based concentration of nuclei mode particles and accumulation mode particles of automobile exhaust gas whose particle distribution changes transiently depending on operating conditions such as acceleration.

  According to the fine particle classifying apparatus of the present invention or the DMA system 200 using the same, a plurality of types of gas from various measurement target gases such as automobile exhaust gas, urban air, atmosphere in a manufacturing factory of precision equipment such as semiconductors, etc. It is possible to classify fine particles having a particle size or to measure the concentration of the fine particles efficiently.

  The present invention has been described based on the exemplary embodiments. However, the present invention is not limited to the above embodiments, and various changes and modifications can be made within the scope of the claims. is there.

  For example, in the above embodiment, since each of the plurality of center electrode parts by particle size is electrically insulated and a different voltage can be applied to each, the particle size of fine particles to be classified is set. Although the differential electrostatic classifier that can be adjusted by the voltage applied to each particle size center electrode portion has been described as an example, the insulation of each particle size center electrode portion is not the essence of the present invention, It is also possible to configure such that the central electrode part by particle size or a part thereof is electrically connected to each other.

  In the above embodiment, a plurality of excess gas discharge pipes for discharging excess gas are formed in the base portion for each individual space partitioned by the shielding plate. It is also possible to share the excess gas discharge pipe.

  Further, in the above-described embodiment, the base part 50, the external electrode part 20, and the aerosol introduction part made up of individual parts have been described. However, other than this, for example, if the base part 50 can be manufactured easily and inexpensively, the base part Any or all of the part 50, the external electrode part 20, and the aerosol introduction part 30 may be integrally formed.

  Moreover, the external appearance shape (cuboid shape shown in FIG. 5) of the differential electrostatic classifier in the above embodiment is described as an example only, and other than this, for example, a cylindrical shape, a barrel shape, a bowl shape, etc. Other shapes may be used, and the present invention does not exclude a differential electrostatic classifier having an appearance shape different from that of the above embodiment.

It is sectional drawing of the differential electrostatic classification apparatus to which this invention is applied. It is explanatory drawing explaining the structure of the center electrode part of FIG. It is an enlarged view which shows the mode of expansion of the predetermined part of FIG. It is explanatory drawing explaining the structure of the modification of the center electrode part of FIG.1 and FIG.2. It is explanatory drawing explaining the structure of the DMA system by which the differential electrostatic classification device to which this invention is applied is mounted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Differential electrostatic classification apparatus 10 ... Center electrode part 10a ... 1st center electrode part 11a ... 1st specific particle derivation | leading-out slit part 12a ... 1st specific particle derivation | leading path 13a ... 1st electrode 10b ... 2nd Central electrode portion 11b ... second specific particle outlet slit portion 12b ... second specific particle outlet passage 13b ... second electrode 10c ... shielding plate 11c ... center plate 12c, 13c ... insulating plate 20 ... external electrode portion 30 ... aerosol Introduction part 31 ... Aerosol introduction pipe 32 ... Aerosol buffer part 33 ... Aerosol introduction slit part 34 ... Inner peripheral side surface 40 ... Cover part 41 ... Sheath gas supply pipe 42 ... Sheath gas buffer part 50 ... Base part 51a ... First specific particulate collection Part 51b ... Second specific particulate collection part 52a ... First excess gas discharge pipe 52b ... Second excess gas discharge pipe 60 ... Common Rate 70 ... laminar S ... grain 径選 another space S1 ... first particle 径選 another space S2 ... second particle 径選 by space

Claims (6)

A surrounding external electrode portion having an inner peripheral side surface formed in a cylindrical shape;
A central electrode portion disposed concentrically with an inner peripheral side surface of the external electrode portion;
A particle size selection space formed between the outer peripheral side surface of the center electrode portion and the inner peripheral side surface of the external electrode portion,
A large number of charged fine particles are introduced into the particle size selection space from the outside of the apparatus through a particle introduction slit formed above the particle size selection space, and a sheath gas is formed above the particle introduction slit. A sheath gas is supplied to the particle size selection space through the supply unit so as to move the charged fine particles introduced into the particle size selection space from the outside of the apparatus downward, and between the center electrode portion and the external electrode portion. In addition, when a predetermined voltage is applied to move the charged fine particles introduced into the particle size selection space from the inner peripheral side surface to the outer peripheral side surface, the charged fine particles introduced into the particle size selection space A fine particle classifying device that captures charged fine particles having a specific particle diameter in a fine particle outlet slit formed on the outer peripheral side surface,
The center electrode part is a plurality of partial columnar center electrode parts each having a cylindrical shape whose upper and lower surfaces are fan-shaped, and the particle size selection space is a plurality of particle size selection spaces for each particle diameter center electrode part. And a shielding member partitioned into
The fine particle classifying apparatus, wherein the fine particle derivation slits are individually formed in each of the particle size-specific center electrode portions.   2. The fine particle classifying apparatus according to claim 1, wherein each of the central electrodes for each particle diameter is formed to have a different outer diameter.   The fine particle classification apparatus according to claim 1 or 2, wherein the fine particle extraction slits are formed at different heights on the outer peripheral side surface of the central electrode portion. The fine particle introduction slit has an annular shape along the inner peripheral side surface of the external electrode portion,
The said fine particle extraction slit has comprised the circular arc form along the outer peripheral side surface of the said center electrode part according to each said particle size in which each is formed, The Claim 1 characterized by the above-mentioned. The fine particle classifier described.   The excess gas discharge part which discharges | emits excess gas outside is formed for every said particle size space divided by the said shielding member, The Claim 1 characterized by the above-mentioned. Fine particle classifier. The shielding member is an insulator that mutually insulates the central electrode parts according to the respective particle sizes,
6. The fine particle classifier according to claim 1, wherein different potential differences are provided between the external electrode part and the central electrode part for each particle diameter.

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