JP6392112B2 - Linear cyclone type sizing unit and sizing device, and method for measuring airborne dust concentration - Google Patents

Description

  The present invention relates to a rectilinear cyclone type sizing unit that is attached to a suction device and sizing dust in air that has been sucked. The present invention also relates to a sizing apparatus having the sizing unit. Moreover, it is related with the method of measuring an air | atmosphere dust density | concentration using the said particle size collection apparatus. More specifically, for example, a sizing unit of a sizing device suitable for measurement of air dust concentration up to about PM2.5 or PM10, which has been a problem in recent years, and a measuring method using the sizing unit Is to provide.

  In grasping the state of air contaminated with dust, also called particulate matter, it is an important index to grasp the concentration of air dust of a specific size in the air. This is because dust of the size of about PM2.5, PM4, and PM10 may be deposited on the respiratory system such as the human lungs depending on the size of each, and may have a significant effect on health. This is also an important point of view because the influence on the human body varies. As a typical method for measuring the air dust concentration, a filter weighing method is known in which the change in weight of a filter is measured when air is sucked and particulate matter is filtered and collected on the filter. In the filter weighing method, it is required to pre-size the size of the particulate matter collected by the filter. Examples of this sizing method include a multistage sizing device using gravity sedimentation, a cyclone sizing device using centrifugal force, and a collision collecting sizing device (impactor).

  For example, Patent Document 1 relates to a PM2.5 classifier using a high volume air sampler. The technique disclosed in Patent Document 1 relates to a collision collection type sizing device using a collision plate. However, the collision collecting type sizing apparatus has a problem that it may be scattered again after the collision, and the suction resistance during operation of the apparatus is large.

  A cyclone type suction device is known as a method having a relatively low suction resistance with respect to the particle sizer. However, what has been adopted in the past is a tangential inflow type and a cyclone system with a reversing outflow direction, which is difficult to process in a complicated three-dimensional shape and becomes a relatively large device, so securing the installation space, etc. May be a problem. In addition, if the suction is performed at a large flow rate, the sizing performance is remarkably deteriorated, so that it has been necessary to sample for a long time at a low suction flow rate.

As a comparatively small cyclone type, a straight type cyclone type is known. Since this straight traveling type cyclone is easy to miniaturize, there are advantages such as few restrictions on the mounting position. Non-Patent Document 1 is a study of adopting this straight-traveling cyclone as an air dust sizing device.
In this non-patent document 1, a sizing apparatus for separating inhalable dust using a high flow rate air sampler is proposed. However, the separation accuracy with respect to inhalable dust, PM2.5, etc. was not sufficient.

Utility model registration No. 3158839

Toshihiko Meisei et al., “Prototype of a sizing device for high volume air sampler using axial flow cyclone”, 53rd Japan Occupational Health Engineering Society, November 13, 2013

  An object of the present invention is to provide a sizing / collecting device that can be downsized as compared with a conventional cyclone sizing device and that has sufficient separation performance even when sucked at a high flow rate. It is to provide a sizing unit.

  As a result of intensive studies to solve the above problems, the present inventor has found that the following inventions meet the above object, and have reached the present invention. That is, the present invention relates to the following inventions.

  The present invention is a rectilinear cyclone type sizing unit that is attached to the upstream side of the suction device and sizing dust in the air sucked by the suction device, and is sucked by the suction device and flows as a swirling flow Both ends are opened so that the air that has flowed into the outer cylinder of the sizing unit is provided coaxially with the outer cylinder inside the outer cylinder and the outer cylinder, and flows into the outer cylinder of the sizing unit. The present invention relates to a sizing unit comprising an inner cylinder, the inner cylinder having a frustoconical portion on the inflow side of the inner cylinder having a return plate facing the outflow direction of the outer cylinder. By using the sizing unit having such a configuration, sizing having sufficient separation performance can be performed even if suction is performed at a high flow rate. In the present invention, the inflow direction as the entire large flow corresponding to the inlet side of the sizing unit is simply referred to as the inflow direction, and the outflow direction as the entire large flow corresponding to the suction unit side for the sizing unit is simply referred to as the outflow direction. Sometimes called direction. The outflow direction of the sizing unit may be referred to as the downward direction of the sizing unit, and the inflow direction, which is the opposite side, may be referred to as the upward direction of the sizing unit. When using this sizing unit, the suction direction of the suction device may be set to the horizontal direction, and the sizing unit may also be used with the inflow-outflow direction as the horizontal direction.

  The present invention relates to a rectilinear cyclone type sizing unit that is attached to the upstream side of a suction device and sizing dust in the air sucked by the suction device. The sizing unit of the present invention classifies the dust in the air sucked by the suction device. Various natural environments, such as smoke generated dust, dust generated at soil particles, factories, construction sites, etc., and the working environment include dust (air dust) also called particulate matter suspended in the air May be. Since these dusts may be harmful to the human body, it is required to measure their concentrations. In particular, since the harmfulness when inhaled by the human body varies greatly depending on the size of the particles, sizing and collecting to measure the dust concentration of a specific size (for example, inhalable dust) However, the apparatus using the sizing unit of the present invention can be used for sizing air dust in various environments and places.

  The sizing device to which the sizing unit of the present invention is attached sucks air, and collects dust of a predetermined size sized by the sizing unit in the filter after passing through the sizing unit. be able to. In addition, a cyclone method is used as a sizing method of this sizing unit. The cyclone system has a structure in which large and small particles are separated by utilizing the fact that large particles are biased outward and small particles are biased inward by the centrifugal force of the swirling flow generated in the sizing unit. As the structure of the cyclone system, the outflow direction of the cyclone system generated in the sizing unit of the present invention is a straight-ahead type in which the collected dust (collected dust) and the clean fluid flow out in the same direction. The rectilinear cyclone system can achieve a cyclone for performing the separation with a relatively small structure.

  The present invention is characterized by the structure of the sizing unit. The sizing and collecting device to which the sizing unit of the present invention is attached collects dust suspended in the air when the air is sucked into the filter, and the sucked air amount and the filter before and after the collecting. It is suitable for the filter weighing method for obtaining the dust concentration from the change in weight. A sizing unit is attached to the sizing / collecting device so that the size of the dust reaching the filter is selectively sized so as to have a predetermined size. In addition, when the sizing device sucks air, it passes through the structure of this sizing unit to generate a swirling airflow, and the centrifugal force generated by this swirling flow and the shape of the sizing unit described later Achieves excellent sizing effect.

  The sizing unit of the present invention has an outer cylinder through which air sucked by a suction device and introduced as a swirling flow flows. In order to allow the swirl flow to flow into the outer cylinder, an inlet that sucks air and a guide that uses the air sucked from the inlet as a swirl flow are provided. First, the sizing unit is provided with an inlet for allowing the air to be sampled to flow in. Further, a guide is provided for turning the air sucked by the suction device and introduced from the inlet into a swirling flow so that the air flows in the outer cylinder of the sizing unit. The guide for making this swirl flow can employ various structures employed in a straight-forward cyclone system or the like. The inflow direction may be either a tangential inflow type that flows in from a direction perpendicular to the axis of the sizing unit main body or an axial flow type that flows in from a direction parallel to the axis of the separator main body. What is necessary is just to be made to flow in as a swirl flow.

  More specifically, as a guide for making a swirl flow, for example, a spiral groove provided on the wall of the outer cylinder centering on the upper part close to the inlet, or a tangential inflow type is often used. A structure in which a plurality of pipes are provided along the wall of the outer cylinder so as to guide the swirling flow immediately after inflow, and suction is performed at the center of the outer cylinder so that the swirling flow is easily maintained. Examples include a structure in which an in-cylinder guide having a conical tip in the apparatus direction and a cylindrical columnar portion is provided. Among these, what employ | adopts the principle of what is called a tangential inflow type so that it may have an inflow guide which flows into the outer cylinder the swirling flow by the pipe | tube perpendicular to the axis | shaft of the said outer cylinder is preferable. When a swirling flow is generated by such an inflow method, the size of the entire sizing unit can be easily reduced, and the configuration is also suitable for sizing by the sizing unit of the present invention.

  The sizing unit of the present invention has an in-cylinder guide having a conical tip and a cylindrical body, the in-cylinder guide is coaxial with the inner cylinder, and the conical tip. Is preferably provided in the outflow direction, and is disposed so as to create a gap between the in-cylinder guide and the truncated cone portion of the inner cylinder. As described above in part, by providing such an in-cylinder guide, the air that has been sucked into the sizing unit and turned into a swirling flow is less likely to be swirled at the upper part of the inner tube. Large particles are likely to settle to the dust pot in between. That is, such an in-cylinder guide greatly contributes to maintaining the swirling flow in the outer cylinder, and is suitable as a guide for the sizing unit of the present invention that is downsized and used for operation at a large flow rate. Of structure.

  The sizing unit of the present invention is provided with an outer cylinder in which air sucked by a suction device and flowing in as a swirling flow flows, and is provided inside the outer cylinder and coaxially with the outer cylinder, and the outer cylinder of the sizing unit And an inner cylinder that is open at both ends so that air that has flowed into the suction apparatus flows into the suction device. The large-diameter particles gathered to the outside by the swirl flow pass through the gap between the outer cylinder and the inner cylinder, and are settled and stored in the bottom portion corresponding to the outflow direction of the outer cylinder and forming a gap with the inner cylinder. The The portion where the large particle size is stored is also called a capturing portion (dust pot). Large particles in the air sucked as a swirling flow in the outer cylinder are separated so as to be biased to the outside in a direction close to the inner wall of the outer cylinder, and small particles are biased to the inside. The large particles settle into the dust pot along the inner wall of the outer cylinder. On the other hand, in a mixture of small particles and air (sometimes called clean air because large particles are removed), both ends provided coaxially with the outer cylinder inside the outer cylinder are open. It passes through the inner cylinder and flows out toward the suction device.

  In the sizing unit of the present invention, the inner cylinder is an inner cylinder having a frustoconical portion having a return plate facing the outflow direction of the outer cylinder on the inflow side of the inner cylinder. A clean fluid containing dust of a small particle size is selectively supplied to the inner cylinder by a truncated cone-shaped part provided on the inflow side (upper part) of the inner cylinder and having a return plate facing the outflow direction (bottom part) of the outer cylinder. And flows out to the suction device side. In providing the truncated cone portion having the return plate in the inflow direction of the inner cylinder, first, the flow of dust in the sizing unit is as follows. First, depending on the size of the dust in the air sucked as a swirling flow, large particles are stored in dust spots in the gap between the outer cylinder and the inner cylinder, and small particles pass through the inner cylinder. Out of the sizing unit. At this time, the particles entering the dust pot generate an ascending airflow that flows into the inner cylinder side while the swirling airflow is partially eliminated by the swirling airflow that continues to flow into the dustpot side during operation of the sizing and collecting device. There arises a problem that a part of large-diameter particles pass through the inner cylinder and flow out of the sizing unit due to the air flow. Here, the present invention has found that by providing a truncated cone portion having a return plate with respect to the dust pot direction at the upper part of the inner cylinder, there is an effect of remarkably preventing the outflow of large particles due to the rising airflow. It is based on. This is because the flow that sinks in the dust pot direction is caused by the frustoconical portion provided at the upper part of the inner cylinder and the return plate that is further provided in the frustoconical part in the direction of the dust pot (outer cylinder bottom direction). It is considered that the particles having a size that is generated and stored in the dust pot are preferentially settled because they are greatly affected by the sinking flow. In this way, when the large particles settle in the dust pot, the small particle size dust passes through the inner cylinder more selectively and is appropriately collected by the filter provided on the downstream side of the sizing unit. The

  In the sizing unit of the present invention, it is preferable that the return plate has a width from 5 mm to 15 mm starting from the inflow direction end of the truncated cone portion and extending to the outflow direction end. This return plate has a certain width from the inflow direction end corresponding to the upper end of the truncated cone portion to the outflow direction end corresponding to the lower direction, so that the return plate faces downward between the return plate and the inverted conical top (the bottom of the outer cylinder). A recess is formed on the outflow side. In other words, the depth of the groove for generating a flow that sinks toward the dust pot can be adjusted by the width of the return plate. In addition, it is preferable that the depth of the groove part produced between a return plate and a truncated cone-shaped part is 2 mm or more by adjusting the width | variety of a return plate in this way. Moreover, it is preferable that the depth of a groove | channel shall be 12 mm or less from relationship with the width | variety of a preferable return plate. This groove part is calculated | required by the distance from the outflow direction end of a return plate to a groove part. When an upward air flow from the bottom of the outer cylinder hits the concave portion, a downward air flow is generated. Due to the influence of the downward air flow and the collision with the concave portion, the particles having a large particle size settle again on the dust pot side. At this time, the groove portion of the recess becomes deeper as the width of the return plate increases. If the width of the return plate is too large, the swirling flow in the sizing unit does not easily pass between the inner cylinder and the outer cylinder, the swirling flow is eliminated at the upper part of the inner cylinder, and large particles that should settle in the dust pot. May not gather on the outer cylinder wall side and pass through the inner cylinder as it is. On the other hand, when the width | variety of a return plate is too small, it may become difficult to produce the force which makes a big particle settle in a dust pot direction. From such a viewpoint, the width of the return plate is preferably in the range as described above.

  The present invention can provide a sizing apparatus characterized in that the above-described sizing unit is attached to a suction port of a suction device via a filter. This sizing unit is attached to the suction device and sizing the air sucked by the suction device. As a suction device to which this sizing unit is attached, for example, a device having an air pump for sucking air can be used, and a suction flow rate, a suction time, a total suction amount, etc. can be set as appropriate. A suction device having a function of measuring can be used. In addition, when used as a sizing / collecting device, a filter is generally attached just before the suction port on the upstream side of the suction device, and used to collect particles having a small particle size that are sized by the filter. . As the filter, a filter conforming to a standard for collecting the atmospheric dust to be measured is used. Examples of these suction devices include a suction device of a conventional impactor type sizing device. More specifically, a high volume air sampler (manufactured by Shibata Kagaku) may be mentioned as a device having a suction function. Moreover, as a filter, the glass fiber filter with a fluororesin (for example, Teflon (trademark)) binder which has no hygroscopic property and is generally used for the measurement of particle concentration in the environment can be used.

  The collection and sizing apparatus of the present invention employs the sizing unit having the above-described configuration as the sizing unit. According to this sizing unit, the suction flow rate of 200 L / min to 1500 L / min is large although it varies depending on the specific position of the sizing unit and its internal structure, their size, and the particle size to be sized. Even under conditions, excellent sizing accuracy (separation accuracy) can be achieved. Since such a suction flow rate can be obtained, a sufficient amount of sampling can be performed in a short time. When the suction flow rate is outside the range suitable for the structure of the sizing unit, the sizing accuracy may be lowered. In particular, when operating with a large flow rate, it is preferable to increase the diameter of the outer cylinder and the inner cylinder so that a large centrifugal force is easily applied.

  The size of the particle size to be sized varies depending on the specific position of the sizing unit, the size thereof, etc., as described above in part. For example, if you want to set the separation accuracy on the larger particle side, increase the size of the outer cylinder (especially its diameter), and increase the size of the in-cylinder guide (especially its diameter). The gap between the part and the outer cylinder is not greatly changed. Alternatively, by reducing the suction flow rate, for example, from 50 L / min to 400 L / min, the 50% separation diameter can be adjusted to the larger particle side, such as 2 μm to 2.5 μm. On the other hand, when setting the separation accuracy to the smaller particle side, the distance (radius) from the center line corresponding to the axis of the outer cylinder and the inner cylinder to the guide of the cylinder, the inner cylinder, and the outer cylinder is shortened. , 50% separation diameter can be adjusted to smaller particles. Note that if the suction flow rate is extremely lowered, the swirling flow becomes weak and the cyclone may not be separated as a cyclone. Therefore, it is basically preferable to perform adjustment according to the size of each component of the sizing unit.

  This invention can be set as the method of measuring the air dust density | concentration by measuring the inhalable air dust collected by the particle size collection device. The airborne dust that is sized and collected using the sizing device of the present invention is sized and collected at a specific size of the airborne dust that passes through the sizing unit. By being sized and collected at this specific size, a separation curve having a specific particle size distribution can be obtained. That is, it is possible to sample only air dust having a specific size by collecting the particles using the particle collection device of the present invention. Using this sampling characteristic, for example, it is designed to selectively pass inhalable airborne dust, measure the filter weighing type with the above filter attached, and convert it by a predetermined sampling air amount. It can be a method for measuring the concentration of airborne dust. As described above, the divided collection device of the present invention has sufficient separation accuracy even at a relatively high suction flow rate. For this reason, when it employ | adopts as the measuring method of an air dust density | concentration, it has the advantage that an air dust density | concentration can be measured in a short time.

  According to the rectilinear cyclone type sizing unit of the present invention, although a cyclone method is adopted, a sizing apparatus that can be achieved in a small size and has sufficient separation performance even when sucked at a high flow rate is obtained. be able to.

It is a figure which shows the schematic of the particle size collection apparatus of this invention. It is a figure which shows the schematic of the sizing unit of the sizing apparatus of this invention. It is a figure which shows the elements on larger scale of the sizing unit of the sizing apparatus of this invention. It is a figure which shows an example of the structure of the guide for setting it as a swirl | vortex flow in the sizing unit of this invention. It is a figure which shows the result of having measured the particle diameter divided using the particle size collection device of the present invention. It is the figure which performed the comparison with the particle diameter divided using the particle size collection apparatus of this invention, and the ideal separation curve of PM2.5. It is the figure which compared the result of having measured the PM2.5 density | concentration in air | atmosphere using the particle size collection apparatus of this invention, and the result measured by the conventional method.

  The embodiment of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of the embodiment of the present invention, and the present invention has the following contents unless the gist thereof is changed. It is not limited to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway front view showing an outline of the particle collection device of the present invention. FIG. 2 is an enlarged view of the sizing unit of the sizing and collecting apparatus shown in FIG. FIG. 3 is a partial enlarged view for explaining in more detail the structures of the inner cylinder, the outer cylinder, and the in-cylinder guide in the sizing unit shown in FIG. FIG. 4 is a diagram illustrating an example of the configuration of the inlet and the guide when the sizing unit of the sizing and collecting apparatus shown in FIG. 1 is observed from the left side.

  Based on these FIGS. 1 to 4, the sizing unit and the sizing collector will be described in more detail. In the separation / collection device 100 shown in FIG. 1, the sizing unit 10 is attached in front of the filter 8 provided in front of the suction device 20 of the sizing / collecting device 100. The sizing unit 10 includes an inlet 1 into which air sucked by the suction device 20 flows, an inflow guide 2a (see FIG. 4) and an in-cylinder guide 2b in which the air that has flowed in from the inlet 1 is swirled. It has an outer cylinder 3 through which air sucked as a swirling flow flows. Furthermore, it has the inner cylinder 4 which is provided coaxially with the outer cylinder 3 and whose both ends are opened so that the air sucked into the sizing unit 10 flows into the suction device 20. Here, a space formed by the bottom 31 of the outer cylinder 3 and the gap d3 between the outer cylinder 3 and the inner cylinder 4 becomes a dust pot 7 (see FIGS. 2 and 3). The large-diameter particles pass through the gap d2 (see FIG. 3) between the outer cylinder 3 and the return plate 6 and are stored in the dust pot 7 (see FIGS. 2 and 3). A frustoconical part 5 having a return plate 6 facing the outflow direction (bottom part direction) of the outer cylinder is provided in the upper part corresponding to the inflow direction of the inner cylinder 4. The particles are selectively passed through the inner cylinder 4 and flow toward the suction device 20, and small particles in the clean fluid are collected by the filter 8.

  The suction device 20 is a suction device that can control the suction flow rate, and is provided with a control unit for controlling the suction flow rate, a monitor for managing the suction flow rate, and the like. Dust contained in the air sucked by the suction device 20 is collected by the filter 8 provided in front of the suction device 20. In order to control the particle size distribution of the dust collected by the filter 8, a sizing unit 10 is attached on the upstream side of the filter.

  The sizing unit 10 is configured to store dust larger than a specific particle size in a dust pot and to classify the dust by a structure that allows dust smaller than the specific particle size to pass through. In order to perform this sizing, the sizing unit of the present invention adopts a straight-forward cyclone system. The rectilinear cyclone system contributes to the miniaturization of the entire sizing / collecting device because it is easy to miniaturize. Further, since the straight traveling type cyclone system is achieved by the structure of the sizing unit, it can be attached to a conventional suction device.

  An example of a specific method for generating a swirling flow for performing this sizing will be described with reference to FIGS. First, the sizing unit 10 has an inlet 1 for sucking air, and a guide for turning the air sucked from the inlet 1 into a swirling flow is provided. The structure of the inflow port and the guide is as shown in FIG. 4. Immediately after the inflow, the circular inflow port and the inflowed air flow as a swirl flow through the outer cylinder 3 of the sizing unit. The inflow guide 2a provided in the cylinder and the in-cylinder guide 2b for stabilizing the swirling flow in the outer cylinder are used. The inflow guide 2a is a pipe that is guided in such a direction that the air introduced from the inflow port turns counterclockwise as indicated by an arrow in FIG.

  The air sucked as the swirl flow by the inflow guides 2a respectively provided at the four inlets 1 flows in the outer cylinder 3, but at this time, the swirl flow is easily maintained along the circumference of the outer cylinder. An in-cylinder guide 2b is provided near the center of the outer cylinder on the same axis. This in-cylinder guide 2 b makes it difficult for the swirling flow to be eliminated at the upper part of the inner cylinder 4, and makes it easier for large particles to settle in the dust pot 7. It arrange | positions so that a clearance gap may arise between the said cylinder guide 2b and the truncated cone-shaped part 5 of the inner cylinder 4, and the cylinder guide 2b arises between the inner cylinders 4 by adjusting the height. The height can be adjusted by inserting a screw into the in-cylinder guide height adjusting mechanism 2c and fixing the position of the in-cylinder guide 2b so that the gap can be adjusted.

  FIG. 3 is a partially enlarged view of the sizing unit 10. Although partly described above, as shown in FIG. 3, the sizing unit 10 in this embodiment is characterized by the inner cylinder 4 provided with the truncated cone portion 5 having the return plate 6, and the outer cylinder 3 and the in-cylinder guide. Large particles and clean particles pass through the gap formed between 2b. The return plate 6 is a plate having a width L1 from the inflow direction end 62 to the outflow direction end 63 of the return plate 6. A groove 61 is formed between the return plate 6 and the truncated cone portion 5. The groove portion can use the depth L2 as an index at the time of design.

  In the outer cylinder 3 through which air sucked as a swirling flow by the inflow guide 2a and the in-cylinder guide 2b flows, large particles are separated to the outside and small particles and clean air are separated to the inside by the swirling flow. Due to this separation, large particles pass through the gap d2 between the return plate 6 of the inner cylinder and the outer cylinder 3, and are stored in the dust pot 7. Further, the inner cylinder 4 provided coaxially with the outer cylinder 3 and open at both ends so that the air sucked into the sizing unit 10 flows to the suction device 20 and the filter 8 side of the sizing collector 100. The cleaning fluid flows to the suction device (and filter) side through a gap d1 that is the shortest distance between the inflow direction end 62 of the return plate 6 corresponding to the upper end of the inner cylinder 4 and the in-cylinder guide 2b.

  Here, the large-diameter particles separated by the swirling flow and trapped so as to be stored in the dust pot 7 are partially sucked by the rising airflow from the bottom part while continuously sucking. In some cases, the particles may pass through and flow out, and the passage of the large-diameter particles causes a reduction in the separation accuracy of the sizing unit. In order to prevent the outflow of the large-diameter particles, the upper part corresponding to the inflow direction of the inner cylinder 4 of the sizing unit 10 of the present invention is directed to the outflow direction of the outer cylinder 3 (the direction of the bottom 31 (dust pot 7)). A frustoconical part 5 having a return plate 6 is provided. As a result, the large particle size dust is less likely to flow out in the outflow direction through the inner plate 4 by the return plate 6, and the small particle size dust selectively passes through the inner tube 4 so that an excellent sizing effect is achieved. Indicates. As described above, the design of the gap d2, the gap d1, the width L1 of the return plate 6, and the depth L2 of the groove 61 also maintains the swirl flow in the sizing unit and the outflow of large-sized particles from the dust pot. Prevention is affected, and by adjusting these designs, the separation efficiency and separation accuracy of the sizing unit can be adjusted. If the suction flow rate per unit time can be set high, a large amount of air can be sampled in a short time, so that the air dust concentration can be measured in a short time.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is changed.

[Device configuration]
・ Sizing unit (1)
A sizing / collecting device was manufactured using the sizing unit (1) having the structure shown in FIGS. The main structure of the sizing unit (1) manufactured at this time is shown below. The outer cylinder 3 had a diameter of 90 mm and a height of 74 mm. Further, the diameter of the cylindrical part of the inner cylinder 4 is 60 mm, the height is 25 mm, the truncated cone part provided at the upper part of the inner cylinder is 30 mm in height, and the maximum diameter is 80 mm. A return plate having a width of 10 mm was provided at the part. Thereby, the groove part of a truncated cone-shaped part and a return plate becomes the shape which goes to an outer cylinder bottom part (dust pot) direction. In addition, each of the four inlets is provided with an inflow guide on the pipe that immediately turns into a counterclockwise swirling flow when the lid provided with the inlet is viewed from the front, and further functions as an in-cylinder guide. A lid was attached to the outer cylinder to constitute a sizing unit. In this sizing unit (1), the gap d1 between the in-cylinder guide 2b and the truncated cone portion 5 is 10 mm, the gap d2 between the return plate 6 and the outer cylinder 3 is 5 mm, and the width L1 of the return plate 6 is The depth L2 of the groove 61 formed between the return plate 6 and the truncated cone portion 5 was 3 mm. This sizing unit exhibits particularly excellent separation accuracy when operated at a suction flow rate of 400 to 600 L / min.
・ Sizing unit (2)
The sizing unit (1) having a structure excluding the return plate was produced, and sizing was performed. (Reference: Non-Patent Document 1)
-Suction device "High volume air sampler-HV-500F type" manufactured by Shibata Kagaku Co., Ltd. was used. The conventional sizing unit portion attached to this apparatus was removed, and the sizing unit (1) or (2) described above was attached.
Filter “T60A20” manufactured by Tokyo Dailek Co., Ltd. (110 mm type Teflon (registered trademark) binder glass fiber filter)

[Example 1, Comparative Example 1]
Tests of Example 1 using the sizing unit (1) used in the present invention and the Comparative Example 1 using the sizing unit (2) having no return plate using the contamination model gas are as follows. went. The gas (contamination model gas) containing particles produced by coagulating toner powder in a dust chamber using a fluidized bed type dust generator is measured before and after the sizing unit of the present invention to improve the separation efficiency. It was measured. As an operating condition of the suction device, the suction flow rate was set to 500 L / min.
In measuring the separation efficiency, the sample before the sizing unit was provided with a sample port before the inlet and the sample was extracted to measure the concentration for each particle size. Further, the sample after the sizing unit was provided with a pipe having a sufficiently long sampling port between the inner cylinder and the filter, and the sample was extracted from the sampling port, and the concentration for each particle size was measured. The concentration for each particle size was measured using an electronic low-pressure impactor (DEKATI "ELPI").
The measurement results of the separation efficiency of Example 1 and Comparative Example 1 are shown in FIG.
As is clear from FIG. 5, the sizing unit (1) of the present invention provided with the return plate has a sharper separation accuracy than the sizing unit (2), and is particularly excellent when the particle size is 3 μm or more. The separation efficiency was shown.

[Example 2]
In order to investigate more detailed classification characteristics of the sizing unit (1), the following 7 types of standard latex particles (7 types of particle sizes of about 1, 2, 2.5, 3, 4, 5, 7) were used. And tested.
Standard latex particles “STANDEX” manufactured by JSR Life Science Co., Ltd .: 1.005 μm (± 0.021 μm), 2.005 μm (± 0.021 μm)
“DYNOSHERES” manufactured by JSR Life Sciences Co., Ltd .: 3.21 μm (± 0.072 μm), 5.125 μm (± 0.115 μm), 7.123 μm (± 0.16 μm)
“Duke” manufactured by Thermo Fisher Scientific Co., Ltd .: 2.504 μm (± 0.027 μm), 4.000 μm (± 0.027 μm)

[Test operation using standard latex particles]
A model gas containing a mixture of the standard latex particles was prepared, and Example 2 was performed using the sizing unit (1) used in the present invention. Clean air is sent from the air purifier to the nebulizer, the standard latex particles installed in the nebulizer are atomized, and the gas containing the standard latex particles (model gas) is a suction device equipped with a sizing unit (1). Aspirated. At this time, the particle concentration was measured before and after the sizing unit, and the separation efficiency was measured. As an operating condition of the suction device, the suction flow rate was set to 400 L / min.
In measuring the separation efficiency, the sample before the sizing unit was provided with a sample port before the inlet and the sample was extracted to measure the concentration for each particle size. Further, the sample after the sizing unit was provided with a pipe having a sufficiently long sampling port between the inner cylinder and the filter, and the sample was extracted from the sampling port, and the concentration for each particle size was measured. The concentration for each particle size was measured using a particle counter (“KC52” manufactured by Rion).
FIG. 6 shows the result of performing a PM2.5 classification characteristic test using standard latex particles according to Example 2 and enlarging the vicinity of the 50% diameter. In FIG. 6, the line indicated by a broken line is an ideal separation curve of PM2.5. Moreover, the separation accuracy when the particles are collected using this particle size unit (1) has a 50% separation diameter of 2.5 μm and is suitable for PM2.5 particle collection. .

[Example 3]
[Atmospheric measurement]
The PM2.5 concentration in the atmosphere was measured using the particle collection device of the present invention. The filter and the sizing unit (1) were attached to the suction device, the suction flow rate of the suction device was 500 L / min, and the PM2.5 concentration was measured from the change in weight of the filter before and after suction for 1 hour.
In order to compare with the conventional measuring method, the value measured using BAM (particle concentration measuring device by β ray attenuation) was obtained and compared with the measurement result by the particle size collector of the present invention.
Evaluation results by conventional BAM (horizontal axis: ““ BAM (μg / m ³ ) ”) and measurement results by filter weighing method using a sizing device using the sizing unit of the present invention (vertical axis: FIG. 7 shows a graph comparing “Cyclone HV (μg / m ³ )”). As is clear from FIG. 7, the result of measuring the PM2.5 concentration using the sizing / collecting device of the present invention showed a high correlation with the conventional method.

  According to the sizing / collecting apparatus using the sizing unit of the present invention, it is possible to use the sizing / collecting of particles in the atmosphere, which is useful for measuring the concentration of air dust.

DESCRIPTION OF SYMBOLS 1 Inflow port 2a Inflow guide 2b In-cylinder guide 2c In-cylinder guide height adjustment mechanism 3 Outer cylinder 31 Bottom part of outer cylinder 4 Inner cylinder 5 Frustum-shaped part 6 Return plate 61 Groove part 62 Inflow direction end 63 Outflow direction end 7 Dust pot 8 Filter 10 Sizing unit 20 Suction device 100 Sizing device

Claims (6)

A linear cyclone type sizing unit attached to the upstream side of the suction device and sizing dust in the air sucked by the suction device,
An outer cylinder through which air sucked by the suction device flows and flows as a swirling flow;
Inside the outer cylinder, it is provided coaxially with the outer cylinder, and has an inner cylinder open at both ends so that the air that has flowed into the outer cylinder of the sizing unit flows into the suction device,
The sizing unit, wherein the inner cylinder has a frustoconical part having a return plate facing the outflow direction of the outer cylinder on the inflow side of the inner cylinder.   The sizing unit has an in-cylinder guide having a conical tip and a cylindrical body, the in-cylinder guide is coaxial with the inner cylinder, and the conical tip is directed in the outflow direction. 2. The sizing unit according to claim 1, wherein the sizing unit is provided so as to form a gap between the in-cylinder guide and the truncated cone portion of the inner cylinder.   3. The sizing unit according to claim 1, wherein the return plate has a width from 5 mm to 15 mm starting from the inflow direction end of the truncated cone portion and extending to the outflow direction end.   The sizing unit according to any one of claims 1 to 3, further comprising an inflow guide for allowing a swirling flow by a pipe perpendicular to the axis of the outer cylinder to flow into the outer cylinder.   A sizing / collecting device, wherein the sizing unit according to any one of claims 1 to 4 is attached to a suction port of a suction device via a filter.   A method for measuring an airborne dust concentration by measuring inhalable airborne dust collected and collected by the particle collecting apparatus according to claim 5.