JP2017003384A - Particle measuring device and particle measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle measuring device and a particle measuring method using a condensation nucleus method capable of detecting microscopic particles in sampling gas with a high detection rate even when the sampling gas flows at a large flow rate.SOLUTION: A particle measuring device comprises: a saturated vapor production device 1 which produces high temperature saturated vapor; a condensation pipe 2 where the saturated vapor produced in the saturation vapor production device 1 and sampling gas including microscopic particles is introduced thereinto and condensation particles are generated in a manner that allows vapor molecules in the saturated vapor to be condensed with the microscopic particles in the sampling gas as nuclei; and a particle measuring section 4 which measures the number of the microscopic particles by measuring the number of condensation particles generated in the condensation pipe 2. Both the saturated vapor and the sampling gas are introduced into the condensation pipe 2 in laminar flows and a mixed flow of the saturated vapor and the sampling gas in the condensation pipe 2 also forms a laminar flow.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a particle measuring apparatus and a particle measuring method using a condensation nucleus method that grows particles by condensing vapor molecules using microparticles as nuclei and measures the number of particles.

  When manufacturing a semiconductor device, there are various processes such as film formation, photolithography, and etching. In these processes, if particles adhere to the semiconductor substrate, the performance of the formed device deteriorates. Therefore, it is necessary to install the processing apparatus in a clean room and perform processing in a clean atmosphere with very few particles.

  For this reason, it is required to quickly detect dust by measuring the number of particles in the processing apparatus or clean room with a measuring instrument. Condensed nucleus counters (CNC or CPC) that can measure nano-sized airborne particles are used as measuring instruments because particles affect the device performance even if they are nano-sized. .

  The condensation nucleus counter is used to pass particles through supersaturated vapors such as alcohol and water, and to condense the vapor molecules using the particles as nuclei, thereby growing the particles and detecting the grown particles at the detection unit. . The particle size at the detection limit of the detector due to light scattering is usually about 100 nm. However, since the condensed nucleus counter grows particles, it can detect particles of several nm.

  As such a condensation nucleus counter, Non-Patent Document 1 discloses that a supersaturated vapor is formed in a saturated portion, and then a sampling gas is introduced into the center of the condensation tube via a thin tube sampling nozzle, and sheath air is formed around it. The thing which suppresses adhesion to the wall of the particle | grains (particle) in sampling gas by flowing air called is described.

  Further, Non-Patent Document 2 discloses a vapor mixing type condensation nucleus counter that controls the growth size of particles by causing turbulent mixing of sampling gas and high-temperature saturated vapor to cause condensation and passing through a heat insulating tube. Is described.

  Furthermore, Non-Patent Document 3 describes the principle of the condensation nucleus counter and the results of performance evaluation of various condensation nucleus counters including those described in Non-Patent Documents 1 and 2.

Catalog TSI model 3025A Dr. Nobuhiko Fukushima Doctoral Thesis (1995) “Studies on Steam-Mixed Condensed Nucleus Counters and Their Applications” Chapters 1-2 and 3.2.2 (page 1-103) Kikuo Okuyama et al. Aerosol Research, 8 (3), pp. 200-211 (1993)

  By the way, recently, it is required to measure minute air particles having a low concentration of 100 nm or less, and in order to accurately measure such particles, it is necessary to increase the sampling flow rate.

  However, when the flow rate of the sampling gas is increased by the measuring instrument described in Non-Patent Document 1, the ejection speed of the sampling gas from the sampling nozzle that is a thin tube becomes extremely high. For this reason, the sampling gas becomes a turbulent flow, the condensed particles formed by condensing vapor molecules with the particles as nuclei adhere to the wall portion, and the detection rate becomes low. Increasing the diameter of the sampling nozzle reduces the flow velocity and suppresses turbulent flow, but produces a region with low saturation due to insufficient heat transfer and humidification from the wall. For this reason, there are not a few particles that do not grow to a size that can be detected, and the detection rate is still low.

  On the other hand, the vapor mixing type condensation nucleus counter described in Non-Patent Document 2 shows the feasibility of increasing the flow rate, but in order to mix sampling gas and high temperature saturated steam by turbulent mixing, As described in Non-Patent Document 3, condensed particles formed by condensation of vapor molecules using particles in sampling gas as nuclei are likely to adhere to the inner wall of the condensing tube, resulting in a low detection rate. There is sex.

  Therefore, an object of the present invention is to provide a particle measuring apparatus and a particle measuring method by a condensation nucleus method that can detect fine particles in a sampling gas at a high detection rate even when the sampling gas is increased in flow rate. .

  In order to solve the above problems, a first aspect of the present invention includes a saturated steam generator that generates high-temperature saturated steam, the saturated steam generated in the saturated steam generator is introduced, and includes a minute particle A sampling gas is introduced, a condensation tube in which condensed particles are formed by condensing vapor molecules in the saturated vapor with minute particles in the sampling gas as nuclei, and the number of condensed particles formed in the condensation tube is measured. A particle measuring unit for determining the number of the fine particles, and both the saturated vapor and the sampling gas are introduced into the condensation tube in a laminar flow state, and the saturated vapor and the sampling gas in the condensation tube Provided is a particle measuring apparatus characterized in that a mixed flow of sampling gas is made into a laminar flow.

  The second aspect of the present invention is that a high-temperature saturated vapor and a sampling gas containing fine particles are both introduced into the condensing tube in a laminar flow state, and the saturated vapor and the sampling gas are mixed in the condensing tube. The flow is a laminar flow, condensing vapor molecules in the saturated vapor with the minute particles in the sampling gas as nuclei in the condensation tube to form condensed particles, and the condensed particles formed in the condensation tube There is provided a particle measuring method characterized in that the number of the minute particles is obtained by measuring the number.

  It is preferable that the Reynolds number of the saturated vapor and the sampling gas introduced into the condensing tube and the Reynolds number of the mixed flow in the condensing tube are both smaller than 4000.

  The saturated vapor and the sampling gas can be configured to be introduced into the condensing tube so as to be parallel flow parallel to the longitudinal direction of the condensing tube by a sampling nozzle. In this case, the condensing tube has a stationary part that extends in one direction and the flow of the saturated vapor becomes a parallel flow, and the sampling nozzle is parallel to the axial direction of the stationary part at the center of the stationary part. It is preferable to be inserted so that

  The steam generator includes a main body container, an introduction part that introduces dry gas into the main body container, a liquid holding part that is provided on an inner wall of the main body container, holds the liquid, and heats the main body container to A heater for evaporating the liquid held in the holding unit, and the dry gas passes through the main body container in a swirling state, and heat of the heater and the vapor of the liquid at the wall of the main body container It is preferable that the dry gas is heated and humidified by the above, and is sent out as high-temperature saturated steam from the delivery unit.

  According to the present invention, the saturated vapor and the sampling gas are both introduced into the condenser tube in a laminar flow state, and the mixed flow of the saturated vapor and the sampling gas becomes a laminar flow in the condenser tube. Even when the flow rate is increased, the condensation particles are prevented from adhering to the inner wall of the condensing tube, and fine particles in the sampling gas can be detected with a high detection rate.

It is sectional drawing which shows the particle measuring device which concerns on one Embodiment of this invention. It is a figure which shows the preferable example of a steam generator, (a) is a longitudinal cross-sectional view, (b) is a cross-sectional view of a steam outlet part, (c) is a cross-sectional view of a clean air inlet part. It is sectional drawing which shows the steam generator used for the conventional vapor | steam mixing type condensation nucleus counter. It is the schematic which shows the dimension of the condensing tube and sampling nozzle at the time of performing the thermal fluid simulation of the particle measuring device which concerns on embodiment of this invention, and conditions. It is a figure which shows the flow of the gas inside a condensing tube when the diameter of a sampling nozzle is 5 mm, and 20 mm. It is a figure which shows the change of supersaturation about the case where the wall surface temperature is 20 degreeC, and the case where the wall surface temperature is 20 degreeC when the wall surface of a condensation tube is a heat insulation wall. FIG. 3 shows the result of analyzing the temperature change of the steam generator used in the conventional vapor mixing type condensation nucleus counter shown in FIG. 3 and the steam generator as a preferred example shown in FIG. 2 by thermal fluid simulation. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
<Configuration of particle measuring device>
FIG. 1 is a sectional view showing a particle measuring apparatus according to an embodiment of the present invention.

  The particle measuring apparatus 100 is configured as a vapor mixing type condensation nucleus counter, and includes a vapor generator 1, a condenser tube 2, a sampling nozzle 3, and a particle measuring unit 4.

  The steam generator 1 generates high-temperature saturated steam, and its structure is not particularly limited. As the steam generator 1, what has a main body container and the wick which is the porous sheet which has the water absorption provided in the inner wall can be used, for example. The wick is supplied with a liquid such as water or alcohol from a liquid tank. The wick is wetted by the liquid supplied from the liquid tank, and the liquid held in the wick evaporates when the wall portion of the main body container is heated by the heater. Then, a dry gas, for example, dry clean air is passed through the main body container, and this is heated and humidified by the vapor formed by evaporation of the liquid to generate high-temperature saturated vapor.

  The condensing pipe 2 has an introduction part 11 into which saturated steam is introduced, and a stationary part 12 that extends in a direction orthogonal to the introduction part 11 and in which saturated steam flows as a parallel flow. The saturated steam generated by the steam generator 1 is supplied to the inside. A curved pipe section 13 is provided between the introduction section 11 and the stationary section 12. The wall portion of the condenser tube 2 is a heat insulating wall made of a heat insulating material. In addition, you may comprise the wall part of the condensation pipe | tube 2 with a heat-transfer material, and may heat it to desired temperature from the outside. The diameter of the condensing tube 2 is set to be large so that a large flow rate is possible. For example, the condensing tube 2 has a diameter corresponding to the maximum detection area of the particle measuring unit 4. The condition for supplying saturated steam to the condenser tube 2 is set so that the saturated steam flow flowing in the condenser tube 2 becomes a laminar flow. For example, the flow rate or the like of the supplied saturated steam is adjusted so that the saturated steam flow becomes a laminar flow with respect to the diameter of the condenser tube 2.

  The sampling nozzle 3 is inserted in the central part of the stationary part 12 of the condensing tube 2 so as to be parallel to the axial direction of the stationary part 12, and samples a gas containing nano-level microparticles from a clean room or the like. 2 is introduced into the condensing tube 2 so as to have a parallel flow parallel to the longitudinal direction. The temperature of sampling gas is about 15-30 degreeC, and the wall part of the sampling nozzle 3 is a heat insulation wall comprised with the heat insulation material.

  The sampling nozzle 3 has such a length that the sampling gas can be supplied to a portion where the saturated vapor flow becomes a parallel flow in the stationary portion 12 of the condensing tube 2.

  From the sampling nozzle 3, a sampling gas having a larger flow rate than the conventional one is supplied. The flow rate of the sampling gas is 1 to 100 L / min. The conditions are set so that the sampling flow supplied from the sampling nozzle 3 into the condensing tube 2 becomes a laminar flow. Specifically, the diameter of the sampling nozzle 3 is set so that the sampling flow supplied from the sampling nozzle 3 into the condensing tube 2 becomes a laminar flow corresponding to the flow rate of the supplied sampling gas. For example, if the sampling gas flow rate is about 50 L / min, the diameter of the sampling nozzle 3 is set to about 20 mm. When the diameter of the sampling nozzle 3 is reduced to increase the flow rate (flow velocity), the sampling gas flow (sampling flow) may become turbulent.

  In the steady portion 12 of the condenser tube 2, the saturated vapor flow and the sampling flow are mixed in a laminar flow state to form a mixed flow in a laminar flow state. In the case of this example, the laminar saturated vapor flow and the laminar sampling flow flow and mix in parallel, so the mixed flow inevitably becomes laminar. When mixing is performed in a state where the vapor flow and the sampling flow in the laminar flow state are orthogonal to each other, it is necessary to adjust the flow rate condition and the like so that the mixed flow becomes a laminar flow.

The state of the flow can be expressed by the Reynolds number Re expressed by the following formula. The larger the Re, the greater the disturbance of the flow. In order for the saturated vapor flow, the sampling flow, and the mixed flow to have a desired laminar flow state in the condenser tube 2, it is preferable that the Reynolds number Re of the saturated vapor flow, the sampling flow, and the mixed flow is smaller than 4000.
Re = ρVd / μ
Where ρ is the density (atmosphere, saturated steam), V is the flow velocity, d is the inner diameter [m] of the tube, and μ is the viscosity (atmosphere, saturated steam).

  Then, by mixing the saturated vapor flow and the sampling flow, the vapor molecules in the saturated vapor flow are condensed with the fine particles of about 100 nm or less in the sampling flow as the nucleus, and can be measured by the particle measuring unit 4. The particles grow to a degree or more.

  The degree of particle growth at this time is from the temperature corresponding to the wall surface temperature of the condenser tube 2 and the degree of supersaturation of the saturated vapor, from the position corresponding to the tip of the sampling nozzle 3 in the stationary part 12 of the condenser tube 2 to the end of the particle measuring part 4 The residence time, saturation steam, sampling flow rate, etc. The residence time is determined by the flow rate of the saturated vapor and the sampling flow and the length from the position corresponding to the tip of the sampling nozzle 3 in the stationary part 12 of the condenser tube 2 to the particle measuring part 4.

  The wall surface temperature of the condenser 2 is preferably 40 to 60 ° C., the degree of supersaturation of saturated steam is preferably about 1 to 2, and the residence time is preferably about 0.1 to 1 sec, for example about 0.2 sec. Moreover, when the flow rate of the sampling gas is 1 to 100 L / min as described above, the flow rate of the saturated vapor supplied to the condensing tube 2 is preferably 0.2 to 20 L / min.

  The particle measuring unit 4 determines the number of particles in the gas by measuring the number of condensed particles formed in the condensing tube 2, and a generally used optical particle measuring instrument can be used. . Among these, an optical system capable of measuring a wide range of particles is preferable. The particle measuring unit 4 includes a housing 21, a laser oscillator 22 that irradiates laser light into the housing 21, and a detector 23 that receives scattering holes generated by the particles when condensed particles pass through the laser light. The number of particles is measured by converting the received scattered light into an electrical signal.

  An exhaust port 24 is formed in the housing 21, and a pipe 25 is connected to the exhaust port 24. The pipe 25 is connected to the inlet of the saturated steam generator 1. The pipe 25 is provided with a pump 26, a filter 27, and the like. The filter 27 removes moisture and foreign matter from the gas discharged from the particle measuring unit 4 and supplies the gas to the saturated steam generator 1 as dry gas, for example, clean air.

<Operation of particle measuring device>
In the particle measuring apparatus 100 configured as described above, the pump 26 is operated, and dry clean air is passed through the steam generator 1 as dry gas, and liquid such as water or alcohol is heated with a heater therein. High temperature saturated steam is generated by the steam generated by

  The saturated steam generated by the steam generator 1 is supplied to the condenser tube 2 in a laminar flow state. At this time, conditions such as the flow rate of the saturated steam are set so that the flow of the saturated steam in the condensation pipe 2 becomes a laminar flow.

  On the other hand, the sampling gas is supplied into the condensing tube 2 from the sampling nozzle 3 in a laminar flow state. The flow rate of the sampling gas at this time is preferably 1 to 100 L / min. At this time, the diameter of the sampling nozzle 3 is set in accordance with the flow rate of the sampling gas so that the sampling flow supplied from the sampling nozzle 3 into the condensing tube 2 becomes a laminar flow.

  Sampling gas is supplied from the sampling nozzle 3 to the portion where the saturated vapor is in parallel flow in the condenser tube 2, and the saturated vapor flow and the sampling flow are mixed in a laminar flow state to form a mixed flow in a laminar flow state. The That is, the saturated vapor flow, the sampling flow, and the mixed flow are all made into a laminar flow state in the condensation pipe 2. At this time, the Reynolds number Re is preferably smaller than 4000 in any of the saturated vapor flow, the sampling flow, and the mixed flow.

  Then, by mixing the saturated vapor flow and the sampling flow, the vapor molecules in the saturated vapor flow are condensed using the fine particles of about 100 nm or less in the sampling flow as nuclei, and the particles grow to about the submicron size or more.

  The degree of particle growth at this time is from the temperature corresponding to the wall surface temperature of the condenser tube 2 and the degree of supersaturation of the saturated vapor, from the position corresponding to the tip of the sampling nozzle 3 in the stationary part 12 of the condenser tube 2 to the end of the particle measuring part 4 The residence time, saturation steam, sampling flow rate, etc.

  In order to grow into a particle system that can be reliably measured by the particle measuring unit 4, the wall surface temperature of the condensation tube 2 is preferably 40 to 60 ° C., the degree of supersaturation of saturated steam is preferably about 1 to 2, and the residence time is About 0.1 to 1 sec, for example, about 0.2 sec is preferable. Moreover, when the flow rate of the sampling gas is 1 to 100 L / min as described above, the flow rate of the saturated vapor supplied to the condensing tube 2 is preferably 0.2 to 20 L / min.

  Condensed particles formed by condensing vapor molecules with fine particles as nuclei in the condensation tube 2 are sent to the particle measuring unit 4 where the number of particles is measured.

  In this case, in this embodiment, the saturated vapor flow flows in the laminar flow state in the condensing tube 2, the sampling flow supplied from the sampling nozzle 3 is also supplied in the laminar flow state, and these are mixed in the laminar flow state. The mixed flow is also a laminar flow. For this reason, even when the sampling gas is increased in flow rate, it is possible to suppress the condensation particles from adhering to the inner wall of the condensing tube 2 and to detect fine particles in the sampling gas with a high detection rate. Further, by optimizing the conditions such as the temperature and the degree of saturation of the saturated vapor, it is possible to reliably condense the vapor molecules into the fine particles in the condensing tube 2 and to further increase the detection rate of the fine particles.

<Preferred example of steam generator>
Next, a preferable example of the steam generator 1 will be described.
FIG. 2 is a view showing a preferred example of the steam generator, in which (a) is a longitudinal sectional view, (b) is a transverse sectional view of the steam outlet portion, and (c) is a transverse sectional view of the clean air inlet portion.

  The steam generator 1 of this example includes a cylindrical main body container 31, an introduction pipe 32 for introducing dry gas such as clean air provided at one end of the main body container 31, And a delivery pipe 33 for delivering saturated steam provided at the other end. Both the introduction pipe 32 and the delivery pipe 33 are connected so that the axial direction thereof is the tangential direction of the circumferential side surface of the main body container 31.

  A central bar 34 having a cylindrical shape is provided at the center of the main body container 31 from one end to the other end. Further, a wick 35 that is a porous sheet having water absorption is provided on the entire inner wall of the main body container 31 and the entire surface of the center bar 34. Further, a heater 36 is provided around the main body container 31. Further, a liquid tank (not shown) for supplying a liquid such as water or alcohol to the wick 35 is provided.

  In the steam generator 1 configured as described above, a dry gas such as dry clean air is introduced into the main body container 31 through the introduction pipe 32. At this time, since the introduction pipe 32 and the delivery pipe 33 are provided so as to be in the tangential direction of the circumferential side surface of the main body container 31, a dry gas such as dry clean air introduced into the main body container 31 from the introduction pipe 32. 2 is a flow along the circumferential direction, and a swirl flow as shown in FIG. 2A is formed in the main body container 31, reaches the delivery pipe 33 while maintaining the swirl flow, and is sent from the feed pipe 33. Is done.

  On the other hand, a liquid such as water or alcohol is supplied and held from a liquid tank (not shown) to the wick 35, and the liquid is evaporated by being heated by the heater 36. The dry gas supplied to the main body container 31 becomes a swirl flow, so that the time during which the dry gas is heated and humidified from the wall surface side of the main body container 31 becomes long, and even when a large amount of dry gas is supplied, it is sufficient. It can be heated to a temperature and a sufficient degree of supersaturation can be obtained.

  As shown in FIG. 3, the steam generator used in the conventional vapor mixing type condensation nucleus counter is provided with a wick 44 on the entire inner wall of one end side and the other end side of a cylindrical container body 41. The dry gas passes in the axial direction of the container body 41. Further, a liquid such as water or alcohol is supplied and held from a liquid tank (not shown) to the wick 44, and the liquid evaporates when heated by a heater (not shown). Thus, the dry gas passing through the main body container 41 is heated and humidified, and is sent out from the delivery pipe 43 as saturated steam.

  However, the steam generator shown in FIG. 3 has a wick 44 with respect to the supplied flow rate of the dry gas when the flow rate of the dry gas for forming saturated steam increases with an increase in the flow rate of the sampling gas. It is difficult to efficiently heat and humidify the dry gas.

  On the other hand, the steam generator of FIG. 2 can form a swirl flow of dry gas in the main body container 31, so even if the dry gas has a large flow rate, it is more efficient than the steam generator of FIG. It is possible to generate saturated steam at a desired temperature and humidity by heating and humidifying.

<Simulation results>
Next, the thermal fluid simulation result of the particle measuring apparatus of this embodiment will be described.

(First simulation result)
Here, a condenser tube and a sampling nozzle having dimensions (mm) as shown in FIG. 4 are used, water is used as the liquid, the temperature of the saturated vapor is 90 ° C., the flow rate is 10 L / min, and the sampling gas is large at 25 ° C. Gas flow and gas diffusion inside the condenser tube were analyzed using ANSYS-FLUENT, a thermal fluid software, using dry air at atmospheric pressure and a flow rate of the mixed flow of 60 L / min.

  FIG. 5 is a diagram showing the gas flow inside the condensing tube when the diameter of the sampling nozzle is 5 mm and when it is 20 mm. As shown in this figure, when the diameter of the sampling nozzle is 5 mm, turbulent flow is generated inside the condensing tube, but it was confirmed that the flow inside the condensing tube becomes laminar when the diameter of the sampling nozzle is 20 mm. The Reynolds number when the sampling nozzle diameter was 5 mm was 14,000, whereas the Reynolds number when the sampling nozzle diameter was 20 mm was 3500.

  Next, when the residence time from when the dry air was discharged from the sampling nozzle to the exit from the condenser tube and the degree of supersaturation therebetween were determined, the residence time was about 0.2 sec under the simulation conditions of FIG. It was 1 to 2, which was almost the same as the condensation tube of a commercially available condensation nucleus counter, and it was confirmed that vapor molecules were sufficiently condensed.

  Next, when the wall surface of the condenser tube was a heat insulating wall, the change in supersaturation degree was grasped when the wall surface temperature was 20 ° C. and when the wall surface temperature was 60 ° C. FIG. 6 is a diagram showing the results at that time. As shown in FIG. 6, when the wall surface is a heat insulating wall and the wall surface temperature is 60 ° C., the supersaturation degree is 1 to 2 and is a range suitable for water condensation, but the wall surface temperature is as low as 20 ° C. It was confirmed that the degree of supersaturation becomes too high.

(Second simulation result)
Here, the steam generator used in the conventional conventional steam mixing type condensation nucleus counter shown in FIG. 3 and the steam generator which is a preferred example shown in FIG. The temperature change was analyzed using ANSYS-FLUENT, which is thermal fluid software, under the conditions of a flow rate and a temperature of 10 L / min and 25 ° C. The result is shown in FIG. As shown in FIG. 7, in the steam generator of FIG. 3, the temperature rise of the delivered steam is insufficient, but it was confirmed that the preferred example of FIG. 2 has a sufficiently high temperature.

  Further, the supersaturation degree of the delivered steam tended to be too high in the steam generator of FIG. 3, but it was confirmed that the preferred example of FIG.

<Other applications>
The present invention can be variously modified without being limited to the above embodiment. For example, in the above-described embodiment, the example in which the sampling nozzle is provided so as to be parallel to the condensing tube in the portion where the parallel flow of the condensing tube is formed is shown. The supply mode is not limited as long as it is supplied in a flow state and the mixed flow is a laminar flow.

DESCRIPTION OF SYMBOLS 1; Steam generator 2; Condensation pipe 3; Sampling nozzle 4; Particle measurement part 11; Introduction part 12; Steady part 21; Housing | casing 22; Laser oscillator 23; Filter 31; Main body container 32; Inlet port 33; Outlet port 35; Wick 36; Heater 100; Particle measuring device

Claims (10)

A saturated steam generator for generating high-temperature saturated steam;
The saturated steam generated by the saturated steam generator is introduced, a sampling gas containing minute particles is introduced, and condensed particles in which the vapor molecules in the saturated steam are condensed using the minute particles in the sampling gas as nuclei A condensation tube formed with,
A particle measuring unit for determining the number of fine particles by measuring the number of condensed particles formed in the condensation tube;
The saturated vapor and the sampling gas are both introduced into the condensing tube in a laminar flow state, and the mixed flow of the saturated vapor and the sampling gas is formed into a laminar flow in the condensing tube. Particle measuring device.   2. The particle measuring apparatus according to claim 1, wherein a Reynolds number of the saturated vapor and the sampling gas introduced into the condensing tube and a Reynolds number of the mixed flow in the condensing tube are both smaller than 4000.   3. The particle according to claim 1, wherein the saturated vapor and the sampling gas are introduced into the condensing tube by a sampling nozzle so as to have a parallel flow parallel to a longitudinal direction of the condensing tube. Measuring device.   The condensing tube has a stationary part that extends in one direction and the flow of the saturated vapor becomes a parallel flow, and the sampling nozzle is parallel to the axial direction of the stationary part at the center of the stationary part. The particle measuring apparatus according to claim 3, wherein the particle measuring apparatus is inserted.   The steam generator includes a main body container, an introduction part that introduces dry gas into the main body container, a liquid holding part that is provided on an inner wall of the main body container, holds the liquid, and heats the main body container to A heater for evaporating the liquid held in the holding unit, and the dry gas passes through the main body container in a swirling state, and heat of the heater and the vapor of the liquid at the wall of the main body container The particle measuring apparatus according to any one of claims 1 to 4, wherein the dry gas is heated and humidified by the air and is sent out as high-temperature saturated steam from the delivery part. High-temperature saturated vapor and sampling gas containing fine particles are both introduced into the condensing tube in a laminar flow state, and the mixed flow of the saturated vapor and the sampling gas is laminar in the condensing tube,
Condensing vapor molecules in the saturated vapor with fine particles in the sampling gas as nuclei in the condensation tube to form condensed particles,
A particle measuring method, wherein the number of fine particles is obtained by measuring the number of condensed particles formed in the condensation tube.   The particle measurement method according to claim 6, wherein both the Reynolds number of the saturated vapor and the sampling gas introduced into the condensing tube and the Reynolds number of the mixed flow in the condensing tube are smaller than 4000.   8. The particle according to claim 6, wherein the saturated vapor and the sampling gas are introduced into the condensing tube by a sampling nozzle so as to become a parallel flow parallel to a longitudinal direction of the condensing tube. Measurement method.   The condensing tube has a stationary part that extends in one direction and the flow of the saturated vapor becomes a parallel flow, and the sampling nozzle is parallel to the axial direction of the stationary part at the center of the stationary part. The particle measuring method according to claim 8, wherein the particle measuring method is inserted.   The saturated steam is generated by passing a dry gas in a swirling state through a main body container of a steam generator, and heating and humidifying the dry gas at a wall portion in the main body container. The particle measurement method according to claim 6, wherein the particle measurement method is a particle measurement method.