JP2011013157A - Measuring device of suspended particulate matter, and preservation device of the suspended particulate matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device of suspended particulate matter suppressing volatilization of volatile components other than moisture in the suspended particulate matter, when dehumidifying air to be served to weight measurement of the suspended particulate matter.SOLUTION: This device for collecting fine particles in the suspended particulate matter in the atmosphere comprising the fine particles whose particle size is below a prescribed value and gross particles whose particle size exceeds the prescribed value, and measuring the mass of the collected fine particles includes: a classification means for sucking sample air including the suspended particulate matter, removing the gross particles from the sucked sample air, and acquiring fine particle-including air including the fine particles; a drying means for generating mixed air by a mixer by mixing dry air from which the suspended particulate matter is removed, and which is generated by non-heating drying process with the fine particle-including air, to thereby dehumidify the fine particles in the mixed air in the non-heating state; a collection means for collecting the fine particles onto a first filter by guiding the mixed air to the first filter; and a weight measuring means for measuring the weight of the fine particles collected onto the first filter.

Description

  The present invention relates to an apparatus for measuring suspended particulate matter, and more particularly to an apparatus for continuously measuring suspended particulate matter in the atmosphere, and more particularly to an apparatus for continuously measuring minute suspended particulate matter that has a great influence on human health.

  There are suspended particulate matter having various particle sizes in the atmosphere. The suspended particulate matter having a particle size of 10 μm or less is particularly toxic to humans because it is sucked and settled in the lung without being filtered by the respiratory tract when a person breathes. For this reason, the environmental standards related to air pollution based on the Pollution Control Basic Law stipulate that the suspended particulate matter in the atmosphere has a particle size of 10 μm or less. Conventionally, an apparatus for measuring the weight of suspended particulate matter having a particle size of 10 μm or less is commercially available according to this rule. In this specification, what is described as a suspended particulate matter is not limited to a particulate matter having a particle size of 10 μm or less, but is assumed to be a particulate matter suspended in the atmosphere.

  Airborne particulate matter includes coarse particles (hereinafter abbreviated as CP) and fine particles (hereinafter abbreviated as FP) with a particle size of about 2.5 μm as a boundary. Exists.

  CP contains naturally occurring things such as sea salt particles and dust derived from soil. FP, on the other hand, produces primary particles directly released into the atmosphere from sources such as dust and diesel vehicles emitted from factories, sulfur oxides (SOx), nitrogen oxides (NOx), and volatile organic compounds. There are secondary generated particles in which a gaseous substance such as (VOC) changes into a particulate substance in the atmosphere. Recently, as a result of epidemiological studies on the human body about the particle size of airborne particulate matter in urban areas, FP is thought to affect diseases such as cardiovascular disease, lung cancer and asthma even at low concentrations. Increased weight concentrations are believed to increase mortality.

  Patent Document 1 describes an apparatus for continuously measuring the weight of suspended particulate matter contained in a certain atmosphere. This device sucks the sample atmosphere containing suspended particulate matter, collects the suspended particulate matter contained in the sucked sample atmosphere on a filter, and measures the collected suspended particulate matter by the β-ray absorption method To do. For the measurement of suspended particulate matter, conventionally, manual analysis (manual analysis) using a weighing instrument has been performed. In this manual analysis, the suspended particulate matter collected on the filter is conditioned at a predetermined humidity (50%) before weighing. Therefore, in the measurement apparatus of Patent Document 1, in order to bring the measurement conditions closer to the conventional manual analysis, the sample air sent to the weight measurement unit is heated by the heater unit at a stage before being sent, so that the suspended particulate matter The relative humidity of the surrounding air is lowered so that the humidity of the sample air used for measurement matches the conditions of manual analysis.

  By the way, in the United States, the standard measurement method for suspended particulate matter (Federal Register Vol.62, No.138 / Appendix L: Abbreviated FRM method) has been established and a great deal of experimental data has been accumulated, especially for epidemiology. It is highly useful as data.

  In the measurement by the FRM method, classification is performed by a classifier using an air sampling device, and FP is sampled on the filter at a constant flow rate once a day, and then the filter is manually brought back to the laboratory. Control set temperature 15-30 ° C (error range at each control set temperature is ± 5 ° C), control set relative humidity 20% -45% (error range at each control set relative humidity is ± 5%), more preferably After conditioning for about 24 hours under constant temperature and humidity conditions maintained at 30 to 40%, more preferably 35%, the weight concentration is measured with a precision balance.

JP 2007-147437 A

  However, the technique described in Patent Document 1 has the following problems. That is, since the apparatus described in Patent Document 1 heats and drys sample air for weight measurement by a heater unit, the suspended particulate matter is heated, and volatile components (moisture content of moisture) contained in the suspended particulate matter are heated. In addition, other volatile components such as ammonia) are volatilized, and there is a problem that the measurement result by the apparatus and the measurement result by the manual analysis are greatly deviated.

  The present invention has been made in view of such circumstances, and when dehumidifying sample air used for measuring the weight of suspended particulate matter, the suspended particulate matter itself is dried without heating, and volatile components other than moisture are present. An object of the present invention is to provide an apparatus for measuring suspended particulate matter that can suppress volatilization of liquid (not shifting the equilibrium) and an apparatus for storing suspended particulate matter used in the measuring apparatus.

The first invention is
Collecting the microparticles among the suspended particulate matter in the atmosphere consisting of microparticles having a particle size of a predetermined value or less and coarse particles having a particle size exceeding the predetermined value, A device for measuring mass,
Classifying means for aspirating the sample atmosphere containing the suspended particulate matter, removing the coarse particles from the aspirated sample atmosphere, and obtaining microparticle-containing air containing the microparticles;
Drying means for dehumidifying the fine particles in the mixed air without heating by mixing the fine particle-containing air with dry air from which the suspended particulate matter has been removed in a mixer to generate mixed air;
A collecting means for guiding the mixed air to a first filter and collecting the fine particles on the first filter;
A suspended particulate matter measuring device comprising: a weight measuring unit that measures the weight of the fine particles collected on the first filter.

  According to the first aspect of the invention, the air containing fine particles is mixed with dry air from which suspended particulate matter has been removed to generate mixed air. Therefore, the suspended particulate matter is conditioned by heating the air around the suspended particulate matter (dehumidified air) without heating the suspended particulate matter. Therefore, volatilization of volatile components other than moisture in the microparticles can be suppressed (balance is not shifted), and the microparticles in which volatile components other than moisture are not volatilized can be subjected to weight measurement.

According to a second invention, in the first invention,
Humidity control means for controlling the humidity of the mixed air within a predetermined range is further provided.

  According to the second aspect, the humidity of the mixed air can be controlled within a predetermined range.

According to a third invention, in the second invention,
The humidity control means is
Including atmospheric measuring means for measuring humidity, temperature, and pressure of the atmosphere before being sucked into the mixer,
The humidity of the mixed air is feedback-controlled within the predetermined range based on the humidity, temperature, and pressure measured by the atmospheric measurement means.

  According to the third invention, the humidity of the mixed air can be accurately controlled based on the humidity, temperature, and pressure of the atmosphere before being sucked into the mixer.

According to a fourth invention, in the second invention,
The humidity control means is
Atmospheric measurement means for measuring the humidity, temperature, and pressure of the atmosphere before being sucked into the classification means;
Flow rate control means for feedback controlling the amount of the dry air mixed with the fine particle-containing air based on the humidity and temperature measured by the atmospheric measurement means so that the humidity of the mixed air is within the predetermined range. It is characterized by including.

  According to the fourth invention, the humidity of the mixed air can be accurately controlled based on the humidity, temperature, and pressure of the atmosphere before being sucked by the classifying means.

According to a fifth invention, in the second invention,
The humidity control means is
Dehumidified air condition measuring means for measuring the humidity, temperature, and pressure of the mixed air immediately before or immediately after the fine particles are collected on the first filter,
The humidity of the mixed air is feedback-controlled within the predetermined range based on the humidity, temperature, and pressure measured by the dehumidified air state measuring means.

  According to the fifth invention, since the humidity and temperature of the mixed air immediately before or immediately after the microparticles are collected on the filter are measured, the humidity and temperature of the mixed air immediately before or after the weight measurement is measured. Can do. Therefore, the humidity of the mixed air can be controlled more accurately.

A sixth invention is the second invention, wherein:
The humidity control means is
Dehumidified air condition measuring means for measuring the humidity, temperature, and pressure of the mixed air immediately before or immediately after the fine particles are collected on the first filter;
Based on the humidity, temperature, and pressure measured by the mixed air measuring means, the amount of the dry air mixed with the fine particle-containing air is feedback controlled so that the humidity of the mixed air is within the predetermined range. And a flow rate control means.

  According to the sixth invention, since the humidity and temperature of the mixed air immediately before or immediately after the microparticles are collected on the filter are measured, the humidity and temperature of the mixed air immediately before or after the weight measurement is measured. Can do. Therefore, the humidity of the mixed air can be controlled more accurately.

According to a seventh invention, in the first invention,
A second drying means for further dehumidifying the mixed air after the fine particles are collected on the first filter;
The dry air is air after the second drying means has been subjected to the mixed air after the fine particles have been collected on the filter.

  According to the seventh invention, the mixed air after the microparticles are collected can be changed to dry air and reused.

In an eighth aspect based on the first aspect,
The weight measuring means is a weight measuring means of β-ray absorption method.

  According to the eighth invention, it is possible to continuously measure the weight of the fine particles every arbitrary time. The time interval for performing the weight measurement is not particularly limited, but can be set to 1 second or 1 minute, for example.

According to a ninth invention, in the first invention,
The first filter is a tape filter,
The suspended particulate matter measuring device
A tape feeding mechanism for feeding the first filter in the length direction at a predetermined timing;
The tape feeding mechanism is
A first feed reel that supplies the unused first filter;
And a take-up reel for storing the used first filter in a roll shape.

  According to the ninth aspect, the tape-shaped first filter can be sent in the length direction at a predetermined timing, and the fine particles can be continuously collected on the first filter.

A tenth invention is the ninth invention,
A second feed reel for supplying a cover tape so as to be in close contact with the surface of the first filter on which the fine particles are collected;
The take-up reel is characterized in that the first filter and the cover tape are taken up together in a state where the first filter and the cover tape sandwich the fine particles.

  According to the tenth aspect of the invention, the tape filter and the cover tape can be wound up with fine particles sandwiched between the tape filter and the cover tape. Thereby, the microparticles collected on the tape filter can be stored.

In an eleventh aspect based on the first aspect,
The collection means collects the microparticles in the same time zone as the weight measurement method using filter sampling and a precision balance.

  According to the eleventh aspect, since the fine particles are collected in the same time zone as the weight measurement method using the filter sampling and the precision balance, the weight measurement can be performed under conditions close to the weight measurement method using the filter sampling and the precision balance. .

The twelfth invention
A suspended particulate matter storage device for storing collected suspended particulate matter,
A tape-like filter for collecting the suspended particulate matter;
A cover tape for protecting the suspended particulate matter collected by the tape filter;
A tape feeding mechanism for feeding the tape filter and the cover tape in the length direction,
The tape feeding mechanism is
A first feed reel for supplying the unused tape-shaped filter;
A second feed reel for supplying the cover tape so as to be in close contact with the surface on which the suspended particulate matter is collected in the tape-like filter;
The used tape-shaped filter and the cover tape include a take-up reel that accommodates the tape-shaped filter and the cover tape wound together in a roll shape with the suspended particulate matter sandwiched therebetween. The suspended particulate matter storage device.

  According to the twelfth aspect, the tape-shaped filter and the cover tape can be wound up in a state where the suspended particulate matter is sandwiched between the tape-shaped filter and the cover tape. Thereby, the suspended particulate matter collected on the tape-like filter can be stored. The suspended particulate matter may be either fine particles, coarse particles, or both.

  According to the present invention, when dehumidifying air used for weight measurement of suspended particulate matter, measurement of suspended particulate matter capable of suppressing volatilization of volatile components other than moisture in the suspended particulate matter (without shifting the equilibrium). An apparatus and a suspended particulate matter storage device used in the measurement apparatus can be provided.

The figure which shows the measuring apparatus of the suspended particulate matter which concerns on 1st Embodiment. Sectional view showing an example of a mixer The flowchart which shows operation | movement of the measuring apparatus shown in FIG. The figure which shows the measuring apparatus of the suspended particulate matter which concerns on 2nd Embodiment The figure which shows the measuring apparatus of the suspended particulate matter which concerns on 3rd Embodiment The figure which shows the measuring apparatus of the suspended particulate matter which concerns on 4th Embodiment The figure which shows the measuring apparatus of the suspended particulate matter which concerns on 5th Embodiment The flowchart which shows operation | movement of the measuring apparatus shown in FIG. The figure which shows the measuring apparatus of the suspended particulate matter which concerns on 7th Embodiment The figure which shows the change of the weight of the particulate matter collected by the filter The figure which shows the change of humidity at the time of the weight measurement of particulate matter A plot of ambient humidity and the humidity near the filter as absolute humidity

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an apparatus for measuring suspended particulate matter according to the first embodiment.

  The suspended particulate matter measuring device 1 according to the first embodiment includes the above-described suspended particulate matter in the atmosphere, which includes fine particles having a particle size equal to or smaller than a predetermined value and coarse particles having a particle size exceeding the predetermined value. It is an apparatus that collects fine particles and measures the mass of the collected fine particles. The predetermined value serving as the boundary between the fine particles and the coarse particles is not particularly limited, but is, for example, 2.5 μm.

  The suspended particulate matter measuring apparatus 1 (hereinafter sometimes referred to as the measuring apparatus 1) includes a classification means 2, a drying means 3, a collecting means 4, a weight measuring means 5, and a humidity control means 11. ing.

  The classifying means 2 sucks the sample atmosphere containing suspended particulate matter, and the aerodynamic particle size of the particles so that the classified particulate matter (mass standard) is 50% of the suspended particulate matter in the sucked sample atmosphere 6. Is used as a threshold value and classified into fine particles having a particle size equal to or smaller than the threshold value and coarse particles having a particle size exceeding the threshold value. Although the said threshold value is not specifically limited, For example, it shall be 2.5 micrometers. The type of the classification means 2 is not particularly limited. For example, when an impactor or a cyclone is used as the classification means, most of the coarse particles are removed from the sample atmosphere by inertial collision. The air 7 containing fine particles is removed. In addition, when the virtual impactor is adopted, the classifying means 2 classifies the coarse particle-containing air containing particles exceeding the above threshold at a ratio (mass ratio) of 50% or more by classification ratio and particles below the above threshold. The air is divided into fine particle-containing air 7 containing at a ratio (mass ratio) of 50% or more. Thereby, the classification means 2 can classify the suspended particulate matter contained in the air sucked by the sample inlet 27. The suction force in the classification means 2 is generated by a sample collection suction pump 25 provided downstream of the collection means 4.

  The drying means 3 generates the mixed air 9 by mixing the air 7 containing fine particles with the dry air 8 from which the suspended particulate matter is removed and generated by the non-heating drying process by the mixer 45. The fine particles inside are dehumidified without heating. In the example shown in FIG. 1, the drying means 3 includes a second filter 14, a dryer suction pump 15, a dryer 16, and a mixer 17. By mixing the dry air 8 with the fine particle-containing air 7, the humidity of the mixed air 9 becomes lower than the humidity of the fine particle-containing air 7, and dehumidification is performed. The type of the dryer 16 is not particularly limited as long as it is a non-heating type dryer. For example, the dryer 16 may have a structure in which a dehumidifying material such as silica gel is enclosed in a cylindrical container (column). In addition, the molecular sieves are packed in two columns, air drying is performed in one column, the molecular sieves are dried and regenerated in the other column, and the air drying column is alternately switched by controlling the valve. A self-regenerating dehumidifier called a heatless dryer that continuously performs air drying (dehumidification) can also be adopted.

  The second filter 14 is a filter that removes substantially all suspended particulate matter. The dryer suction pump 15 is a power source that sends the atmosphere to the second filter 14, sends the clean air from the second filter 14 to the dryer 16, and sends the dry air 8 from the dryer 16 to the mixer 17. is there. The mixer 17 mixes the fine particle-containing air 7 and the dry air 8. Although the structure of the mixer 17 is not specifically limited, For example, a T-shaped tube may be sufficient. Alternatively, the mixer 17 may be as shown in FIG. FIG. 2 is a cross-sectional view showing an example of the mixer 17. The mixer 17 shown in FIG. 2 includes an inverted conical portion 45 and a cylindrical portion 46 connected to the large diameter side of the inverted conical portion 45. A pipe 47 for introducing the dry air 8 is connected to the side surface of the cylindrical portion 46. On the central axis of the mixer 17, in the vicinity of the boundary between the cylindrical portion 46 and the inverted conical portion 45, an opening on one end side of the conduit 46 for introducing the sample atmosphere 7 is located. A pipe 49 that guides the mixed air 9 to the collecting means 4 is connected to the small diameter side of the inverted conical portion 45. The dry air 8 introduced from the pipe 47 and the sample atmosphere 7 introduced from the pipe 48 are uniformly mixed in the inverted conical portion 45. The mixed air 9 is guided to the collecting means 4 through the pipe line 49.

The collecting means 4 guides the mixed air 9 to the first filter 10 and collects the fine particles on the first filter 10. In the example shown in FIG. 1, the first filter 10 is a tape-like filter. The first filter 10 is preferably composed of a material that does not affect the mass analysis of the collected fine particles, and is composed of, for example, a tape-like fluorine membrane filter. The collecting means 4 includes a first filter 10 and a tape feeding mechanism 18 that sends the first filter 10 in the length direction at a predetermined timing. Although the timing which sends the 1st filter 10 is not specifically limited, For example, every 1 minute or every 1 hour can be used.
The tape feed mechanism 18 includes a first feed reel 19 that supplies an unused first filter 10 and a take-up reel 20 that winds and stores the used first filter 10 in a roll shape.
The collection means 4 preferably collects fine particles in the same time zone as the weight measurement method (manual analysis method) using filter sampling and a precision balance.

  The weight measuring means 5 measures the weight of the fine particles collected on the first filter 10. Although the kind of weight measuring means is not particularly limited, for example, a conventionally known β-ray absorption method can be employed.

  The collection position of the first filter 10 is irradiated with β-rays from a β-ray source, and the transmitted β dose is continuously detected, for example, every minute. The detection result is input to the CPU 28.

The relationship between the detection result of the β-ray detector (scintillation counter) and the amount of suspended particulate matter on the first filter 10 is calculated by Equation 1.
I _j = I _j-1 exp (−μΧ) (Χ: chi) (Equation 1)

Here, I _j is the β dose transmitted through the first filter 10 that has collected the microparticles at a certain moment, and I _j-1 is the same amount one minute before that. μ is a proportionality constant, and Χ is the amount of collected fine particles per unit area of the filter (mg / cm ² ). μ is a value inherent to the β-ray source, and is determined in advance in units of cm ² / mg by a standard substance.
Equation 1 is transformed to obtain Equation 2.
Χ = −ln (I _j / I _j−1 ) / μ (Expression 2)

By calculating the ratio of I _j to I _j-1 from equation 2, for example, the amount of fine particles per unit area of the filter collected per minute can be calculated, and if this is multiplied by the area of the collection position The amount of fine particles collected per minute (mg / min) can be calculated. Furthermore, by dividing the calculated amount of fine particles (mg / min) by the suction flow rate (m ³ / min), the mass concentration (mg / m ³ ) of the fine particles in the atmosphere can be obtained.

  In this way, the mass of the fine particles can be measured by the β-ray absorption method.

  The humidity control means 11 controls the humidity of the mixed air 9 within a predetermined range. The “predetermined range” here is not particularly limited, but is a value set by conditioning by the FRM method, for example, relative humidity of 20% to 45%, more preferably 30 to 40%, and still more preferably. Is 35%. In the example shown in FIG. 1, the humidity control unit 11 includes an air measurement unit 12, a mixed air measurement unit 29, and a flow rate control unit 13.

  The atmospheric measurement unit 12 measures the relative humidity, temperature, and pressure of the atmospheric air before being sucked into the classification unit 2. That is, the relative humidity, temperature, and pressure (atmospheric pressure) of the atmosphere outside the measuring apparatus 1 are measured.

  The mixed air measuring means 29 measures the temperature and pressure of the mixed air 9.

  Based on the humidity, temperature, and pressure measured by the atmospheric measurement unit 12, the flow rate control unit 13 mixes the dry air 8 mixed with the fine particle-containing air 7 so that the humidity of the mixed air 9 falls within the predetermined range. The amount of feedback is controlled. In the example shown in FIG. 1, the flow rate control means 13 includes a CPU 28, a flow rate sensor 21, an electromagnetic valve 22, a flow rate sensor 23, and an electromagnetic valve 24. The flow sensor 21 measures the flow rate of the air supplied to the dryer 16. The electromagnetic valve 22 adjusts the flow rate of air supplied to the dryer 16. The flow sensor 23 measures the flow rate of the mixed air 9 after the weight of the fine particles is measured by the weight measuring unit 5. The electromagnetic valve 24 adjusts the flow rate of the mixed air 9 after the weight of the fine particles is measured by the weight measuring means 5. The mixed air 9 is discharged into the atmosphere via the third filter 26 after the weight of the fine particles is measured by the weight measuring means 5. The third filter 26 removes substantially all suspended particulate matter contained in the mixed air 9.

  Next, operation | movement of the measuring apparatus 1 is demonstrated, referring the flowchart of FIG. FIG. 3 is a diagram showing the flow of air taken into the measuring apparatus 1 and the flow of signals. Solid arrows indicate air flow, and broken arrows indicate signal flow.

  First, the sample atmosphere is sucked from the sample inlet 27 (step S1). Next, the classifying means 2 classifies the sucked sample air into fine particle-containing air 7 and coarse particle-containing air (not shown) (step S2). Next, the mixer 17 mixes the dry air 8 with the fine particle-containing air 7 to generate the mixed air 9 (steps S3 and S4). Next, the collecting means 4 collects microparticles on the first filter 10 (step S5). Next, the weight measuring means 5 measures the weight of the fine particles by the β-ray absorption method (step S6). Next, the mixed air 9 whose weight has been measured is measured for temperature and pressure by the mixed air measuring means 29 (step S7). Next, in the mixed air 9 whose weight has been measured, the remaining suspended particulate matter is removed by the third filter 26 (step S8). Next, the flow rate of the mixed air 9 from which all the suspended particulate matter has been removed is controlled by the electromagnetic valve 24, and the flow rate is detected by the flow rate sensor 23 (step S9). Next, the mixed air 9 whose flow rate has been detected is discharged out of the measuring device 1 via the suction pump 25 (step S10).

  A process of generating the dry air 8 will be described. First, the dryer suction pump 15 sucks air (step S11). Next, all the suspended particulate matter is removed from the sucked air by the second filter 14 to become clean air (step S12). The atmospheric measurement unit 12 measures the relative humidity, temperature, and pressure of the atmosphere (step S13). The CPU 28 performs a predetermined calculation based on the temperature and pressure measured in step S7 and the relative humidity, temperature, and pressure measured in step S13, and generates a control signal (step S14). After the step S12, the flow rate of clean air is controlled by the electromagnetic valve 22, and the flow rate is detected by the flow rate sensor 21 (step S15). The opening degree of the electromagnetic valve 22 is controlled based on the control signal generated in step S14. Next, the clean air whose flow rate is controlled by the electromagnetic valve 22 is dried by the dryer 16 without being heated by the dryer 16 (step S16). Next, the dry air is mixed with the fine particle-containing air 7 as described in step S3 above.

Here, the calculation performed by the CPU 28 in step S15 will be described.
For sample air 6, dry air 8, mixed air (at the start of control), mixed air (after control), mass flow rate V, absolute concentration c of water, relative humidity rh, temperature t, absolute pressure p The characters representing are shown in Table 1 below.

  In the measuring apparatus 1 shown in FIG. 1, the CPU 28 calculates the relative humidity of the mixed air 9 based on the humidity, temperature, and pressure of the atmosphere outside the measuring apparatus 1 and the temperature and pressure of the mixed air 9. The humidity control of the air 9 is performed. Under the instruction of the CPU 28, the flow rate v1 of the sample atmosphere is fixed and the flow rate v2 of the dry air 8 is adjusted, whereby the relative humidity of the mixed air 9 is controlled to a predetermined value. This will be described below.

The absolute concentration of moisture in the sample atmosphere 6 is expressed by the following Equation 3.
c1 = f1 (rh1, t1, p1) (Formula 3)
The mass flow rate of the mixed air 9 (at the start of control) is expressed by Equation 4 below.
v3 = v1 + v2 (Formula 4)
The absolute concentration of moisture in the mixed air 9 (at the start of control) is expressed by the following formula 5.
c3 = (c1 × v1 + c2 × v2) / v3 (Formula 5)
If the amount of water in the dry air 8 is sufficiently small,
When c1 >> c2, c1 × v1 >> c2 × v2 is established, and Equation 3 can be transformed into Equation 6 below.
c3 = (c1 × v1) / (v1 + v2) (Formula 6)
The relative humidity of the mixed air 9 (at the start of control) is expressed by Equation 7 below.
rh3 = f2 (c3, t3, p3) (Expression 7)
By substituting c3 obtained in Equation 6 and measured t3 and p3 into Equation 7, the relative humidity rh3 of the mixed air 9 (at the start of control) is obtained. Therefore, the flow rate v2 may be adjusted so that rh3 becomes the target rh3 ′.
The above is the operation of the measuring apparatus 1.

  As described above, according to the measuring apparatus 1, since the mixed air 9 is generated by mixing the fine particle-containing air 7 with the dry air 8 from which suspended particulate matter has been removed, the humidity can be obtained without using a heating means. Can be generated (dehumidified air). Accordingly, the fine particles can be dehumidified without heating. This suppresses the volatilization of volatile components (a volatile component such as ammonia other than moisture) contained in the microparticles (does not shift the equilibrium), and provides the microparticles where the volatile components other than moisture do not volatilize for weight measurement. it can.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing an apparatus for measuring suspended particulate matter according to the second embodiment. In addition, about the structure similar to 1st Embodiment, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  In the suspended particulate matter measurement device 30 according to the second embodiment, an atmospheric measurement unit 31 and a mixed air measurement unit 32 are provided in place of the atmospheric measurement unit 12 and the mixed air measurement unit 29 in the first embodiment, respectively. Yes. In the second embodiment, the calculation performed by the CPU 28 is different from that in the first embodiment. Other configurations are the same as those of the first embodiment.

  The air measuring means 31 measures the temperature and pressure of the air before being sucked by the classifying means 2. That is, the temperature and pressure of the atmosphere outside the measuring device 1 are measured, and the humidity is not measured.

  The mixed air measuring means 29 measures the relative humidity, temperature, and pressure of the mixed air 9.

  The calculation of the CPU 28 performed in the second embodiment will be described below.

  In the measuring device 30 shown in FIG. 4, the CPU 28 calculates the relative humidity of the mixed air 9 based on the temperature and pressure of the atmosphere outside the measuring device 30 and the relative humidity, temperature and pressure of the mixed air 9, and mixes them. The humidity control of the air 9 is performed. Under the instruction of the CPU 28, the flow rate v1 of the sample atmosphere is fixed and the flow rate v2 of the dry air 8 is adjusted, whereby the relative humidity of the mixed air 9 is controlled to a predetermined value. This will be described below.

The mass flow rate of the mixed air 9 (at the start of control) is expressed by the following formula 8.
v3 = v1 + v2 (Formula 8)
The absolute concentration of moisture in the mixed air 9 (at the start of control) is expressed by the following formula 9.
c3 = (c1 × v1 + c2 × v2) / v3 (Equation 9)
If the amount of water in the dry air 8 is sufficiently small,
When c1 >> c2, c1 × v1 >> c2 × v2 is established, and Expression 9 can be transformed into Expression 10 below.
c1 = c3 × (v1 + c2) / v1 (Equation 10)
The relative humidity of the sample atmosphere is expressed by Equation 11 below.
rh1 = f2 (c1, t1, p1) (Equation 11)
By substituting c1 obtained by Equation 10 and measured t1 and p1 into Equation 11, the relative humidity rh1 of the sample atmosphere 6 is obtained.
By substituting the relative humidity rh1 and the measured t3 and p3 into Equation 3 described above, c1 is obtained. Thereafter, as in the first embodiment, the relative humidity rh3 is obtained by performing calculations using Equations 4-7. Therefore, the flow rate v2 may be adjusted so that rh3 becomes the target rh3 ′.

  According to the measuring device 30, since the mixed air 9 is generated by mixing the fine particle-containing air 7 with the dry air 8 from which suspended particulate matter has been removed, the air (dehumidified) is used without using heating means. Air). Accordingly, the fine particles can be dehumidified without heating. Thereby, volatilization of volatile components other than moisture contained in the microparticles can be suppressed (balance is not shifted), and the microparticles where volatile components other than moisture are not volatilized can be subjected to weight measurement.

(Third embodiment)
A third embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a diagram showing an apparatus for measuring suspended particulate matter according to the third embodiment. In addition, about the structure similar to 1st Embodiment, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  In the suspended particulate matter measuring device 33 according to the third embodiment, a mixed air measuring means 32 is provided instead of the mixed air measuring means 29 in the first embodiment. In the third embodiment, the calculation performed by the CPU 28 is different from that in the first embodiment. Other configurations are the same as those of the first embodiment.

  The mixed air measuring means 32 measures the relative humidity, temperature, and pressure of the mixed air 9.

  The calculation of the CPU 28 performed in the third embodiment will be described below.

  In the measurement device 33 shown in FIG. 5, the CPU 28 determines the absolute moisture content in the dry air 8 based on the relative humidity, temperature and pressure of the atmosphere outside the measurement device 33 and the relative humidity, temperature and pressure of the mixed air 9. The concentration is calculated, the flow rate of the dry air 8 is adjusted, and the humidity of the mixed air 9 is controlled. Under the instruction of the CPU 28, the flow rate v1 of the sample atmosphere is fixed and the flow rate v2 of the dry air 8 is adjusted, whereby the relative humidity of the mixed air 9 is controlled to a predetermined value. This will be described below.

The absolute concentration of moisture in the sample atmosphere 6 is expressed by the following formula 12.
c1 = f1 (rh1, t1, p1) (Formula 12)
The absolute concentration of moisture in the mixed air 9 (at the start of control) is expressed by the following formula 13.
c3 = f1 (rh3, t3, p3)
= (C1 * v1 + c2 * v2) / v3 (Formula 13)
The mass flow rate of the mixed air 9 (at the start of control) is expressed by the following formula 14 (same as formula 4).
v3 = v1 + v2 (Formula 14)
The relative humidity of the mixed air 9 (at the start of control) is expressed by the following formula 15 (same as formula 6).
rh3 = f2 (c3, t3, p3) (Equation 15)
If Equation 11 is modified and c2 is obtained, Equation 16 is obtained.
c2 = (c3 × v3−c1 × v1) / v2 (Expression 16)
By substituting Equation 13 for c3 in Equation 15, c2 and v2 are obtained so that rh3 becomes the target rh3 ′, and the flow rate of the dry air 8 may be adjusted to the value of v2.

  According to the measuring device 33, the air containing the fine particles containing air 7 is mixed with the dry air 8 from which suspended particulate matter has been removed to produce the mixed air 9, so that the air (dehumidification) is reduced without using heating means. Air). Accordingly, the fine particles can be dehumidified without heating. Thereby, volatilization of volatile components other than moisture contained in the microparticles can be suppressed (balance is not shifted), and the microparticles where volatile components other than moisture are not volatilized can be subjected to weight measurement.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a diagram showing an apparatus for measuring suspended particulate matter according to the fourth embodiment. In addition, about the structure similar to 3rd Embodiment, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  The suspended particulate matter measuring device 39 according to the fourth embodiment is different from the third embodiment in that the weight measurement is not performed, but the mixed air 9 having been subjected to the weight measurement is not exhausted to the outside as in the third embodiment. This is the point that the finished mixed air 9 is dried again and then returned to the mixer 17. Details will be described below.

  In 4th Embodiment, as FIG. 6 shows, the 2nd filter 34, the 2nd drying means 35, and the flow control means 36 are provided.

  The second filter 34 further removes suspended particulate matter from the mixed air 9 after the fine particles are collected on the first filter 10.

  The second drying means 35 performs further dehumidification on the mixed air 9 after the fine particles are collected on the first filter 10.

  The flow rate control means 36 controls the humidity, temperature, and pressure measured by the atmospheric measurement means 12 and the mixed air 9 measured by the mixed air measurement means 29 so that the humidity of the mixed air 9 falls within the predetermined range. Based on the humidity, temperature, and pressure, the amount of the dry air 8 mixed with the fine particle-containing air 7 is feedback-controlled. In the example shown in FIG. 6, the flow rate control means 36 includes a CPU 28, a flow rate sensor 38, an electromagnetic valve 37, a flow rate sensor 23, and an electromagnetic valve 24. The flow sensor 38 measures the flow rate of the air supplied to the dryer 16. The electromagnetic valve 37 adjusts the flow rate of air supplied to the dryer 16. A part of the mixed air 9 is returned to the mixer 17 after filtering and drying, and the remaining air passes through the third filter 26 after the weight of the fine particles is measured by the weight measuring means 5. And discharged into the atmosphere.

  Therefore, the dry air 8 supplied to the mixer 17 is processed by the second filter 34 and the second drying means 35 with respect to the mixed air 9 after the fine particles are collected on the first filter 10. It is the air after it was made. That is, the mixed air 9 that has passed through the weight measuring means 5 is subjected to filter processing and drying processing (drying processing without heating), whereby the mixed air is changed to dry air and reused.

  According to the measuring device 39, since the mixed air 9 is changed to dry air and reused, waste of energy used for drying can be saved.

(Fifth embodiment)
A fifth embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a diagram showing an apparatus for measuring suspended particulate matter according to the fifth embodiment. In addition, about the structure similar to 4th Embodiment, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  The suspended particulate matter measuring device 40 according to the fifth embodiment is different from the fourth embodiment in that a dryer 41 is provided in place of the dryer 16, and the flow rate sensor 23 is connected to the dryer 41, so that the sample is captured. The collection suction pump 25 is connected to the dryer 41, and other configurations are the same as those of the fourth embodiment. The mixed air 9 whose weight has been measured is dried again by the dryer 41 and then returned to the mixer 17. This will be described in detail below.

  The dryer 41 is a double cylinder structure including an inner cylinder and an outer cylinder. One end of the inner cylinder is connected to the dryer suction pump 15, and the other end is connected to the mixer 17. The inner cylinder is composed of a semipermeable membrane dehumidifying material. For this reason, when the inner atmospheric pressure is higher than the outer atmospheric pressure, the inner cylinder absorbs moisture of the air flowing inside and releases the absorbed moisture to the outside. The type of the semipermeable membrane dehumidifying material is not particularly limited. For example, a Nafion (registered trademark) tube manufactured by Perm Pure Corporation can be used. The Nafion® tube is composed of a polymer of tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid. A flow sensor 23 is connected to a side surface of one end of the outer cylinder, and a sample collection suction pump 25 is connected to a side surface of the other end. With this structure, moisture is absorbed from relatively high pressure air flowing through the inner cylinder, and the moisture is discharged from the sample collection suction pump 25. Therefore, the dryer 41 can generate dry air 8 from which moisture has been further removed from the mixed air 9.

  Next, the operation of the measuring apparatus 40 will be described with reference to the flowchart of FIG. FIG. 8 is a diagram showing the flow of air taken into the measuring device 40 and the flow of signals. Solid arrows indicate air flow, and broken arrows indicate signal flow.

First, the sample atmosphere is sucked from the sample inlet 27 (step S1). Next, the classifying means 2 classifies the sucked sample air into fine particle-containing air 7 and coarse particle-containing air (not shown) (step S2). Next, the mixer 17 mixes the dry air 8 with the fine particle-containing air 7 to generate the mixed air 9 (steps S3 and S4). Next, the collecting means 4 collects microparticles on the first filter 10 (step S5). Next, the weight measuring means 5 measures the weight of the fine particles by the β-ray absorption method (step S6). Next, the mixed air 9 whose weight has been measured is measured for temperature and pressure by the mixed air measuring means 29 (step S7). The CPU 28 performs a predetermined calculation based on the temperature and pressure measured in step S7 and the relative humidity, temperature, and pressure measured in step S8, and generates a control signal (step S9). The mixed air 9 whose temperature and the like have been measured in step S7 is branched, one air is led to the second filter 34, and the other air is led to the third filter 26 (step S10). The mixed air 9 guided to the second filter 34 is cleaned of all suspended particulate matter by the second filter 34 and becomes clean air (step S11). Next, the flow rate of clean air is controlled by the electromagnetic valve 22, and the flow rate is detected by the flow sensor 21 (step S12). Clean air is sucked by the dryer pump 15 (step S13) and guided into the inner cylinder of the dryer 41 (step S14). The mixed air 9 introduced to the third filter 26 in step S10 is cleaned by removing all suspended particulate matter by the third filter 26 (step S15). Next, the flow rate of clean air is controlled by the electromagnetic valve 24, and the flow rate is detected by the flow rate sensor 23 (step S16). Clean air is guided between the outer cylinder and the inner cylinder of the dryer 41 (step S17). The clean air guided between the outer cylinder and the inner cylinder is sucked by the sample collection suction pump 25 and discharged to the outside (step S16). In steps S14 and S17, the clean air flowing through the inner cylinder is dehumidified without being heated to dry air. The dry air is mixed with the fine particle-containing air 7 in step S3.
The operation of the measuring device 40 has been described above.

  According to the measuring apparatus 40, the air-containing particulate matter 7 is mixed with the dry air 8 generated by the non-heated drying process after the suspended particulate matter is removed, so that the mixed air 9 is generated. Without this, air (dehumidified air) in which the humidity of the air around the suspended particulate matter is reduced can be generated. Therefore, volatilization of volatile components other than moisture in the microparticles can be suppressed (balance is not shifted), and the microparticles where volatile components other than moisture are not volatilized can be subjected to weight measurement.

(Sixth embodiment)
A sixth embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a diagram showing an apparatus for measuring suspended particulate matter according to the sixth embodiment. In addition, about the structure similar to 5th Embodiment, the same referential mark is attached | subjected and the description is abbreviate | omitted.

  The difference between the suspended particulate matter measuring device 42 according to the sixth embodiment and the fifth embodiment is that the fine particles collected on the first filter 10 can be stored.

  The measuring device 42 includes a second feed reel 43. The second feed reel 43 supplies the cover tape 44 so as to be in close contact with the surface of the first filter 10 on which the fine particles are collected.

  The take-up reel 20 winds the first filter 10 and the cover tape 44 together with the first filter 10 and the cover tape 44 sandwiching fine particles. The first filter 10 and the cover tape 44 are formed to have the same band width, for example. The type of the cover tape 44 is not particularly limited, but is formed of a material that hardly changes the components of the fine particles.

  According to the measuring device 42, the first filter 10 and the cover tape 44 are wound together with the first filter 10 and the cover tape 44 sandwiching the fine particles, whereby the fine particles after the weight measurement are stored. be able to. The stored microparticles can be subjected to composition analysis and the like.

(Other embodiments)
In each of the above embodiments, the mixed air 9 having the target relative humidity is obtained by calculation using the above equations. However, the flow rate v2 of the dry air 8 is changed by trial and error, and the mixed air is obtained. The relative humidity of 9 may converge to the target relative humidity.

Next, the effect of the present invention will be described with reference to FIGS.
FIGS. 10-12 is a figure which shows the time series data at the time of measuring the suspended particulate matter in air | atmosphere from 12:00 of noon to 11:00 of the following day.

  FIG. 10 shows the change in the weight of the particulate matter collected by the filter. The measurement was performed with the apparatus with the humidity control function according to the present invention, and at the same time, the comparative measurement was performed with the apparatus without the humidity control function. Furthermore, it compared with the measured value by the manual analysis method conventionally performed using the sampler.

  Referring to FIG. 10, it can be seen that the device (A) with a humidity control function is finally close to the weight value (marked by ●) by the manual analysis method, and the weight fluctuation is small. On the other hand, the apparatus (B) which did not perform humidity control had a large fluctuation, and the weight increased especially at night, and the tendency that the weight hardly changed from dawn to noon was apparent. This is because the particulate matter collected by the filter absorbs moisture in the atmosphere at night when the temperature decreases and the humidity increases, and conversely at night when the temperature increases and the humidity decreases. It is considered that the weight largely fluctuates because the water accumulated in the water is released. This can be clearly seen from the change in humidity during measurement (see FIG. 11).

  FIG. 12 is a plot of the humidity of the outside air and the humidity in the vicinity of the filter as absolute humidity, and it can be seen that the humidity is kept low by mixing dry air by humidity control.

  As described above, the automatic measuring instrument replaces the conventional manual analysis method by controlling the humidity and keeping the humidity low to measure the affected particulate matter continuously while suppressing the influence of humidity in the sample atmosphere. It is considered to be an effective means for developing

  In addition, since the measurement apparatus according to the present invention performs humidity control without heating the air sample, it is also an apparatus that can perform measurement without excessive loss of volatile components other than water.

  INDUSTRIAL APPLICABILITY The present invention can be used as a continuous measurement device for fine suspended particulate matter having a great influence on human health.

1, 30, 33, 39, 40, 42 Airborne particulate matter measuring device 2 Analyzing means 3 Drying means 4 Collecting means 5 Weight measuring means 6 Sample atmosphere 7 Fine particle-containing air 8 Dry air 9 Mixed air 10 First filter DESCRIPTION OF SYMBOLS 11 Humidity control means 12, 31 Atmospheric measurement means 13, 36 Flow control means 14, 34 2nd filter 15 Suction pump for dryers 16, 41 Dryer 17 Mixer 18 Tape feed mechanism 19 First feed reel 20 Take-up reel 21 , 23, 38 Flow rate sensor 22, 24, 37 Solenoid valve 25 Sample collection suction pump 26 Third filter 27 Sample inlet 28 CPU
29, 32 Mixed air measuring means 35 Second drying means 43 Second feed reel 44 Cover tape 45 Reverse conical part 46 Cylindrical part 47, 48, 49 Pipe line

Claims (12)

Collecting the microparticles among the suspended particulate matter in the atmosphere, consisting of microparticles having a particle size of a predetermined value or less and coarse particles having a particle size exceeding the predetermined value, A device for measuring mass,
A classifying means for aspirating the sample atmosphere containing the suspended particulate matter, removing the coarse particles from the aspirated sample atmosphere, and obtaining microparticle-containing air containing the microparticles;
The fine particles in the mixed air are removed by mixing the fine particle-containing air with dry air generated by non-heating drying treatment from which the suspended particulate matter has been removed to produce mixed air. Drying means for dehumidification by heating;
A collecting means for guiding the mixed air to a first filter and collecting the fine particles on the first filter;
A suspended particulate matter measuring device comprising: a weight measuring unit that measures the weight of the fine particles collected on the first filter.   The suspended particulate matter measuring device according to claim 1, further comprising humidity control means for controlling the humidity of the mixed air within a predetermined range. The humidity control means includes
Air measurement means for measuring the humidity, temperature, and pressure of the atmosphere before being sucked into the mixer;
The suspended particulate matter measuring device according to claim 2, wherein the humidity of the mixed air is feedback controlled within the predetermined range based on the humidity, temperature, and pressure measured by the atmospheric measuring means. The humidity control means includes
Atmospheric measurement means for measuring humidity, temperature, and pressure of the atmosphere before being sucked into the classification means;
Flow rate control means for feedback-controlling the amount of the dry air mixed with the fine particle-containing air based on the humidity and temperature measured by the atmospheric measurement means so that the humidity of the mixed air is within the predetermined range. The suspended particulate matter measuring device according to claim 2, wherein: The humidity control means includes
Dehumidified air condition measuring means for measuring the humidity, temperature, and pressure of the mixed air immediately before or immediately after the fine particles are collected on the first filter;
The suspended particulate matter measurement according to claim 2, wherein the humidity of the mixed air is feedback-controlled within the predetermined range based on the humidity, temperature, and pressure measured by the dehumidified air state measuring means. apparatus. The humidity control means includes
A mixed air measuring means for measuring the humidity, temperature, and pressure of the mixed air immediately before or immediately after the fine particles are collected on the first filter;
Based on the humidity, temperature, and pressure measured by the mixed air measuring means, the amount of the dry air mixed with the fine particle-containing air is feedback controlled so that the humidity of the mixed air is within the predetermined range. The suspended particulate matter measuring device according to claim 2, further comprising: a flow rate control unit that performs the control. A second drying means for further dehumidifying the mixed air after the fine particles are collected on the filter;
The said dry air is air after the process by the said 2nd drying means was made | formed with respect to the said mixed air after the said microparticles | fine-particles were collected on the said 1st filter, It is characterized by the above-mentioned. Item 1. The suspended particulate matter measuring device according to Item 1.   2. The suspended particulate matter measuring device according to claim 1, wherein the weight measuring unit is a β-ray absorption weight measuring unit. The first filter is a tape filter;
The suspended particulate matter measuring device is
A tape feeding mechanism for feeding the first filter in the length direction at a predetermined timing;
The tape feeding mechanism is
A first feed reel for supplying the unused first filter;
The suspended particulate matter measuring device according to claim 1, further comprising a take-up reel that winds and stores the used first filter in a roll shape. A second feed reel for supplying a cover tape so as to be in close contact with the surface on which the fine particles are collected in the first filter;
The float according to claim 9, wherein the take-up reel winds the first filter and the cover tape together in a state where the first filter and the cover tape sandwich the fine particles. Particulate matter measuring device.   2. The suspended particulate matter measuring apparatus according to claim 1, wherein the collecting means collects the fine particles in the same time zone as a weight measurement method using filter sampling and a precision balance. A suspended particulate matter storage device for storing collected suspended particulate matter,
A tape-like filter for collecting the suspended particulate matter;
A cover tape for protecting the suspended particulate matter collected by the tape filter;
A tape feeding mechanism for feeding the tape filter and the cover tape in the length direction,
The tape feeding mechanism is
A first feed reel for supplying the unused tape-like filter;
A second feed reel for supplying the cover tape so as to be in close contact with the surface on which the suspended particulate matter is collected in the tape-like filter;
The used tape-shaped filter and the cover tape include a take-up reel that accommodates the tape-shaped filter and the cover tape wound together in a roll shape with the suspended particulate matter sandwiched therebetween. Suspended particulate matter storage device.

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