JP2001343319A - Continuous measuring device for suspended particulate matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device of continuously, automatically, individually measur ing, every constant time, each of the total amount TPS of suspended particulate matters and micro suspended particulate matter PM2.5 having 2.5 μm grain size especially damaging human health. SOLUTION: A classifier 2 classifies air into an air containing all coarse suspended particulate matters CP having grain size exceeding 2.5 μm and an air containing only PM2.5. The classified air are sucked through first and second positions 3a and 3b of a tape-like filter 3, and thus the suspended particulate matters in the classified airs are collected in the first and second positions 3a and 3b of the filter 3, and quantitatively determined individually. The amounts of the PM2.5 and the TPS are calculated based on classifying efficiencies of the classifier 2, and contents of the PM2.5 and the TPS are calculated based on the amount and the integration value of the permeated air amount and recorded on a recorder 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates 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 having a particle size of 2.5 μm or less, which has a great effect on human health.

[0002]

2. Description of the Related Art Suspended particulate matter having various particle sizes exists in the atmosphere. Suspended particulate matter having a particle size of more than 10 μm is likely to settle near the source, and during respiration, most of it is filtered through the respiratory tract, except when working in a dusty environment. There is no major harm to human health. For these reasons, the environmental standards for air pollution based on the Basic Law on Pollution Control say that airborne particulate matter
The particle size is specified to be 10 μm or less. And
Conventionally, measuring devices for suspended particulate matter having a particle size of 10 μm or less have been commercially available in accordance with this regulation.

Recently, the relationship between the particle size and the content of suspended particulate matter in an urban area was examined in detail, and as shown in FIG. 7, as shown in FIG. coarse particle (hereinafter abbreviated as CP) and fine suspended particulate matter (FP)
Has been found to exist in the atmosphere. The majority of CP is dust from sea salt particles and soil, and is considered to occur naturally. In contrast, F
P is considered to occur artificially and is common in urban areas.
In particular, exhaust from diesel vehicles contains a large amount of FP as elemental carbon. Further, it is considered that a substance harmful to health, such as nitrogen oxides and sulfur oxides in the air, is adsorbed to elemental carbon. According to recent medical and epidemiological studies, it has been reported that the presence of about 20 μg / m ^{3 of} FP causes myocardial infarction.

[0004] In order to reduce FP in urban areas, the Tokyo Metropolitan Government has a policy to obligate the installation of filters in diesel vehicles, and it is presumed that other local governments will follow this. There is a demand for the development of a device that automatically and continuously measures the temperature.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to continuously and automatically measure the total amount of suspended particulate matter having a particle size of 10 μm or less and the amount of FP that is harmful to human health. It is to provide a device that does.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a sample air at a constant flow rate is sucked, and air containing all of the large suspended particulate matter having a particle diameter of more than 2.5 μm and air containing no large suspended particulate matter are included. Classification means for classifying suspended particulate matter into air containing only fine suspended particulate matter having a particle diameter of 2.5 μm or less, and coarse suspended particulate matter classified by the classification means via different positions of a tape-shaped filter Air containing all of the substance and air containing only the fine suspended particulate matter are separately suctioned, and the collecting means for continuously collecting the classified suspended particulate matter separately, and the collecting means Detecting means for continuously detecting the amount of suspended particulate matter collected at different positions of the tape-shaped filter, and an output of the detecting means,
Calculating the amount of all suspended particulate matter in the atmosphere and the amount of fine suspended particulate matter in the atmosphere from the integrated value of the suctioned atmospheric flow rate and calculating and automatically recording the suspended particulate matter. It is a continuous measurement device for particulate matter.

According to the present invention, the sucked atmosphere is CP
And air containing only FP,
Suspended particulate matter contained in each air is continuously collected separately at different positions of the tape-shaped filter, and the collected suspended particulate matter is continuously detected separately, and this is taken along with the suctioned air flow rate. From this, the total amount of suspended particulate matter in the atmosphere and the amount of FP are calculated and automatically recorded.

[0008] The classification means used in the present invention is not particularly limited, but may be a virtual impactor (vi) described later.
A classifier called a rtual impactor is preferably used.

Further, in the present invention, the detection means is a detector based on the β-ray absorption method, and the weight of the total suspended particulate matter and the weight of the fine suspended particulate matter in the air are respectively determined at regular intervals. It is characterized by continuous detection.

According to the present invention, the detector is of the β-ray absorption type. In the β-ray absorption method, the mass of the suspended particulate matter can be individually detected from the increase in the amount of absorption of β-rays by the suspended particulate matter collected on the filter. The substance serving as the radiation source of the β-ray irradiation is not particularly limited, but the radiation handling qualification and notification are not required, and 3.7 MBq (100 μC
It is preferred to use the ¹⁴⁷ _Pm sealed source of i).

According to the present invention, a sample air at a constant flow rate is sucked through a tape filter, airborne particulate matter in the air is collected on the filter, and the collected floating particulate matter is collected by a β-ray absorption method. A continuous measurement device for detecting with a detector, wherein the tape-shaped filter is a fluorine-based membrane filter, and is a continuous measurement device for suspended particulate matter.

According to the present invention, a tape-like fluorine-based membrane filter is used as a filtering material. 2. Description of the Related Art A glass fiber filter is used as a filtering material of a conventional suspended particulate matter measuring device. A glass fiber filter has a relatively large pore size, and particles having a particle size of 1 μm or less may be transmitted. On the other hand, the fluorine-based membrane filter has a small pore size and can collect particles having a particle size of about 0.2 μm. In addition, compared to glass fiber filters, fluorine membrane filters are easier to manufacture homogeneously,
When in a tape shape, there is little variation at each collection position.

Further, according to the present invention, a sample air at a constant flow rate is sucked through a tape-shaped filter, and airborne particulate matter in the air is continuously collected on the tape-shaped filter. The substance is continuously detected by a β-ray absorption type detector, and the collected suspended particulate matter is irradiated with white light, and the amount of elemental carbon in the suspended particulate matter is continuously determined from the intensity of the scattered light. This is a continuous measurement apparatus for suspended particulate matter, which is characterized in that the particulate matter is continuously detected.

According to the present invention, a β-ray absorption method and a light scattering method of irradiating a detector with white light and detecting the intensity of scattered light are used. The β-ray absorption method described above is used,
Suspended particulate matter is detected. The filter capturing the suspended particulate matter is irradiated with white light, and the amount of elemental carbon in the suspended particulate matter is detected from the intensity of the scattered light. This method is effectively used because elemental carbon is black and there is almost no other black suspended particulate matter. The suspended particulate matter includes the whole amount or CP or FP, particularly FP, classified by the classification means.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments.

FIG. 1 is a block diagram showing a configuration of an apparatus 1 for continuous measurement of suspended particulate matter according to one embodiment of the present invention. The sample air sucked into the apparatus 1 is air containing all of the CP by the virtual impactor classifier 2 and FP
Classified into air containing only FP, and air containing only FP,
It is filtered by the tape-shaped fluorine-based membrane filter 3 at the first position 3a, and is exhausted to the outside through the first flow rate sensor 4, the first pressure sensor 5, the first suction pump 6, and the first silencer 7. The output of the first flow sensor 4 is a CPU
13 so that the first input flow rate is
Outside air is sucked from the first flow regulator 8. On the other hand, the air containing all of the CP classified by the classifier 2 is filtered by the second position 3b of the filter 3 and the second flow sensor 1
4. The air is exhausted to the outside through the second pressure sensor 15, the second suction pump 16, and the second silencer 17. The flow rate of the second flow rate sensor 14 is set to a predetermined second flow rate.
8, the same adjustment is performed. As a result, the FP and the CP that are continuously classified are separately captured at the first position 3a and the second position 3b of the filter 3, respectively.

The first position 3a and the second position 3b of the filter 3 are irradiated with β-rays from the first β-ray source 9 and the second β-ray source 19, and the transmitted β dose is continuously changed, for example, every minute. Is detected. The detection result is the first preamplifier 11
And input to the CPU 13 through the second preamplifier 21. The light source 23 is located at the first position 3a of the filter 3.
Is irradiated with white light having a constant intensity through the optical fiber 24, and the reflected light is transmitted through the optical fiber 24 to the photodetector 25.
, And the detection result is input to the CPU 13 via the third preamplifier 26.

When air is continuously transmitted to the first and second positions 3a and 3b of the filter 3, the amount of the suspended particulates collected on the first and second positions 3a and 3b is reduced. The filter 3 is fed by the tape feed mechanism 27 in the direction of the arrow 28 by a certain length C at regular time intervals, for example, every hour, because
FIG. 2 is a plan view showing the vicinity of the first position 3a and the second position 3b of the filter 3, at which the next measurement is started. The first position 3a and the second position 3b of the filter 3 for collecting suspended particulate matter are, for example, circular with a diameter of 11 mm. The filter 3 is supplied in a tape shape and wound around a supply roll 29, and is supplied to a first position 3a and a second position 3b by a plurality of guide rollers (not shown). It is wound on a winding roller 30 via a tape feed mechanism 27 composed of two upper and lower rollers. The tape feed mechanism 27 feeds the filter 3 by a certain length C in the direction of the arrow 28 after a certain time has elapsed. As a result, the position of 3a 'of the new filter 3 moves to 3a, and the position of 3b' moves to 3b.

The relationship between the detection results of the first and second β-ray detectors 10 and 20 and the photodetector 25 and the amount of suspended particulate matter on the filter is calculated by Equation 1. I _j = I _j−1 exp (−μx) (1)

Here, I _j is the β dose transmitted through the filter that traps suspended particulate matter at a certain moment or the amount of light reflected by the filter, and I _j−1 is the same amount one minute before. . I ₀ is the β dose transmitted through a new filter before trapping suspended particulate matter or the amount of light reflected by the filter, μ is a proportionality constant, and x is the trapping per unit area of the filter. Amount of suspended particulate matter (mg / cm
² ). μ is a value specific to the β-ray source and the light source,
It is determined in advance in the unit of cm ² / mg by the standard substance. Modification of Equation I gives Equation 2.

[0021]

(Equation 1)

By calculating the ratio between I _j and I _j-1 from Equation 2, for example, the amount of suspended particulate matter per unit area of the filter collected in one minute can be calculated.
(Which is equal to the area of the second position, which is about 0.95 cm ² for a diameter of 11 mm), the amount of suspended particulate matter collected in one minute (mg / m
in) can be calculated.

Next, the configuration of the virtual impactor classifier 2 used in the present embodiment and the amount of air passing through the first position 3a and the second position 3b of the filter 3 will be described. FIG. 3 is a cross-sectional view for explaining the configuration of the virtual impactor classifier 2. The virtual impactor classifier 2 includes a nozzle unit 40, an air collecting unit 45, and an outer tube unit 5.
0. The nozzle part 40 gushes air,
A circular jet port 41 having an inner diameter D ₀ , a cylindrical portion 42 connected to the jet port 41 and having a length T, and a constricted tube portion 43 connected to the cylindrical portion 42, and air is smoothly jetted from the jet port 41. You. Gas collector portion 45 is surrounded by a cylindrical partition wall 46 having the same axis and the axis of the nozzle portion 41, and a larger inner diameter D ₁ than the D _0, length and the tip of the spout 41 and the partition wall 46 They face each other at intervals of S. The outer tube portion 50 is surrounded by an outer tube 51 having an inner diameter sufficiently larger than the partition wall 46,
It has a discharge port 52 shown in FIG. The discharge port 52 and the air collecting section 45 are connected to the first and second suction pumps 6 and 16, and the air Q ₀ jetted from the jet port 41 is changed to Q ₁ and (Q
_0- Q ₁ ). When the air ejected from the ejection port 41 is ejected at a linear velocity (20,000 to 25,000 m / min) corresponding to about 10,000 Reynold nozzles, the fine particles 60 in the air flow along the streamline. The outer tube 50 (main stream) and the air collecting unit 4 are arranged in accordance with the flow rate of the air.
5 (secondary flow). On the other hand, coarse particles 61
Almost all enter the secondary flow due to their inertia. Be determined the _{D 1 / D 0, S /} D 0, T / D 0, Q 1 / Q 0 appropriately, it is possible to obtain the classifier 2 almost all the CP enters the secondary flow. D ₀ = 3.912 mm, D ₁ / D ₀ =
1.28, S / D ₀ = 1.0, T / D ₀ = 2.0, Q ₀ =
27.7l / min, driving a virtual impactor classifier 2 under the condition of Q ₁ / Q ₀ = 0.10, particle size 1-10
The air containing μm suspended particulate matter was classified. FIG. 4 shows the results. As shown in FIG. 4, when the virtual impactor classifier 2 is operated under the above conditions, the classification is not completely performed with the particle size of 2.5 μm. They meet at a position of 2.5 μm, and are roughly classified with a particle size of 2.5 μm. In order for the classification to be performed accurately, the first and second flow sensors 4 and 14 use the classifier 2
The main flow and the secondary flow are monitored by the first and second flow regulators 8 and 18 so that they become predetermined amounts, that is, (Q ₀ -Q ₁ ) and Q _1. .

The amount of suspended particulate matter actually calculated is:
FP total amount to air amount Q ₀ (hereinafter, referred to as PM2.5 amount), elemental carbon content in the FP (hereinafter PM2.5C amount hereinafter) and total suspended particulate matter amount (hereinafter, referred to as TPS weight), and From the FP amount, FPC amount (elemental carbon amount in FP) and CP amount calculated previously, the following equation 3
Is calculated. _{PM2.5 = Q 0 / (Q 0} -Q 1) × FP PM2.5C = Q 0 / (Q 0 -Q 1) × FPC ... (3) TPS = FP + CF

PM2.5, PM2.5C, TP in air
In order to calculate the content of S in the air, it is necessary to convert the amount of air Q ₀ flowing in one minute to a reference state, for example, 0 ° C. and 1 atm. For this purpose, the first and second flow sensors 4, 1
The pressure is measured by the first and second pressure sensors 5 and 15 provided after the pressure sensor 4, and the temperature is measured by the temperature sensor 31. The measured values of the first and second flow sensors 4 and 14 are set to the reference state every minute. It is converted to flow rate. These calculations are C
The calculation is performed by the operation unit of the PU 13, and the result is recorded in the recorder 32.

FIG. 5 illustrates the operation of the CPU 13.
It is a flowchart of FIG. For operation of the tape feed mechanism 27
Therefore, the first and second positions 3a, 3b of the filter 3
A new filter surface comes and starts at step S0
You. In step S1, j = 0 is set, and in step S2
I₀Is detected. First and second suction in step S3
The pumps 6 and 16 are operated and the first and second flow sensors
The output of 4,14 is (Q ₀−Q₁) Is Q₁First to be
And the flow rate is adjusted by the second flow rate adjusters 8 and 18. Stay
In step S4, j = j + 1 is set, and in step S5, j + 1 =
It is determined whether it is 60 or not, and if this is denied, the step
Go to S6, I_{j + 1}Is detected. In step S7, I_{j + 1}
/ I_jIs calculated, and in step S8, the performance described above is performed.
Calculation of PM2.5, PM2.5C and TPS
In step S9, the calculation result is recorded in the recorder 32.
Then, the process returns to step S4. J + 1 = 60 in step S5
, That is, if one hour has elapsed, the process proceeds to step S10.
Steps 1 and 2 of the first and second suction pumps are stopped.
A series of measurements ends in S11. Tape feed mechanism 27
Activate to start the next measurement.

FIG. 6 is a graph showing an example of the result of continuous measurement of airborne particulate matter in the air for two days using the apparatus for continuously measuring floating particulate matter 1 shown in FIG. In the actual measurement results, the total suspended particulate matter TPS is recorded. However, it is difficult to see many portions overlapping the curve representing the amount of fine suspended particulate matter. Expressed as the amount of particulate matter.

[0028]

As described above, according to the present invention, the classifier classifies the air containing all of the CP and the air containing only the FP without containing the CP, and each air is continuously filtered into a tape filter. Is sucked through different positions. As a result, the amount of suspended particulate matter collected at different positions on the tape-shaped filter is continuously and automatically measured, and based on this and the integrated value of the amount of air transmitted through the filter, the amount of suspended particulate matter in the atmosphere is determined. , And the content of the fine suspended particulate matter are continuously and automatically recorded separately. Thereby, it is possible to continuously and automatically measure the minute suspended particulate matter which affects human health.

Further, the measurement of minute suspended particulate matter is performed by the β-ray absorption method and the light scattering method, which greatly affects human health, and the amount of elemental carbon which is considered to be the main emission source by diesel vehicles is continuously measured. Can be measured automatically.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus 1 for continuous measurement of suspended particulate matter according to an embodiment of the present invention.

FIG. 2 is a plan view showing the vicinity of a collection position (a first position 3a and a second position 3b) of a tape-shaped fluorine-based membrane filter 3.

FIG. 3 is a cross-sectional view of the virtual impactor classifier 2.

FIG. 4 is a graph showing an example of classification by the virtual impactor classifier 2.

FIG. 5 is a flowchart for explaining the operation of the CPU 15;

FIG. 6 is an example of a display of a recorder when the suspended particulate matter in the air is measured using the present apparatus 1.

FIG. 7 is a graph showing a particle size distribution of suspended particulate matter in air in an urban area.

[Explanation of symbols]

 Reference Signs List 1 Suspended particulate matter measuring device 2 Virtual impactor classifier 3 Tape-like fluorine membrane filter 3a First position 3b Second position 4,14 Flow sensor 5,15 Pressure sensor 6,16 Suction pump 8,18 Flow controller 9, 19 β-ray source 10, 20 β-ray detector 13 CPU 23 White light source 24 Glass fiber 25 Photodetector 27 Tape feed mechanism 31 Temperature sensor 32 Recorder

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G01N 15/06 G01N 15/06 C (72) Inventor Keiji Soedama 3-1, Funabashi-cho, Tennoji-ku, Osaka-shi, Osaka No. Kimoto Electronics Co., Ltd. F-term (reference) 4D021 FA14 FA15 GA02 GA03 GA12 GA27 GA29 GB10 HA10 4D058 JA24 JB14 JB23 KD10 NA01 PA03 QA01 QA06 SA20 UA25

Claims (4)

[Claims] 1. A sample air having a constant flow rate is suctioned, and air containing all of the large suspended particulate matter having a particle diameter of more than 2.5 μm, and air having a particle diameter of 2.5 μm containing no large suspended particulate matter are included.
Classification means for classifying suspended particulate matter into the following air containing only small suspended particulate matter, and air containing all of the large suspended particulate matter classified by the classification means through different positions of the tape filter Collecting means for sucking air containing only minute suspended particulate matter separately and continuously collecting the classified suspended particulate matter, and different positions of the tape-shaped filter by the collecting means. Detecting means for continuously detecting the amount of suspended particulate matter trapped in the air, the output of the detecting means, and the integrated value of the suctioned atmospheric flow rate, the amount of all suspended particulate matter in the atmosphere, And a calculation recording means for calculating and automatically recording the amount of the suspended particulate matter, and a continuous measurement apparatus for the suspended particulate matter. 2. The method according to claim 1, wherein the detecting means is a detector based on a β-ray absorption method, and detects the weight of all suspended particulate matter and the weight of fine suspended particulate matter in the atmosphere. The continuous measurement apparatus for suspended particulate matter according to claim 1. 3. A sample air at a constant flow rate is sucked through a tape filter, airborne particulate matter in the air is collected on the filter, and the collected airborne particulate matter is detected by a β-ray absorption type detector. A continuous measurement device for suspended particulate matter, wherein the tape-shaped filter is a fluorine-based membrane filter. 4. A sample air at a constant flow rate is suctioned through a tape-shaped filter, and airborne particulate matter in the air is continuously collected on the tape-shaped filter. Continuous detection with a line-absorption detector, irradiates the collected suspended particulate matter with white light, and continuously detects the amount of elemental carbon in the suspended particulate matter from the intensity of the scattered light. A continuous measuring apparatus for suspended particulate matter.