JPH05312710A - Measuring apparatus for concentration of ultra fine particle in gas - Google Patents

Abstract

PURPOSE:To obtain a measuring apparatus for measuring the concentration of ultrafine floating particles of 0.1mum or smaller particle size in a gas with high accuracy without contaminating the measuring environment or giving adverse influences to an operator. CONSTITUTION:In the concentration measuring apparatus for measuring the concentration of ultrafine particles in a gas, a sample air 1 including floating fine particles is classified by an electrostatic classifier 14. Steam of the super pure water generated in a condensable air generating part 5 is mixed with the sample air in a mixer 2. Liquid drops 16 formed when the mixture is cooled are counted in a particle counting part 3 by scattering of a laser light. The steam of the super pure water is used as a condensable gas, and a container 2 is the mixer into which the steam of the super pure water is introduced. The sample air 1 is sent into the container 2, where the steam of the super pure water and the sample air 1 are mixed and cooled in gas phase thereby to generate drops of the super pure water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the concentration of ultrafine particles in a gas having a particle size of 0.1 μm or less.

[0002]

2. Description of the Related Art In the production of ultrafine particles used in advanced industries, powder industry, atmospheric environmental pollution, hygiene, medical and semiconductor clean rooms, etc., the particle diameter of particles suspended in gas, especially in the atmosphere, is 0.1 μm or less. It is important to measure ultrafine particles. Conventionally, when measuring the concentration of suspended particles in a gas having a particle diameter of 0.1 μm or less, the suspended particles are used as condensation nuclei to generate droplets of a condensable gas, that is, non-uniform condensation is generated, and the particles are apparent. A method of counting droplets by utilizing a laser light scattering counting method by fertilizing to above 0.1 μm is adopted.

[0003]

That is, as shown in FIG. 3, when the non-uniform condensation is generated by using the suspended fine particles as the nucleus, the suction pump 07 is operated and the sample gas 01 containing the suspended fine particles is electrostatically classified. After being classified by 014, it is guided to the condensable gas generation unit 05, the sample gas and the condensable gas are mixed, and droplet condensation is generated in the downstream cooling unit (wall surface cooling) 013. After that, the number of droplets is counted by the measuring unit 03 using laser light scattering. However, in such a means, the cooling for generating the droplet condensation is wall cooling, so that the condensable gas easily condenses on the cooling section wall surface, and an appropriate supersaturated state for generating the droplet condensation is achieved. Hard to be done. Therefore, there is a problem that particles do not grow to 0.1 μm or more, particles are not counted sufficiently, and because butyl alcohol, which is harmful to the human body, is used as a condensable gas, However, there are problems such as pollution of the environment where the device is used and adverse effects on the human body.

The present invention has been proposed in view of the above circumstances, and it is possible to measure the concentration of suspended fine particles having a particle diameter of 0.1 μm or less with high accuracy without contamination of the measurement environment and adverse effects on workers. An object is to provide an ultrafine particle concentration measuring device.

[0005]

To this end, according to the present invention, a sample air containing suspended fine particles is introduced and classified by an electrostatic classifier, and the condensable gas generated in the condensable gas generating section and the sample gas are In a device for measuring the concentration of ultrafine particles in a gas, in which a droplet generated by mixing and cooling in a mixer is measured by a laser light scattering particle counting unit, ultrapure water vapor is used as the condensable gas. The sample air is introduced as a mixer into a container into which ultrapure water vapor is introduced, and both are mixed in a gas phase for cooling to generate water droplets of ultrapure water.

[0006]

According to such a structure, since it is a vapor phase mixed cooling method, condensation of the condensable gas on the wall surface of the apparatus is eliminated, and an appropriate supersaturated state for nucleating suspended fine particles is easily achieved, Effectively droplets are generated. As a result, fine particles having a particle size of 0.1 μm or less are likely to grow to 0.1 μm or more, and are sufficiently counted by laser light scattering. In addition, since ultrapure water vapor is used as the condensable gas, and the droplets and water vapor are removed by a filter and a dehumidifier and exhausted to the outside of the apparatus, problems such as adverse effects on the human body and environmental pollution are eliminated.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall system diagram thereof, and FIG. 2 is an enlarged view showing a vapor phase mixing / cooling unit of FIG.

A major difference of the apparatus of the present invention from the conventional apparatus shown in FIG. 3 is that the droplet condensation is generated in the cooling section by gas phase cooling instead of wall cooling. .. That is, first, in FIG. 1, the present apparatus includes a laser light scattering particle counting unit 3, an ultrapure water tank 11, an ultrapure water vapor generating unit 5, a vapor phase mixing and cooling unit 2, a suction pump 7, a dehumidifier 8, a filter. 9, flow meter 6, electrostatic classifier 14, steam flow rate adjusting valve 15
Etc. Here, 1 is sample air, 4 is ultrapure water, 10 is exhaust, 16 is water drop, 17 is relative humidity meter, 1
Reference numeral 8 is a temperature / pressure gauge for sample air, and 19 is a temperature / pressure gauge for water vapor.

In such an apparatus, first, when the suction pump 7 is operated, the sample air 1 is discharged into the electrostatic classifier 14.
And is introduced into the device through the electrostatic classifier 14 at that time.
When passing through, ultrafine particles in the sample air 1 are classified. Next, the water vapor from the ultrapure water vapor generating unit 5 and the sample air 1 are mixed in the gas phase mixing and cooling unit 2, and the water droplets 16 are generated by using the ultrafine particles in the sample air as condensation nuclei. Here, in the gas-phase mixture cooling unit 2, as shown in FIG.
Ultrapure water vapor of about 0 ° C. and sample air of about room temperature to 30 ° C. are mixed in a vapor phase to cool the water vapor,
The suspended fine particles contained in the sample air are used as a condensate to generate water droplets of ultrapure water. When the amount of water vapor condensed on the wall surface of the cooling unit increases, the amount of water vapor condensed on the ultrafine particles decreases, and as a result, it becomes difficult to enlarge the ultrafine particles due to the water vapor. Reduce. In this way, the generated water droplets are measured by the laser light scattering particle counting unit 3, and after counting the particles, the air containing the water droplets is dehumidified by the dehumidifier 8, and the water droplets remaining in the air are removed by the filter 9 to the outside of the apparatus. Exhaust 1
Zeroed. Furthermore, the degree of supersaturation of water vapor achieved in the gas-phase mixing / cooling unit 2 depends on the temperature, pressure, flow rate of the sample air,
Calculated based on relative humidity, water vapor temperature, pressure, and flow rate,
The suction pump flow rate and the steam flow rate adjusting valve 15 are adjusted so that a predetermined value is set.

Here, in the ultrapure water vapor generating section 05, a heater that does not generate impurities in the ultrapure water is used from the contact surface between the heater and the ultrapure water, or microwave heating is performed like a microwave oven. I do.

[0011]

According to such a device, the following effects can be obtained. (1) In the gas-phase mixing / cooling unit, the condensation of the condensable gas on the wall surface is eliminated, and an appropriate supersaturated state for nucleating the suspended fine particles is easily generated.
Floating particles of m or less easily grow to 0.1 μm or more, and the concentration measurement accuracy by laser light scattering is improved. (2) Since the water vapor of ultrapure water, which is harmless to the human body, is used as the condensable gas, it is not necessary to use butyl alcohol, which is harmful to the human body, so that environmental pollution due to exhaust gas and adverse effects on the human body occur. Absent.

In short, according to the present invention, sample air containing suspended fine particles is introduced and classified by the electrostatic classifier, and the condensable gas generated in the condensable gas generating section and the sample gas are mixed in the mixer. In a device for measuring the concentration of ultrafine particles in a gas, in which droplets generated by mixing and cooling are measured by a laser light scattering particle counting unit, ultrapure water vapor is used as the condensable gas, and the mixer is used. As a sample air was introduced into a container in which ultrapure water vapor was introduced, and both were mixed and cooled in a gas phase to generate water droplets of ultrapure water, the concentration of suspended fine particles having a particle diameter of 0.1 μm or less was obtained. The present invention is extremely useful industrially, because an ultrafine particle concentration measuring device in a gas can be measured with high accuracy without contamination of the measuring environment and adverse effects on workers.

[Brief description of drawings]

FIG. 1 is an overall system diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged view showing a vapor phase mixing / cooling unit of FIG.

FIG. 3 is a system diagram showing a conventional device for measuring the concentration of airborne particulates.

[Explanation of symbols]

 1 Sample Air 2 Gas Phase Mixing Cooling Section 3 Laser Light Scattering Particle Counting Section 4 Ultrapure Water 5 Ultrapure Water Vapor Generation Section 6 Flow Meter 7 Suction Pump 8 Dehumidifier 9 Water Drop Collection Filter 10 Exhaust 11 Ultrapure Water Tank 14 Electrostatic classifier 15 Flow rate control valve 16 Water drop 17 Relative hygrometer 18 Temperature / pressure gauge for sample air 19 Temperature / pressure gauge for water vapor

Claims (1)

[Claims] 1. A sample air containing suspended fine particles is introduced and classified by an electrostatic classifier, and the condensable gas generated in the condensable gas generating section and the sample gas are mixed and cooled in a mixer. In a device for measuring ultrafine particle concentration in a gas, in which a droplet generated is measured by a laser light scattering particle counting unit, ultrapure water vapor is used as the condensable gas, and ultrapure water vapor is used as the mixer. A device for measuring ultrafine particle concentration in air, characterized in that sample air is introduced into the introduced container and both are mixed and cooled in a gas phase to generate water droplets of ultrapure water.