JP2018124214A - Single standard particle aerosol generator and generating method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method thereof capable of continuously generating a single standard particle aerosol over a long period of time.SOLUTION: A single standard particle aerosol generator 100 is provided, which includes: an ink jet head 42 for generating an aerosol by continuously ejecting fluid dropping which is the standard particle dispersion for causing non-melting standard particles to be dispersed in solvent higher in viscosity than water into an air flow inside a pipe-body 12 from a stored vial 32; a first heating part 50 for causing the solvent to be evaporated by heating the aerosol provided in the downstream side; a solvent evaporation collecting part 60 for collecting the evaporation of the solvent in the aerosol provided in the downstream side; and a second heating part 70 for generating the aerosol of the standard particles by heating the aerosol provided in the downstream side.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an apparatus and method for aerosolizing fine particles, and more particularly to an apparatus and method for aerosolizing standard particles, which are fine particles having a known particle diameter.

  In recent years, in the field of air pollution, PM10 suspended particulate matter having a particle size of 10 μm or less and PM2.5 aerosol particles having a particle size of 2.5 μm or less, which are stipulated in environmental standards, have been measured. In various phenomena such as light scattering, transport and deposition related to aerosol particles in the atmosphere, the particle size is one of the most influential parameters, and measurement of the particle size distribution is essential. This measuring instrument includes particle size distribution measurement of light scattering airborne particle counter (OPC), scanning electric mobility spectrometer (SEMS), aerodynamic diameter spectrometer (APS), cascade impactor (hereinafter referred to as impactor), etc. The device is in use.

  In such measurement, it is important to grasp a trend over a long period of time, and it is necessary to perform calibration for maintaining the above-described particle size distribution measuring apparatus with a predetermined performance. For the calibration of the response of the apparatus described above, polystyrene latex spheres or the like which are standard particle diameters are used.

  On the other hand, there is almost no calibration with respect to the particle number concentration which is the vertical axis of the measured particle size distribution. Since this calibration is performed in a laboratory environment, it is necessary to transport the measuring instrument to be calibrated to the laboratory. This cannot maintain the continuity of the observation data and reduces the motivation for calibration.

  Therefore, the inventor's group has developed an aerosol generator described in Non-Patent Documents 1 and 2. This aerosol generator uses a solvent such as water or isopropyl alcohol to create a solution by adding soluble solutes to these solvents, and continuously discharges the solution as droplets from the inkjet head at a certain frequency. Then, aerosols are generated by causing standard particles of a solute component, which is a residue obtained by drying droplets, to accompany a clean air stream. This aerosol generator can be easily moved, and the instrument can be calibrated by transporting it to the observation site where the instrument is installed. In addition, an aerosol containing these standard particles can be generated by ejecting a liquid obtained by dispersing commercially available standard particles having a known particle size in water or the like from this aerosol generator with water. .

Iida, 3 others "Aerosol Research", Japan Society for Aerosol Science, 2012, Vol. 27, No. 4, p.341-349 Iida, K. et al., “Inkjet Aerosol Generator as Monodisperse Particle Number Standard”, Aerosol Science and Technology 2014, Vol. 48, No. 8, p. 789-802

  However, as the standard particle size increases, the mass of the particle increases, and gravity tends to affect the behavior of the standard particle in the dispersion, and in a flow path such as a pipe for supplying the solution or a liquid reservoir before discharging. Standard particles are likely to settle or float. When the standard particles settle or float, it becomes difficult to make these aerosols, so that it is difficult to continue transporting the standard particles at a stable concentration over a long period of time to the aerosol measuring device to be evaluated.

  Accordingly, one of the objects of the present invention is to provide an apparatus and method for aerosolizing standard particles continuously over a long period of time.

  According to one aspect of the present invention, there is provided an apparatus capable of generating an aerosol of a single standard particle, wherein a solution in which the standard particle not dissolved in the solvent is dispersed in a solvent having a viscosity higher than that of water. A droplet discharge unit that continuously discharges droplets in the air stream and generates an aerosol, and a first heating unit that is provided downstream of the droplet discharge unit and heats the aerosol to evaporate the solvent And provided downstream of the first heating unit, for collecting the vapor of the solvent in the aerosol, and downstream of the solvent vapor collection unit, and heating the aerosol. And a second heating unit that generates an aerosol of the standard particles.

  According to the above aspect, since the standard particles are dispersed in a solvent having a viscosity higher than that of water, the standard particles are present in the flow path until the solution is supplied to the droplet discharge unit and discharged. Sedimentation or floating can be prevented, and droplets containing a single standard particle (single particle standard particle) can be ejected. At the same time, the solvent vapor evaporated in the first heating unit is collected in the solvent vapor collecting unit provided downstream, so that the concentration of the solvent vapor in the airflow is reduced, and the standard particles in the aerosol It is possible to suppress the vapor of the solvent from adhering due to nuclear condensation or the like. Furthermore, by heating the aerosol in the second heating section, it is possible to evaporate and remove the solvent adhering to the standard particles, thereby generating a single standard particle aerosol.

  According to another aspect of the present invention, there is provided a method capable of generating an aerosol of single standard particles, in which a solution in which the standard particles not dissolved in the solvent is dispersed in a solvent having a viscosity higher than that of water. Supplying to the droplet discharge unit, the droplet discharge unit continuously discharging droplets into the air flow in the tube to generate aerosol, and heating the generated aerosol to evaporate the solvent Collecting the solvent vapor in the aerosol from which the solvent has been evaporated; and heating the aerosol from which the solvent vapor has been collected to generate an aerosol of the standard particles. Including such a method.

  According to the above aspect, since the standard particles are dispersed in a solvent having a viscosity higher than that of water, the standard particles are present in the flow path until the solution is supplied to the droplet discharge unit and discharged. It is possible to prevent sedimentation or levitation and the like, and it is possible to discharge a droplet containing a single standard particle (single particle standard particle). At the same time, the vapor of the solvent evaporated by heating the generated aerosol is collected, so the concentration of the solvent vapor in the airflow decreases, and the vapor of the solvent adheres to the standard particles in the aerosol by nuclear condensation etc. It is possible to suppress this. Furthermore, by heating the aerosol, it is possible to evaporate and remove the solvent adhering to the standard particles, thereby generating an aerosol of standard particles.

It is a block diagram which shows the structure of the single standard particle aerosol generator which concerns on one Embodiment of this invention. It is explanatory drawing of the principle of one Embodiment of this invention. It is the schematic which shows the structure of the single standard particle aerosol generator which concerns on one Embodiment of this invention. It is a figure showing an example of a solvent vapor collection part of a single standard particle aerosol generator concerning one embodiment of the present invention. It is a figure which shows the other example of the solvent vapor collection part of the single standard particle aerosol generator which concerns on one Embodiment of this invention. It is a figure which shows the other example of the solvent vapor collection part of the single standard particle aerosol generator which concerns on one Embodiment of this invention. It is a flowchart which shows the generation method of the aerosol of the standard particle which concerns on one Embodiment of this invention. It is a graph which shows the particle production frequency of the polystyrene latex sphere in the aerosol of the Example which concerns on this invention, and a comparative example. It is a graph which shows the particle size distribution of the polystyrene latex sphere in the aerosol of the Example which concerns on this invention.

  One of the techniques disclosed in the present specification, claims and drawings is known mainly for use in testing, in which the particle size is known, such as polystyrene latex spheres (hereinafter also referred to as “PSL spheres”). It relates to a technique for dispersing standard particles to be dispersed in the air. For the sake of simplicity, the description will be made using PSL spheres unless otherwise specified, but the present invention is not limited thereto. In addition, the term “aerosol” used in the present specification, claims, and drawings refers to a liquid or a solid, or a plurality of fine particles containing a liquid and a solid in a gas and a gas in a state of being suspended in the gas. Includes floating particles or groups.

  Methods for aerosolizing PSL spheres are mainly classified into wet and dry methods. A typical example of wet aerosolization is a nebulizer, in which test particles are dispersed in water and sprayed under pressure. The upper limit of the particle size range that the nebulizer can generate at a stable concentration is about 2 μm, whereas it is about 10 μm to 20 μm, which is the upper limit of the measured particle size range of aerosol measuring instruments for the micrometer particle size range. It is insufficient.

  Also, the efficiency with which the nebulizer can aerosolize the PSL spheres in the dispersion is usually as low as several percent, and this efficiency worsens as the particle size of the PSL spheres increases. This is due to the fact that PSL spheres are easily deposited on the pipe wall due to gravity and inertia during the process of transporting aerosolized PSL spheres in the pipe, and that the PSL spheres are gravity settled in the dispersion. it is conceivable that.

  On the other hand, in dry aerosolization, PSL spheres are rolled up in the air using brushes, vibrations, airflow, and the like. In this method, the generated concentration of PSL spheres in the aerosol tends to be intermittent with respect to time. It is not desirable in the evaluation of the aerosol measuring instrument that the particle number concentration in the aerosol used for the test is unsteady.

  Further, many PSL spheres rolled up by dry method are constituted by aggregation of a large number of PSL spheres. For this reason, turbulent flow or sound waves are applied to dislodge aggregates into single-particle PSL spheres, but this process is probabilistic and all aggregates are completely isolated in air. It is difficult to separate the particles into PSL spheres.

  Moreover, it is cost-effective as a practical viewpoint common to both wet and dry processes. Since dispersions and dry powders of PSL spheres are sold at a price per mass of PSL sphere components, the unit price per PSL sphere increases as the particle size increases. Therefore, as the particle size becomes about a few micrometers or larger, it becomes necessary to be more aware of the cost of the PSL spheres used to evaluate the aerosol meter.

  In the present specification and drawings, as one aspect of the embodiment according to the present invention, it is possible to avoid excessive consumption of expensive standard particles having a particle size of about 2 μm or more and to evaluate an aerosol measuring instrument. Provided are an apparatus and a method for generating standard particles capable of maintaining a sufficiently stable concentration over a necessary time.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a single standard particle aerosol generator according to an embodiment of the present invention.

  Referring to FIG. 1, a single standard particle aerosol generator 100 according to an embodiment of the present invention includes an apparatus main body 10, a gas supply unit 20 that supplies gas into the apparatus main body to generate an air flow, and an aerosol. A solution supply unit 30 for supplying a liquid (hereinafter also referred to as “standard particle dispersion”) in which standard particles insoluble in the solvent are dispersed in a solvent having a higher viscosity than water, which is a particle component of A droplet discharge unit 40 that generates an aerosol by discharging the standard particle dispersion into a gas stream, a first heating unit 50 that heats the aerosol and evaporates the solvent in the stream, and is heated. Solvent vapor collecting section 60 that collects the vapor of the solvent in the aerosol containing gas, second heating section 70 that generates aerosol of standard particles by heating the aerosol, and cooling or natural cooling of the aerosol of standard particles Cooling section It has 0, the control unit 90, a.

  FIG. 2 is an explanatory diagram of the principle of one embodiment of the present invention.

  Referring to FIG. 2 together with FIG. 1, in (a), a standard particle dispersion is prepared in which standard particles insoluble in this solvent are dispersed in a solvent having a higher viscosity than water.

  In (b), the standard particle dispersion is supplied to the nozzles of the inkjet head of the droplet discharge unit 40. The standard particle dispersion is supplied to the vicinity of the nozzle tip by the opening operation of the nozzle.

  In (c), a droplet of the standard particle dispersion is discharged from the nozzle by the closing operation of the nozzle, and the particulate matter is accompanied by the filtered airflow. The droplets may include standard particles and a solvent as illustrated, or may be a solvent alone (not illustrated).

  In (d), the aerosol is heated by the first heating unit 50 to evaporate the solvent of the droplets in the air stream. As a result, the solvent of the droplets is reduced or removed, and an aerosol containing standard particles in a dry state is generated, and at the same time, the concentration of the solvent vapor in the air stream is increased.

  In (e), the solvent vapor collecting unit 60 condenses the solvent vapor in the airflow on the tube wall surface, for example, by cooling the tube wall. This reduces the concentration of solvent vapor in the air stream. At the same time, it is conceivable that the solvent vapor condenses using the standard particles as nuclei.

  In (f), when the aerosol is heated by the second heating unit 70, the solvent attached to the standard particles is evaporated, and the standard particles can be dried.

  In (g), an aerosol composed of standard particles cooled or naturally cooled on the tube wall is generated.

  In addition, the mechanism mentioned in the principle mentioned above is given as an example for easy understanding, and is not limited to this.

  FIG. 3 is a schematic diagram illustrating the configuration of a single standard particle aerosol generator according to an embodiment of the present invention.

  Referring to FIG. 3, a single standard particle aerosol generator 100 according to an embodiment of the present invention includes an apparatus main body 10, a gas supply unit 20, a solution supply unit 30, and a control unit 90. The apparatus main body 10 heats an aerosol composed of a tube 12, a supply port 12 a for supplying gas (gas) into the tube, an inkjet head 42 provided in the tube, and droplets ejected from the inkjet head 42. The first heating unit 50 that evaporates the solvent in the air stream, the solvent vapor collection unit 60 that collects the vapor of the evaporated solvent, and the second heating unit 70 that generates the aerosol of the standard particles by heating the aerosol. And a cooling unit 80 that cools or naturally cools the heated aerosol of standard particles, and the generated aerosol of standard particles is taken out from the tube outlet 12b.

  The gas supply unit 20 supplies clean gas to the main body. The gas supply unit 20 stores a gas cylinder 21, a flow rate adjusting valve 22 that controls the gas flow rate, a filter 23, a flow meter 26, and a gas pipe. A pipe is provided for circulation to the supply port 12a of the body 12. The gas supply unit 20 further includes a filter 24 and an ON / OFF valve as a bypass of the gas flow path. Although gas is not specifically limited, Inert gas, such as air, nitrogen, Ar gas, is selected. The gas is preferably dehumidified, for example, dry air.

  The flow rate of the gas is preferably adjusted so that the flow inside the tube body 12 becomes a laminar flow. The flow rate of the gas inside the tube body 12 can be adjusted by the flow rate, for example, by the flow rate adjusting valve 22, whereby the aerosol is stably generated.

  The solution supply unit 30 includes a storage vial 32 that stores a standard particle dispersion that is an aerosol source, and a pipe 34 that distributes the standard particle dispersion. The standard particle dispersion includes a solvent having a viscosity higher than that of water and standard particles not dissolved in the solvent, and the standard particles are dispersed in the solvent.

  The standard particles are not particularly limited as long as they are not dissolved in a solvent described later. For calibration of an aerosol measuring instrument such as a light scattering airborne particle counter (OPC), standard particles having a known particle diameter are used. Such standard particles include polystyrene latex spheres, silica spheres and glass beads.

Further, the following standard particles can be used.
A fluorescent standard particle having a combination of different excitation and emission wavelength bands to simulate a living body,
-Standard particles with the ability to supplement the surface with different types of antibiotics,
-Standard particles surface-modified with functional groups such as carboxyl groups and amine groups.

  Standard particles having an average particle size of 20 μm or less can be used. In particular, it is preferable to use particles having a particle diameter of 2 μm to 20 μm for the evaluation of an aerosol measuring instrument for a micrometer particle size region. With the single standard particle aerosol generator 100 according to the present embodiment, standard particles having an average particle diameter of 2 μm to 20 μm, which has been difficult to realize in the past, can be aerosolized as single particles.

The solvent used for the standard particle dispersion is selected to have a higher viscosity than water (0.89). Thereby, gravity sedimentation of the standard particles in the standard particle dispersion can be suppressed, and the standard particles can be prevented from settling or floating in the flow path until the ink is ejected from the inkjet head 42. Examples of such a solvent include water-soluble solvents such as ethylene glycol (17.6), diethylene glycol (30.0), and triethylene glycol (37.8). Examples include dibutyl phthalate (20.9), oleic acid (28.8), linoleic acid (38.5) and dioctyl phthalate (71.8). Dipropylene glycol (65 .9) and methyldiethanolamine (76.5). The parentheses in this paragraph represent the viscosity at 25 ° C., and the unit is × 10 ⁻³ Pa · s. In addition to the solvents listed here, any solvent can be selected as long as it has a higher viscosity than water and does not dissolve the selected standard particles.

The number density of standard particles in the standard particle dispersion is preferably 5 × 10 ^{4 to} 1.5 × 10 ⁵ particles · mL ⁻¹ . As a result, the probability that two or more standard particles are included in one droplet discharged from the inkjet head 42 can be greatly reduced, and standard particles of single particles (single particles) can be aerosolized. In addition, a single particle aerosol can be obtained efficiently.

  Next, the apparatus main body 10 will be described below. The tubular body 12 may have a circular, triangular, quadrangular or other polygonal cross-sectional shape. The tube body 12 can be formed from, for example, metal, glass, and other materials, and is not particularly limited as long as it is a material that is not affected by the heat of the first heating unit 50 and the second heating unit 70.

  The tube body 12 is preferably provided along the direction of gravity, that is, provided upright. It is possible to prevent the droplets discharged from the inkjet head 42 and the aerosol thereof from coming into contact with the inner surface 12c of the tube body.

  The tube body 12 is provided with a supply port 12a for supplying gas. The supply port 12a is provided at a position higher than the inkjet head 42, and the inkjet head 42 is provided downstream of the gas flow introduced from the supply port 12a. By doing so, an undisturbed gas stream can be formed in the vicinity of the nozzle 42 a of the inkjet head 42.

  An ink jet head 42 can be used for the droplet discharge unit 40, and a continuous type (droplet generated by a vibrating orifice is generated) or a drop-on-demand (DOD) type (for example, a single vibration of a piezo element). One droplet is generated for each of them.) The DOD type ink jet head is preferable in that it can discharge a single droplet as a monomer and hardly generate satellite droplets.

In the ink jet head 42, the standard particle dispersion supplied from the storage vial 32 through the pipe 34 is filled and discharged into the nozzle 42a by the opening and closing operation of the nozzle to generate droplets. The opening diameter (diameter) at the tip of the nozzle 42a is appropriately selected according to the particle size of the standard particles to be used. When the particle size of the standard particles is 2 μm to 20 μm, for example, 70 μm is selected. When the number density of standard particles in the standard particle dispersion is 1.5 × 10 ⁵ particles · mL ⁻¹ , the generated droplets include a liquid containing one standard particle per 100 droplets. It has been found that on average 3 to 4 drops are generated. The droplets continuously ejected from the inkjet head 42 become aerosol and flow below the tube body 12 due to their own weight and gas flow. The inkjet head 42 is controlled by a personal computer (PC) 92 and a controller 94 of the control unit 90 with respect to the frequency of droplet generation, that is, the number of ejections per unit time.

  The first heating unit 50 and the second heating unit 70 are provided with heaters 52 and 72 so as to surround the tube body 12 on the tube body outer surface 12d, for example. The heat generated by the heaters 52 and 72 is conducted through the tube body 12 and heats the gas and aerosol inside the tube body. As a result, the solvent of the droplets or the solvent attached to the standard particles is evaporated. By heating again with the second heating unit 70, dried standard particles can be generated. The temperature setting of the heaters 52 and 72 is appropriately set depending on the gas flow rate and the type of solvent, and is, for example, 130 ° C. to 150 ° C. The control of the heating temperature may be controlled by a temperature control device provided in the heaters 52 and 72, or may be controlled by being connected to the PC 92.

  The solvent vapor collection part 60 is for collecting the solvent vapor in the aerosol containing gas. An example of the solvent vapor collection unit 60 will be described below.

  4-6 is a figure which shows the example of the solvent vapor collection part of the single standard particle aerosol generator which concerns on one Embodiment of this invention. 4 to 6 are illustrated such that the upper side is the first heating unit 50 and the lower side is the second heating unit 70. The droplets inside the tube, the standard particles, the solvent vapor, and the condensed solvent are shown as in FIG.

  Referring to FIG. 4, the solvent vapor collection unit 160 cools the pipe body 12 with a water-cooled cooler 162, and a cooling pipe 164 is provided on the pipe outer surface 12 d so as to surround the pipe body 12. The cooling water is communicated with the cooling pipe 164 to cool the pipe body 12, and the solvent vapor contained in the gas stream inside the pipe body is condensed on the inner surface of the pipe body. Thereby, the density | concentration of the solvent vapor | steam in airflow can be reduced.

  Referring to FIG. 5, the solvent vapor collector 260 is provided with an adsorbent 262 along the circumferential direction of the tube inner surface 12 c. The adsorbent can adsorb solvent vapor contained in the gas inside the tube and reduce the concentration of solvent vapor in the airflow. For example, activated carbon can be used as the adsorbent.

  Referring to FIG. 6, the solvent vapor collecting unit 360 includes a supply port 312a for introducing gas into the tube body 12 and a tube 312 coaxial with the tube body 12 and a downstream thereof. An outlet 312b is provided, and the gas flows along the inner surface of the tube body 312 in the same direction as the aerosol from the first heating unit 50. The solvent vapor in the aerosol diffuses into the introduced gas and is exhausted together with the gas from the outlet 312b. Thereby, the solvent vapor | steam contained in aerosol is discharged | emitted and the density | concentration of a solvent vapor | steam can be reduced. In addition, the gas supplied to the supply port 312a may be supplied from the gas supply part 20, and a gas supply part may be provided separately.

  Returning to FIG. 3, the cooling unit 80 may cool the aerosol of standard particles from the second heating unit 70 by natural cooling, or may use the water-cooled cooling system shown in FIG. 4. The aerosol of standard particles heated by the second heating unit 70 can be cooled.

  It should be noted that a CCD camera 95 and a strobe 96 may be provided outside the tube 12 at the position of the nozzle 42 a of the inkjet head 42 so that the droplet discharge state can be monitored from the window member 18. Further, a bipolar ion generation source 46 may be provided between the nozzle 42a and the first heating unit 50 to discharge the discharged droplets.

  According to this embodiment, since the standard particles are dispersed in a solvent having a viscosity higher than that of water, the standard particle dispersion liquid is supplied to the nozzle 42a of the inkjet head 42 and is discharged in the flow path until it is discharged. Can be prevented from settling or floating, and droplets containing single standard particles (single standard particles) can be ejected. At the same time, the solvent vapor in the air stream evaporated in the first heating unit 50 is collected in the solvent vapor collection unit 60 by condensation by cooling, adsorption by an adsorbent, or diffusion of the solvent vapor into the introduced gas. It is possible to suppress the vapor concentration of the solvent from adhering to the aerosol standard particles due to nuclear condensation or the like. Furthermore, by heating the aerosol in the second heating unit 70, it is possible to evaporate and remove the solvent adhering to the standard particles to generate an aerosol of standard particles.

  FIG. 7 is a flowchart illustrating a method for generating an aerosol of standard particles according to an embodiment of the present invention. Hereinafter, a method for generating a single standard particle aerosol according to an embodiment of the present invention will be described with reference to FIG.

  First, a standard particle dispersion is prepared by dispersing standard particles in a solvent having a viscosity higher than that of water, and is supplied to the droplet discharge unit 40 (S102). The standard particles and solvent described above are used. Examples of the method for dispersing the standard particles in a solvent include a bottle shaker and an ultrasonic bath. As described above, the generation of a droplet containing two standard particles is suppressed, and a droplet containing one standard particle in a solvent and a droplet containing only a solvent not containing a standard particle are generated. As described above, the number density of the standard particles of the standard particle dispersion is set.

  Next, the standard particle dispersion supplied to the ink jet head 42 is ejected into the air stream by the ink jet head 42 under the control of the PC 92 and the controller 94, etc., to generate liquid droplets, and the aerosol composed of the liquid droplets is generated (S104). .

  Next, the generated aerosol is heated (S106). This heating evaporates the solvent of the aerosol droplets and generates solvent vapor.

  Next, the vapor of the solvent in the aerosol is collected (S108). The collection method uses condensation by cooling, adsorption by an adsorbent, or diffusion of solvent vapor to the introduced gas and exhaust as shown in FIGS. This reduces the concentration of solvent vapor in the gas.

  Next, the aerosol with the reduced concentration of solvent vapor in the gas is heated (S110). Thereby, the solvent adhering to the standard particles is evaporated, and the fine particles can be dried. This step can generate an aerosol of standard particles.

  Next, the aerosol of heated standard particles is cooled (S112). This cooling may be natural cooling (cooling) or the water cooling system shown in FIG.

  According to the present embodiment, the standard particle dispersion is prepared by dispersing the standard particles in a solvent having a viscosity higher than that of water, and the standard particles are not dissolved in the solvent. The standard particles can be prevented from settling or floating in the flow path to the nozzle 42a, and the nozzle 42a can discharge a droplet containing a single standard particle (single standard particle). Become. The aerosol generated in this way is heated to evaporate the solvent, and this solvent vapor is collected, so the concentration of the solvent vapor in the gas is reduced, and the solvent vapor is condensed into the aerosol standard particles. It becomes possible to suppress adhering with. Furthermore, by heating the aerosol, it is possible to evaporate and remove the solvent adhering to the standard particles, thereby generating an aerosol of standard particles.

[Example]
As an example, the single standard particle aerosol generator 100 uses a single standard particle aerosol generator 100 shown in FIG. 3 and is ejected from a nozzle having a pore diameter of 70 μm with an MD-K-130 inkjet head manufactured by microdrop. . The first and second heating sections were set to 130 ° C. and 150 ° C., respectively, and the solvent vapor collection section was set to 2 ° C. with a water-cooled cooler shown in FIG. Standard particles were polystyrene latex (PSL) spheres manufactured by JSR having particle sizes of 7, 10, 15 and 20 μm, ethylene glycol was used as a solvent, and PSL spheres were dispersed in ethylene glycol. The viscosity of ethylene glycol at 25 ° C. is 17.6 × 10 ⁻³ Pa · s. The number density of PSL spheres per solution volume in the solution was adjusted to 5 × 10 ^{4 to} 1.5 × 10 ⁵ pieces · mL ⁻¹ . The particle generation frequency and particle size distribution of PSL spheres in the aerosol generated by this generator were measured with an aerodynamic spectrometer (APS) (TSI model 3321). The particle generation frequency is the number of detected PSL spheres of each particle size per unit time expressed as the number per second.

[Comparative example]
As a comparative example, the aerosol generator used was a single standard particle aerosol generator in which the solvent vapor collection section and the second heating section shown in FIG. 3 were not provided. The ink jet head and the nozzle diameter are the same as in the example. The first heating unit was set to 130 ° C., the standard particles used were the same as those in the example, and water (pure water) was used as the solvent. The viscosity of water at 25 ° C. is 0.89 × 10 ⁻³ Pa · s. The number density per solution volume in the solution of PSL spheres was set to the same number density as in the examples. The particle generation frequency and particle size distribution of PSL spheres in the aerosol generated by this single standard particle aerosol generator were measured by the same APS as in the examples.

  FIG. 8 is a graph showing the frequency of occurrence of polystyrene latex sphere particles in the aerosols of Examples and Comparative Examples according to the present invention. In the graph, black triangles (▲) indicate examples, and white squares (□) indicate comparative examples.

  Referring to FIG. 8, it can be seen that the aerosol can be continuously generated in the example over a longer time than the comparative example in any of the particle sizes of 7, 10, 15 and 20 μm. Furthermore, it can be seen that this phenomenon becomes more prominent as the particle size of the PSL sphere increases. In the case of the comparative example having a particle size of 20 μm, it was not aerosolized and could not be measured properly.

  FIG. 9 is a graph showing the particle size distribution of aerosol polystyrene latex spheres according to examples of the present invention. FIG. 9 shows the particle size distribution of the PSL spheres in the aerosol generated by the generator according to the example with respect to the case where the dispersions of the PSL spheres having the respective particle sizes indicated in the graph are used. is there.

  Referring to FIG. 9, PSL spheres of each particle size are analyzed by the single standard particle aerosol generator of the example, and one standard particle, that is, a monoparticulated PSL sphere is aerosolized. The

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications and changes can be made within the scope of the present invention described in the claims. Is possible.

  In addition, the standard particle aerosol generator described above uses a test particle such as a PSL sphere with a known particle size, so that an aerosol measuring instrument such as a light scattering air particle counter (OPC) or a condensed particle counter (CPC) can be used. It is needless to say that calibration is possible and a system combining the above-described standard particle aerosol generator and aerosol measuring device can be configured. In this specification, an apparatus and method for aerosolizing standard particles have been described. Needless to say, this apparatus and method can also aerosolize fine particles other than the standard particles whose particle sizes are not known. Yes.

In addition, the following additional notes are disclosed regarding the above description.
(Appendix 1) A device capable of generating an aerosol of a single standard particle,
A droplet discharge unit that generates aerosol by continuously discharging droplets of a solution in which the standard particles insoluble in the solvent are dispersed in a solvent having a viscosity higher than that of water into an air flow in a tube;
A first heating unit provided downstream of the droplet discharge unit to heat the aerosol and evaporate the solvent;
A solvent vapor collection unit that is provided downstream of the first heating unit and collects the vapor of the solvent in the aerosol;
A second heating unit that is provided downstream of the solvent vapor collection unit and generates the aerosol of the standard particles by heating the aerosol;
Comprising the apparatus.
(Additional remark 2) The said droplet discharge part has a nozzle which discharges the said solution,
The apparatus according to claim 1, wherein the solution is stored in the nozzle, and the nozzle separates a part of the stored solution and repeatedly discharges droplets.
(Additional remark 3) The said solvent vapor | steam collection part is an apparatus of Additional remark 1 or 2 which cools the vapor | steam of the solvent in the said aerosol, and condenses it on a tube wall.
(Additional remark 4) The said solvent vapor | steam collection part is an apparatus of Additional remark 1 or 2 formed by collecting the vapor | steam of the solvent in the said aerosol with adsorption agent.
(Supplementary Note 5) The solvent vapor collection unit is provided with a supply port for introducing gas into the tube body and a discharge port downstream thereof so that the gas flows along the inner surface of the tube wall in the same direction as the aerosol, The apparatus according to claim 1 or 2, wherein the vapor of the solvent in the aerosol is diffused into the gas and exhausted from the outlet.
(Additional remark 6) It further has a solution storage part which can store the above-mentioned solution,
The apparatus according to any one of appendices ¹ to ⁵ , wherein the solution is prepared such that the number concentration of standard particles per solvent volume is 5 × 10 ^{4 to} 1.5 × 10 ⁵ particles · mL ^−1. .
(Appendix 7) The apparatus according to any one of appendices 1 to 6, wherein the average particle diameter of the standard particles is 2 μm to 20 μm.
(Supplementary note 8) The apparatus according to any one of supplementary notes 1 to 7, wherein the standard particles are selected from standard particles having at least one standard particle size selected from the group consisting of polystyrene latex spheres, silica spheres, and glass beads.
(Supplementary Note 9) The solvent is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, dibutyl phthalate, oleic acid, linoleic acid, dioctyl phthalate, dipropylene glycol, and methyldiethanolamine. The apparatus according to any one of appendices 1 to 8.
(Supplementary note 10) The apparatus according to any one of supplementary notes 1 to 8, wherein the viscosity of the solvent at 25 ° C is 17 to 81 x 10 ^-3 Pa · s.
(Additional remark 11) The said pipe body is provided along the gravity direction, and the said droplet discharge part, the said 1st heating part, the said solvent vapor collection part, and the said 2nd heating are provided in this pipe body from the high side. The device according to any one of supplementary notes 1 to 10, wherein the parts are arranged in this order.
(Appendix 12) A method capable of generating an aerosol of a single standard particle,
A solution in which the standard particles insoluble in the solvent are dispersed in a solvent having a viscosity higher than that of water is supplied to the droplet discharge unit, and the droplet discharge unit continuously drops droplets into the airflow in the tube. Discharging to generate aerosol;
Heating the generated aerosol to evaporate the solvent;
Collecting vapor of the solvent in an aerosol from which the solvent has been evaporated;
Heating the aerosol from which the solvent vapor has been collected to generate an aerosol of the single standard particle;
Said method.
(Supplementary note 13) The method according to supplementary note 12, wherein the step of discharging the liquid droplets stores the solution in a nozzle, and the nozzle separates a part of the stored solution and repeatedly discharges the liquid droplets.
(Supplementary note 14) The method according to Supplementary note 12 or 13, wherein the step of collecting the vapor of the solvent cools the vapor of the solvent in the aerosol and condenses it on a tube wall.
(Supplementary note 15) The method according to Supplementary note 12 or 13, wherein the step of collecting the vapor of the solvent comprises collecting the vapor of the solvent in the aerosol with an adsorbent.
(Supplementary Note 16) In the step of collecting the vapor of the solvent, the gas flows in the same direction as the aerosol along the inner surface of the tube wall through the supply port for introducing the gas into the tube body and the discharge port downstream thereof. 14. The method according to appendix 12 or 13, wherein the vapor of the solvent in the aerosol is diffused into the gas and exhausted from the outlet.
(Additional remark 17) It further has a solution storage part which can store the solution,
The method according to any one of appendices 12 to 16, wherein the solution is prepared such that the number concentration of standard particles per solvent volume is 5 × 10 ^{4 to} 1.5 × 10 ⁵ particles · mL ^−1. .
(Additional remark 18) The method as described in any one of additional marks 12-17 whose average particle diameter of the said standard particle is 2 micrometers-20 micrometers.
(Supplementary note 19) The method according to any one of Supplementary notes 12 to 18, wherein the standard particles are selected from standard particles having at least one standard particle size selected from the group of polystyrene latex spheres, silica spheres, and glass beads.
(Supplementary note 20) The solvent is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, dibutyl phthalate, oleic acid, linoleic acid, dioctyl phthalate, dipropylene glycol, and methyldiethanolamine. The method according to any one of appendices 12 to 19.
(Supplementary note 21) The method according to any one of Supplementary notes 12 to 20, wherein the viscosity of the solvent at 25 ° C is 17 to 81 × 10 ^-3 Pa · s.
(Appendix 22) A device for generating aerosol of fine particles,
A liquid droplet ejection part that continuously ejects liquid droplets in a gas stream in a tube having a solution in which the fine particles insoluble in the solvent are dispersed in a solvent having a viscosity higher than that of water to generate aerosol;
A first heating unit provided downstream of the droplet discharge unit to heat the aerosol and evaporate the solvent;
A solvent vapor collection unit that is provided downstream of the first heating unit and collects the vapor of the solvent in the aerosol;
A second heating unit that is provided downstream of the solvent vapor collection unit and generates aerosol of the fine particles by heating the aerosol;
Comprising the apparatus.
(Supplementary note 23) A method of generating aerosol of fine particles,
A solution in which the fine particles insoluble in the solvent are dispersed in a solvent having a viscosity higher than that of water is supplied to the droplet discharge unit, and the droplet discharge unit continuously discharges droplets into the airflow in the tube. And generating aerosol,
Heating the generated aerosol to evaporate the solvent;
Collecting vapor of the solvent in an aerosol from which the solvent has been evaporated;
Heating the aerosol in which the vapor of the solvent is collected to generate the particulate aerosol;
Said method.

DESCRIPTION OF SYMBOLS 10 Apparatus main body 30 Solution supply part 40 Droplet discharge part 42 Inkjet head 50 1st heating part 52, 72 Heater 60, 160, 260, 360 Solvent vapor collection part 70 2nd heating part 100 Single standard particle aerosol generator

Claims (14)

A device capable of generating a single standard particle aerosol,
A droplet discharge unit that generates aerosol by continuously discharging droplets of a solution in which the standard particles insoluble in the solvent are dispersed in a solvent having a viscosity higher than that of water into an air flow in a tube;
A first heating unit provided downstream of the droplet discharge unit to heat the aerosol and evaporate the solvent;
A solvent vapor collection unit that is provided downstream of the first heating unit and collects the vapor of the solvent in the aerosol;
A second heating unit that is provided downstream of the solvent vapor collection unit and generates the aerosol of the standard particles by heating the aerosol;
Comprising the apparatus.   The apparatus according to claim 1, wherein the solvent vapor collecting unit cools and condenses the vapor of the solvent in the aerosol on the tube wall.   The apparatus according to claim 1, wherein the solvent vapor collecting unit collects the vapor of the solvent in the aerosol with an adsorbent.   The solvent vapor collection unit is provided with a supply port for introducing gas into the tube body and a discharge port downstream thereof so that the gas flows along the inner surface of the tube wall in the same direction as the aerosol. The apparatus according to claim 1, wherein solvent vapor is diffused into the gas and exhausted from the outlet.   The apparatus as described in any one of Claims 1-4 whose average particle diameters of the said standard particle are 2 micrometers-20 micrometers.   6. The apparatus according to any one of claims 1 to 5, wherein the standard particles are selected from at least one standard particle size standard particle from the group of polystyrene latex spheres, silica spheres and glass beads.   The solvent is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, dibutyl phthalate, oleic acid, linoleic acid, dioctyl phthalate, dipropylene glycol, and methyldiethanolamine. The apparatus according to any one of 6. A method capable of generating a single standard particle aerosol,
A solution in which the standard particles insoluble in the solvent are dispersed in a solvent having a viscosity higher than that of water is supplied to the droplet discharge unit, and the droplet discharge unit continuously drops droplets into the airflow in the tube. Discharging to generate aerosol;
Heating the generated aerosol to evaporate the solvent;
Collecting vapor of the solvent in an aerosol from which the solvent has been evaporated;
Heating the aerosol from which the solvent vapor has been collected to generate an aerosol of the single standard particle;
Said method.   9. The method of claim 8, wherein the step of collecting the solvent vapor cools the solvent vapor in the aerosol and condenses it on the tube wall.   9. The method according to claim 8, wherein the step of collecting the solvent vapor comprises collecting the solvent vapor in the aerosol by an adsorbent.   The step of collecting the vapor of the solvent includes a supply port for introducing gas into the tube body and a discharge port downstream thereof so that the gas flows along the inner surface of the tube wall in the same direction as the aerosol, The method according to claim 8, wherein the vapor of the solvent in the aerosol is diffused into the gas and exhausted from the outlet.   The method according to claim 8, wherein the standard particles have an average particle diameter of 2 μm to 20 μm.   13. A method according to any one of claims 8 to 12, wherein the standard particles are selected from at least one standard particle size standard particle from the group of polystyrene latex spheres, silica spheres and glass beads.   The solvent is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, dibutyl phthalate, oleic acid, linoleic acid, dioctyl phthalate, dipropylene glycol, and methyldiethanolamine. 14. The method according to any one of 13.

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