JPH11264796A - Dust quantity measuring device and measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the quantities of dusts differed in physical property, generating range, and generating quantity by arranging a separated laser projector and receiver opposite to each other, determining the transmittance of the laser beam, and calculating the dust quantity by use of a linear regression expression showing the relation between its logarithmic conversion value and the dust quantity. SOLUTION: A laser projector 1 and a laser receiver 6 are arranged opposite with a dust generation source as the center, and a projecting light 5 is arranged so as to separate from about 1 m from the generating source in order to prevent the adhesion to an optical window or lens. Prior to dust quantity measurement, a calibrator 14 is arranged on the optical axis, a dust sample having a known weight is added, and the transmissivity of the laser beam is calculated by a signal processing part 17 to determine a linear regression expression showing the relation between its logarithmic conversion value and the dust quantity. The natural linear regression expression corresponding to the property of the dust generating source to be measured and the physical property of the dust is determined by this calibration and stored. In an actual measurement, the offset value of the environment to be measured is determined by the linear regression expression of a selected target to be measured, and the linear regression line natural, to the dust generation source to be measured is formed to determine the dust quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for measuring a dust amount based on an attenuation of a laser beam.

[0002]

2. Description of the Related Art Although a dust concentration measuring device using an attenuation of a laser beam is known, generally, a distance between a light emitting device and a light receiving device,
Dust gas is led to, for example, a duct so that the width of the dust-containing gas (hereinafter, abbreviated as dust gas) during this period is also constant, and a laser projector and a light receiver are arranged on this wall surface. An integrated product fixed at a predetermined dimensional interval is disposed in a dust gas, a correlation between a light receiving level and a dust concentration for dust having predetermined physical properties is determined, and measurement is performed under these conditions ( Known example 1). Also,
A dust meter for measuring dust in a long-distance space where the dust gas width is not always constant is disclosed in Japanese Utility Model Laid-Open Publication No. 60-76255 (known example 2). It comprises a projector for projecting a laser beam, and a receiver for receiving the laser beam, which is provided opposite to the projector, and measures the dust concentration from the attenuation of the laser beam. The relationship between the dust concentration and the output of the light receiver is determined in advance so as to have an exponential relationship, and based on this is measured as the average dust concentration in the space between the light emitter and the light receiver.

[0003]

In the improvement of the environment in, for example, a foundry having various dust sources, first, the total weight of the dust actually generated for each dust source (hereinafter, referred to as the total weight)
It is necessary to measure the amount of dust. To do this,
The amount of dust must be able to be measured according to the physical properties of the dust (e.g., particle material, particle size, cohesiveness, light attenuating property, etc.) specific to each dust generation source and the generation range and capacity of dust gas.
Conventionally, there is no known technique capable of directly measuring the total amount of generated dust, and there is a problem described below even when the measurement is indirectly performed based on the dust concentration. In the dust concentration measurement device in the above-mentioned known example 1, for a dust generation source such as a melting furnace, for example, a duct is difficult to install at the top, and furthermore, since the light emitter and the light receiver directly come into contact with high-temperature or corrosive gas. Not applicable due to problems in equipment reliability and durability.
Further, the laser dust meter in the known example 2 obtains an averaged dust concentration in the space between the measuring instruments, and cannot obtain the concentration in the generated dust gas when the dust gas generation range is different. That is, even if the dust concentration is the same, the output of the light receiver changes depending on the transmission distance in the dust gas, and also changes depending on the distance between the light receiver and the dust generation source. In addition, none of the known examples discloses a method for obtaining a correlation between the dust concentration and the output of the light receiver in accordance with the physical properties of the dust. Therefore, the present invention provides a dust amount measuring apparatus and a measuring method capable of measuring the amount of generated dust, even for dust having different physical properties, and also for those having different generation ranges and amounts of dust gas. It is intended to be.

[0004]

According to the present invention, there is provided a dust amount measuring apparatus comprising: a laser projector for projecting a laser beam; a laser receiver for receiving the projection light separated from the laser projector; the laser projector and a laser receiver; A control unit that is electrically connected to calculate the logarithmic conversion value of the transmittance of the laser beam, calculates the amount of dust based on the set logarithmic conversion value and the amount of dust, and calculates the amount of dust based on the amount of generated dust gas. It is characterized by having a calibrator for obtaining a linear regression equation representing a relational expression between the conversion value and the amount of dust. The calibrator is used at the time of a calibration operation for obtaining a constant indicating the slope of a linear regression equation specific to the measurement object prior to the measurement of the amount of dust, and is capable of filling and diffusing dust inside the medium. Both end portions are light-transmitting cylinders, and have a cross-sectional dimension that allows laser projection light to pass through the cylinder along the axis. As the medium, a liquid that can transmit laser light, for example, water, alcohol, and various other solvents can be used in that the dust can be diffused uniformly, but the interface can be used so that the dust is diffused uniformly. It is preferable to add an activator or use a liquid having a slightly higher viscosity than water. Further, the present invention is characterized in that a dust gas generation amount is obtained based on a dust gas generation width measuring means and a dust gas moving speed measuring means, and an absolute dust amount at predetermined time intervals is calculated as a dust amount. Here, the dust gas generation width means an angle component of the length of the dust gas passage of the laser projection light that is substantially orthogonal to the moving direction of the dust gas. It is desirable that the amount of generated dust gas is actually measured at each sampling time by using the above-mentioned means, but it may be set in a numerical value based on a measured value or the like obtained from a measurement object in advance.

A method for measuring the amount of dust according to the present invention is to obtain a logarithmic conversion value of transmittance based on the intensity of light projected from a laser projector and the intensity of incident light from a laser receiver receiving the projected light, and perform a calibration operation in advance. Calculate the calibration reference dust amount from the relational expression between the logarithmic conversion value and the dust amount specific to the dust amount measurement object obtained based on
The invention is characterized in that the length of dust gas passage of the laser projection light and the amount of dust gas generated are measured to correct the dust amount of the calibration standard, and the actually generated dust amount is calculated. Calibration operation, every time a dust sample of a known weight is mixed with a calibrator of a predetermined length having a medium of known capacity, the laser light is projected from the laser projector from the axial center direction and the incident light is irradiated by the laser receiver. Then, a logarithmic conversion value of the laser transmittance with respect to the dust amount at this time is collected, a linear regression equation is obtained from this, and a constant indicating the slope thereof is obtained.

[0006]

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIGS. The dust amount measuring device includes a laser projector 1, a laser receiver 6, a signal processor 1
7, an input / output unit 20, a calibrator 14, and a dust gas amount measuring means 36. The laser projector 1 uses a colored, for example, red semiconductor laser as the light source 2 and modulates it with the modulator 4 in order to suppress the influence of disturbance light. Further, in order to make the laser transmission cross-sectional area in the dust gas as uniform as possible at the time of measurement and to prevent the spread of the laser light, the collimator lens 3 is provided, and the laser light is emitted from the laser projector 1. The projection light 5 is configured to be parallel light having a circular cross section. The laser light receiver 6 detects the incident light 13 only within a certain angle with the light receiving lens 10 in order to reliably receive the incident light 13 which is the laser light transmitted through the dust atmosphere on the optical axis. A diaphragm 19 is provided. The light receiving element 12 uses a silicon photodiode.
An optical filter 11 such as an interference filter that selects and transmits only the wavelength of the light source 2 and an ND filter for suppressing the influence of disturbance light is provided on the front surface of the light receiving element 12.

When actually measuring the amount of dust at a site having a plurality of dust generating places, such as a foundry, a laser beam and a light receiver are set at a position corresponding to the dust generating source by circulating around each dust generating source. Must be measured. Therefore, it is necessary to align the optical axis of the laser projector 1 and the laser light receiver 6 each time it moves, and the laser light receiver 6 is provided with an optical axis extending portion so that the optical axis can be easily adjusted. This is because a part of the incident light 13 is reflected at a right angle and the derived light 15
And a magnifying lens for magnifying the derived light 15, a cross screen for centering, and a filter 8 for attenuating the intensity to a level safe to the eyes. The light is projected on the optical axis opening window 9. While looking through the optical axis setting window 9, the center of the derived light 15 is adjusted to the intersection of the cross to set the optical axis.

The signal processing unit 17 includes a logarithmic operation unit 26 having a computer function, a dust amount operation unit 28, and a memory 2
7 and is electrically connected to the input / output unit 20. The logarithmic calculation unit 26 has a transmittance calculation unit 26a and a logarithmic conversion unit 26b. The transmittance calculating means 26a includes:
When the intensity I ₀ of the projection light 5 and the intensity I of the incident light 13 from the laser projector 1 and the laser receiver 6 are input as electric signals, the transmittance I / I ₀ is calculated. Logarithmic conversion means 26
b is a logarithmic conversion of the calculated transmittance I / I ₀ and outputs the logarithmically converted value X to the dust amount calculation unit 28,
Output to the input / output unit 20. The dust amount calculation unit 28 calculates a linear regression equation from data obtained by a calibration operation described later, and calculates the dust amount N. The input / output unit 20 includes a monitor 22
And an input terminal 29 for outputting various data to the outside, and a printer or an external storage device can be connected as needed.

The relationship between the dust amount N and the logarithmic conversion value X of the laser transmittance can be expressed by a linear regression equation N = aX + b as described later. a is a constant to be set for each measurement object,
b is a constant (offset value) determined by the measurement environment or the calibration conditions, and the value of the constant a must be obtained prior to the measurement of the amount of dust (hereinafter, an operation for this is referred to as a calibration operation). The calibrator 14 is used at the time of the calibration operation, and is a cylindrical body having optical windows 18 at both end surfaces through which a laser beam can pass, in which a dust sample is put. For example, a dust sample addition port 16 is provided on a cylindrical side surface of a transparent synthetic resin having an inner diameter d and a length h, transparent glass is set at both ends, and a structure such as a medium such as water can be sealed therein. A value is appropriately selected such that the dust sample injected in a predetermined amount has a capacity such that the dust sample injected therein does not agglomerate and diffuses sufficiently evenly with an inner diameter sufficient for the projection light to penetrate along the axis without hitting the side surface. . The laser projector 1 and the laser receiver 6 are separated from each other.
The calibrator 14 can be installed at an arbitrary position by using a tripod or an installation table 14a so that the calibrator 14 can be positioned on the laser optical axis.

Here, it will be described that the relationship between the dust amount N and the logarithmic conversion value X of the laser transmittance can be expressed by a linear regression equation N = aX + b. The transmittance I / I ₀ can be expressed by the following equation 1 based on Lambert-Beer's law and Mie theory.

(Equation 1) Where K: Optical transmission attenuation coefficient of the system At the time of on-site measurement: K = k1 (transmission attenuation coefficient of ambient air) At the time of calibration: K = K1 · K2 · exp ^{( -β , n, h)} K2 · exp ^{( -β , n, h)} : Calibrator total transmittance (K2: Calibrator transmission window and medium attenuation coefficient) β: Medium attenuation coefficient n: Medium molarity h: Calibrator length

(Equation 2) R (α, θ): distance between the dust source and the light receiver, and correction coefficient based on the average particle parameter α: average particle parameter (= π · D / λ (λ is the wavelength of the laser beam)) θ: Detection angle determined by the distance between receivers Q _ext : Dust attenuation coefficient (average) ρ: Dust particle density (average) D: Dust diameter (average) N ': Dust amount per unit length of laser passing through dust atmosphere L: Length of laser passing through the dust atmosphere (L = h at the time of calibration) Further, -X = ln (I / I0): (ln is a symbol indicating natural logarithm) N = N '· La = 1 / ｛ R (α, θ) · Q _ext · 3/2 · 1 / (ρ
D) ｂ b = a · ln K Equation 1 can be converted to the above-described linear regression equation N = aX + b.

Next, the procedure from the calibration operation to the on-site measurement of the amount of dust will be described with reference to FIG. Blocks S1 to S4
Is a calibration operation, which is an operation performed according to the properties of the dust source to be measured and the physical properties of the generated dust,
Especially when the situation is different in each case, it is necessary to do so. In block S1, the tripods 1a and 6 are arranged such that the laser projector 1 and the laser receiver 6 have the same positional relationship when the laser projector 1 and the laser receiver 6 are arranged with respect to the dust source to be actually measured.
a, and arranged facing each other. The distance to be separated depends on the properties of the dust source. The laser projector 1 and the laser receiver 6 may be damaged by contact with high-temperature or corrosive dust gas, or the dust may be damaged by the optical window or lens of the laser projector 1 or the laser receiver 6. Distance so that it does not adhere to The reason why the distance is the same at the time of calibration as at the time of actual measurement is to make the detection angles of the incident light received by the laser light receiver 6 the same.

Next, as shown in block S2, the optical axes of the laser projector 1 and the laser receiver 6 are set, and the signal output is checked. The optical axis alignment is performed by irradiating the projection light 5 from the laser projector 1, first adjusting the tripod 1 a of the projector 1 so that the above-mentioned derived light 15 enters the optical axis alignment window 9 of the laser receiver 6, and then While looking through the optical axis opening window 9, the tripod 6a of the laser receiver 6 is adjusted so that the center of the derived light 15 is aligned with the intersection of the cross. After completing the optical axis alignment, the mounting table 14a is positioned and set so that the calibrator 14 is arranged on the optical axis at a location corresponding to the actual position of the dust generation source. Next, the calibrator 14 is removed from the installation table 14a, and the projection light 5 from the laser projector 1 is directly applied to the laser receiver 6. At this time, it is checked whether or not the logarithmic conversion value of the transmittance is close to zero. This is because the incident light 13 received by the light receiving element 12 of the laser receiver 6 is reduced by the derived light 15 separated toward the optical axis opening window 9 and the signal processing unit 17 performs logarithmic conversion of the transmittance. In calculating the value X, this is corrected, but this is a function check.

Next, calibration data collection shown in S3 is performed.
First, a translucent medium whose volume v is accurately measured is put into the calibrator 14. The calibrator 14 containing the medium is set on the installation table again, and the medium is irradiated with laser light to transmit through the medium, and a logarithmic conversion value X0 of the transmittance at that time is obtained. At this time, the dust amount calculation unit 28 sets the dust amount N0 to 0. Of course,
At this time, the cross-sectional area occupied by the medium when the calibrator 14 is set needs to include the transmission cross section of the projection light 5. Next, of a plurality of additive samples prepared by accurately measuring the weight from the dust sample collected from the actual dust to be measured, first, an arbitrary sample having an arbitrary weight N1 is added to the calibrator 14, and the medium and After mixing well, a laser is projected to obtain a logarithmic conversion value X1 of the transmittance. At this time, the logarithmic conversion value of the transmittance may be measured, for example, every 0.1 seconds, and the peak value or an average value in the vicinity thereof may be determined as the logarithmic conversion value X1 from the measured value. This is because the particle size of the dust is usually as small as several to several tens of μm, but the specific gravity is often different from that of the medium, and the particles settle or float over time,
This is because the logarithmic conversion value of the measured transmittance changes with time. Thereafter, the dust-added sample is sequentially calibrated to Calibrator 1
4 and the same measurement was performed, and the logarithmic value X of the laser transmittance with respect to the weight N1, N2.
1, X2 ... is collected. The added weight data is input using a keyboard or the like of the input / output unit. As a medium to be put into the calibrator 14, a liquid that easily mixes uniformly with a minute amount of fine dust and has a good transmittance, for example, clear water may be used. Even if it is not necessarily a liquid, a gas can be used if a means capable of sufficiently agitating the dust sample, for example, a blow circulation means is provided.

Subsequently, as shown in block S4, a linear regression equation N = AX + B 'of the measurement object is calculated by the least square method based on the measurement data of the logarithmic conversion value Xi for the plurality of dust amounts Ni. It is stored in the memory 27. The constant value A is a unique value determined by the properties of the dust and the detection angle, whereas the constant value B 'is an offset value peculiar to calibration, and needs to be obtained again at the time of actual measurement. The above-described calibration operations in blocks S1 to S4 are performed in accordance with the properties of the dust generation source to be measured and the physical properties of the generated dust, and a unique linear regression equation corresponding to each is obtained and stored.
Here, the dust amount N calculated from the linear regression equation indicates the amount of dust contained in the medium having the volume v at the time of the dust passage length h under the calibration operation environment. The amount of dust during the measurement of the dust is determined by determining the specific constant value B, the length L of the laser passing through the dust gas, and the amount of dust gas generated (capacity).
It must be calculated by correcting for V.

The procedure after block S5 is the procedure for measuring the amount of dust from the actual dust source. First, the linear regression equation N = AX + B ′ of the measurement target is selected from the linear regression equation obtained by the above-described calibration operation and stored in the memory 27 for each measurement target. Next, in block S6, the laser projector 1
And the laser light receiver 6 are arranged with the same positional relationship as that arranged at the time of the calibration, with the measurement object interposed, and the optical axis is aligned. Next, as shown in block S7, a laser is projected when no dust is generated, and a logarithmic conversion value of the transmittance at this time is obtained. The dust amount calculator 28 sets the dust amount N to zero for the selected linear regression equation N = AX + B ′, thereby obtaining the offset value B of the measurement target environment in place of the offset value B ′ unique to the calibration. Then, a unique linear regression equation for the measurement target dust source, N = AX + B, is created.

In block S8, the measurement is started when the generation of dust starts. Every predetermined sampling time (for example, 0.1 second), the set unique linear regression equation N
= AX + B, the dust amount N is calculated. here,
As described above, this dust amount value N is based on the calibrator 14, and the width of the dust atmosphere through which the laser passes is h
Indicates the amount of dust contained in the volume v of the calibration note 14 based on the logarithmic conversion value of the transmittance at the time of the measurement, and differs from the amount of dust Y actually generated. Hereinafter, a method of calculating the actually generated dust amount Y will be described. The linear regression equation N = AX + B every predetermined sampling time after the start of measurement
And the amount of dust gas generated by the dust gas amount measuring means 36,
A dust gas generation width H spread in a direction substantially perpendicular to the moving direction is obtained. As these values, empirical values obtained in advance for each measurement object may be used, but the rising speed S of the dust gas 39 per unit time is measured using the anemometer 38 as the movement amount measuring means, and the dust gas generation The width measurement means can be obtained by photographing the movement of the dust gas 39 using an image pickup device such as a strobe camera or a video camera 37.

The dust gas generation width H is obtained as follows. When the projection light from the laser projector passes through the dust gas 39, the area through which the laser has passed becomes red and can be identified. Therefore, the captured image is transmitted to the image processing means (not shown), and a known By means of projection light 5
The length L that has passed through the dust gas 39 is determined. here,
When the laser projector and the light receiver are set so as to irradiate a laser beam in a direction orthogonal to the dust gas generation movement direction, the dust gas passage length L of the laser projection light is directly used as the dust gas generation width H. When the irradiation is set in a direction inclined by an angle γ from a direction orthogonal to the orthogonal direction, the cosine component Lcosγ is set to the dust gas generation width H. When the dust gas passage line of the laser projection light cannot be clearly distinguished due to a low dust concentration or the like, an assumed laser passage line is provided in the captured image, and the dust gas passage length L is determined based on the line. You can ask. When the rising speed S of the dust gas 39 is obtained by the anemometer 38, the movement amount per sampling interval time t can be calculated. These data are sent to the signal processing means 17, and for each sampling time, the generation amount V of the dust gas 39 per sampling interval time t is, for example, uniformly distributed in a circle whose diameter is the dust gas generation width H. Assuming that it is calculated by the following equation. ^{V = S × t × πH 2} /4

Based on the above measurement results, the signal processing unit calculates the amount of dust Y for each sampling time by the following equation. Y = N × h / L × V / v The calculated data is output to an external storage device,
The data can be output to a monitor of an input / output unit or a printer, so that a target dust source in the case of environmental improvement can be selected and the effect of improvement can be accurately evaluated. In addition, it can be used as appropriate, such as for equipment improvement. The total amount of generated dust can be obtained by integration, and the state of generation of dust over time can be obtained. Further, the dust concentration W can be obtained as shown by the following equation, and can be used when managing the dust concentration. In this case, for the dust from the dust generation source, the dust gas amount measuring means 3
The dust gas passage length L of the laser projection light is measured using only the video camera 37 out of 6. Further, for a dust floating atmosphere remote from a specific dust generation source, the distance between the laser projector 1 and the laser receiver 6 may be set to the dust gas passage length L without using the video camera 37. W = N × h / L × 1 / v

(Embodiment 2) Next, Embodiment 2 in which operation and handling are easier will be described with reference to FIG. Among the configurations described in the first embodiment,
The configuration of the control unit is mainly changed, and the signal processing unit 17 and the input / output unit 20 are integrated to form an operation panel 30. Therefore, the other same components are the same and the detailed description is omitted, and the same reference numerals are used in the description. The operation panel 30 according to the second embodiment has a configuration in which several switches and a simple display 31 such as a liquid crystal are provided on the surface as shown in FIG. In addition, it has an external output terminal and can be connected to external display means such as a printer. The control function is almost the same as that described in the first embodiment, and includes a logarithmic operation unit and a dust amount operation unit, but the control algorithm is formed by a hardware logic circuit.

The logarithmic calculation unit has a transmittance calculator and a logarithmic converter. The transmittance calculating means includes the laser projector 1
When the intensity I ₀ of the projection light 5 from the laser receiver 6 and the intensity I of the incident light are input as electric signals, the transmittance I /
I ₀ is obtained by a logic circuit, and this electric signal is sent to logarithmic conversion means. The logarithmic conversion means is provided with the transmittance I / I _0.
Is logarithmically converted by a logic circuit, and the logarithmically converted value X is output as an electric signal to the dust amount calculation unit. The dust amount calculation unit is
It has a logic circuit constituting the linear regression equation N = aX + b and finds the dust amount N. The logarithmic conversion value X and the dust amount N of the transmittance I / I ₀ are obtained at predetermined time intervals (for example, every 0.1 second),
It can be displayed on a display and output from an external output terminal. The display can be made by appropriately operating the changeover switch 32 to display one display 31.
, The logarithmic conversion value X, the dust amount N
May be provided with a unique indicator for Amplification rate adjusting means 33
Is a dial for setting a constant a to be set for each measurement target in the linear regression equation by a voltage, and is composed of a variable resistor with a scale. The offset adjusting means 34 is a dial for setting a constant b determined by a measurement environment or calibration conditions by a voltage, and is composed of a scaled variable resistor.

The calibration operation is basically the same as the above-described method, except that the method of setting the constants a and b is different from the procedure thereof. After the arrangement of the laser projector 1, the laser receiver 6, and the calibrator 14, the alignment of the optical axis, etc., are completed, the calibrator 14 is removed from the installation table 14a,
The projection light 5 from the laser projector 1 is directly applied to the laser receiver 6. At this time, the logarithmic conversion value X of the transmittance is displayed on the display 31 of the operation panel, and it is checked whether or not the value is close to zero. This is because the incident light 13 received by the light receiving element 12 of the light receiver 6 is reduced by the amount of the derived light 15 separated toward the optical axis opening window 9, and the logarithmic processing unit performs the logarithmic conversion value X of the transmittance. Is converted into a circuit to correct this, but this function is confirmed.

Next, calibration data is collected. As in the first embodiment, first, fresh water whose volume v has been accurately measured is put into the calibrator 14. The calibrator 14 containing the fresh water is set again on the installation table 14a, and is irradiated with a laser beam to transmit the clear water, and a logarithmic conversion value X0 of the transmittance at that time is obtained. Next, from the dust sample collected from the actual dust to be measured, among a plurality of additive samples prepared by accurately measuring the weight, first, an arbitrary sample having an arbitrary weight N1 is added to the calibrator 14 and the fresh water is added to the calibrator 14. After mixing well, a laser is projected and the logarithmic conversion value X1 of the transmittance is recorded. At this time, the measured value is output to a printer or the like every 0.1 seconds, and based on the output data, the peak value or an average value in the vicinity thereof is converted to a logarithmic conversion value X.
It is good to be 1. Thereafter, the added samples are sequentially calibrator 14
And the same measurement is performed, and the relationship between the logarithmic value Xi of the laser transmittance and the weight Ni of the sample added in the calibrator is collected. Subsequently, based on the collected data of Xi for the plurality of Nis, a linear regression equation N =
AX + B ′ is calculated by the least squares method, and a constant value A to be measured is obtained.

Next, prior to the actual measurement at the site, an operation of setting the values of the constants a and b of the linear regression equation in the environment to be measured from the operation panel 30 is performed. First, a laser is projected with the calibration container 14 removed, and the logarithmic conversion value Xair of the transmittance is obtained.
Is displayed on the display unit to obtain the value. Next, the display value Nair value of the dust amount at this time is displayed on a display, and the offset adjusting means 34 is adjusted so that this value becomes zero. This is an operation for obtaining an offset value in the measurement environment at the site, and corresponds to setting the value B of the constant b. Next, an ND filter having a predetermined attenuation rate (for example, 10%) is inserted in front of the laser receiver 6 to create a simulated dust transmission state, and a logarithmic conversion value Xn of the laser transmittance at this time is obtained. From this, based on the constants A and Xair values obtained above, the dust equivalent amount Nn at this time is obtained by calculation from the equation of Nn = A (Xn-Xair). With the ND filter inserted, the amount of dust is displayed, and the gain adjusting means 33 is adjusted so that the displayed value indicates the calculated value. At this time, the scale values of the amplification factor adjusting means 33 and the offset adjusting means 34 are recorded in a memo or the like. The above operation is performed for each dust source to be measured prior to the on-site measurement, and the constants a and b
Is equivalent to obtaining the values A and B for the unique environment for each target site. In the actual measurement, the constant values A and B of the linear regression equation specific to the measurement object are set to the amplification factor adjusting means 3.
3. The setting is performed by the offset adjusting means 34, and the linear regression equation in the dust amount calculation section is determined before the determination. Main operation panel 30
The above-mentioned operation is necessary because the device is created only by an electric circuit such as a logic circuit. However, since an input device such as a numeric keypad is not required, the device is compact and can be easily handled on site.

[0024]

EXAMPLE An example of measurement of the amount of dust generated from a melting furnace having a melting hole of 1 m in diameter based on Embodiment 2 will be described below with reference to FIGS. The laser projector 1 and the laser receiver 6 are separated from each other by 20 m with the melting furnace 40 at the center.
m was set so as to pass almost horizontally. This is because the high-temperature dust that rises almost vertically when the furnace lid of the melting furnace 40 is opened adheres to the optical window of the laser projector 1 or the laser receiver 6, which causes a change in laser intensity, that is, a decrease in reliability of measurement accuracy. This is to prevent the laser projector 1 and the laser receiver 6 from receiving the radiant heat of the molten metal near 1500 ° C. As the calibrator 14, the inner diameter d =
A sample having a size of 0.09 m and a length h of 0.5 m was used, and was filled with about 90% of the volume of fresh water. At this time, the capacity of the fresh water was v = 0.0029 m ³ . First of all,
The laser projector 1, the laser receiver 6, and the calibrator 14 were arranged in the same manner as in the actual measurement, and the calibrator 14 was irradiated with laser in a state of only fresh water without adding dust, and a logarithmic conversion value X0 of the laser transmittance was obtained. . Next, in order to calculate a linear regression equation, dust generated from the melting furnace 40 is collected, a dust sample whose weight N1 has been measured in advance is added, and the dust is shaken by hand to diffuse uniformly. The logarithmic conversion value of the laser transmittance with respect to was output to a printer or the like every 0.1 seconds, and the peak value was obtained as the logarithmic conversion value X1.

Here, in order to obtain the linear regression equation with high accuracy, a dust amount was added to the calibrator 14 so as to obtain a transmittance close to the actual dust generation state. This dust amount was set as follows. First, from the experience so far, the dust concentration above the melting furnace 40 is 2 g / m ³ or more.
It was about 10 g / m ³ , and it was found that the dust gas 39 spread in a width of about 1.5 m at a height of 1 m from the top of the melting furnace. From this, on the basis of this, the transmittance when the laser projection light 5 passes through the length h = 0.5 m of the calibrator 14 is made equal to that when the laser projection light 5 passes through the dust gas width 1.5 m described above. The amount of dust was determined. When the dust concentration above the melting furnace 40 is, for example, 2 g / m ³ , the corresponding amount of added dust was calculated as follows. 2 × 0.0029 × 1.5 / 0.5 = 0.0174 g From this, 5 sets of dust samples whose weights are accurately measured with approximately 17 mg register are prepared. The logarithmic value Xi of the transmittance was measured. In addition, when a small amount of surfactant was added to Shimizu,
The diffusion state of the dust was stable and good.

Subsequently, a linear regression equation N = AX + B ′ for estimating the amount of dust was obtained by the least square method from the data of the added dust weight Ni and the logarithmic value Xi of the measured laser transmittance. FIG. 5 shows the relationship between the amount of added dust Ni and the linear regression equation based on the logarithmic conversion value Xi of the laser transmittance. From this, the slope A of the linear regression equation 35a for estimating the amount of dust from the data of the dust generated from the melting furnace 40 is A = 6.
It was 7. The other linear regression equation 35b shown above in the same figure is for an automatic pouring machine obtained in the same manner. Next, prior to actual measurement at the site, an operation of setting values of constants A and B of a linear regression equation for estimating the amount of dust was performed. First, when measuring the amount of dust in the melting furnace 40, the logarithmic conversion value Xair of the laser transmittance was obtained with the calibration container 14 removed. At this time, the offset adjusting means 34 was adjusted so that the display 31 of the display value Nair value of the dust amount became 0. Next, a predetermined attenuation rate (for example, 10%)
Was inserted in front of the light receiver 6 to obtain a logarithmic conversion value Xn of the laser transmittance. With the ND filter inserted, the display value of the dust amount Nn is Nn = 67 (Xn-X
The amplification factor adjusting means 33 was adjusted to have a value obtained by the calculation formula of (air).

Next, the operation panel 30 calibrated as described above
The laser projector 1 and the laser receiver 6 are set at the above-mentioned predetermined positions with respect to the target melting furnace 40 by using
After the lid of No. 0 was opened, the measured dust amount N every 0.1 second was displayed on the display 31 and output to the printer. Here, the dust amount N is a reference for the calibration operation (capacity of a cylinder having an inner diameter of 0.09 m and a length of 0.5 m of 0.0029 mm).
(the amount of dust contained in m ³ ), and the actual amount of dust was determined as follows. First,
The movement of the dust gas 39 was imaged by the video camera 37. At the same time, the rising speed S of the dust gas was measured from the anemometer 38 installed above the melting furnace, and the value at the same time when the dust amount N was output was output to the printer. The dust gas passage length L of the laser projection light was calculated from the image of the red laser light in the image corresponding to the above-described measurement time, based on the image after imaging. Accordingly, the amount of dust gas generated in the sampling time interval of 0.1 second is S × 0.
1 × a πH ^2/4, since the projection light 5 is dust gas passage length L that has passed through dust amount Y of each sampling time generated from the dust generation source was determined by the following equation. Y = N × (0.5 / L ) × (S × 0.1 × πH 2/4)
In this example, since the laser irradiation direction is substantially perpendicular to the dust generation movement direction, H = L can be set, and the above equation is summarized as follows. Y = 13.5 × N × L × S FIG. 6 schematically shows the relationship between the elapsed time during which the lid of the melting furnace 40 is opened and closed and the amount of dust generated during the opening and closing as determined above. is there. Although the embodiment of measuring the amount of dust generated from the melting furnace of the foundry has been described above, it goes without saying that the amount of dust generated from other dust sources and the concentration of the dust can be measured in the same manner. No.

[0027]

The present invention described above has the following effects. 1) Since the light emitter and the light receiver are separated from each other, it is possible to cope with those having different dust generation ranges. 2) Since it is possible to perform measurement without causing the projector and the receiver to come into contact with dust gas, it is possible to prevent a decrease in accuracy due to dust gas adhering to an optical window or the like, and to use a high temperature or corrosive dust gas. Can be measured without damaging the equipment. 3) Since the absolute amount of dust can be measured, the magnitude of the degree of influence of the dust source on the environment and the effect after the countermeasures can be accurately grasped, which is effective for environmental improvement. 4) Since the dust concentration can also be measured, the quality of the dust atmosphere in the air at each location can be determined. 5) Since the slope of the linear regression equation for estimating the laser transmittance and the amount of dust is obtained by a calibration operation, it is possible to measure by performing the calibration operation even if the dust source and the dust properties are different. 6) Since the calibration operation can be performed in another place in advance, on-site measurement can be performed efficiently and in a short time. 7) If the signal processing of the laser intensity and the processing for calculating the amount of dust are manufactured by a hardware logic circuit, the control unit can be made compact and handling on site becomes easy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an entire configuration of a dust amount measuring device of the present invention.

FIG. 2 is a diagram for explaining a laser and control.

FIG. 3 is a diagram for explaining processing in a control unit for controlling laser projection light and incident light;

FIG. 4 is a diagram illustrating a second embodiment in which a control unit is simplified.

FIG. 5 is a diagram showing an example of obtaining a linear regression equation for two types of dust by a calibration operation.

FIG. 6 is a diagram showing a state of generation of dust amount due to opening and closing of a lid of a melting furnace.

FIG. 7 is a flowchart showing a procedure for measuring the amount of dust.

[Explanation of symbols]

1 ... laser projector, 2 ... light source, 5 ... projection light, 6 ...
Laser light receiver 9: optical axis opening window, 10: light receiving lens, 12: light receiving element, 13: incident light 14: calibrator, 17: signal processing unit, 18: optical window,
19: Aperture 20: Input / output unit, 22: Monitor, 26: Logarithmic operation unit, 27: Memory 28: Dust amount operation unit, 29: Output terminal, 30: Operation panel, 31: Display 33: Amplification rate adjusting means, 34: Offset value adjusting means 36: Dust gas measuring means 37: Video camera 38: Anemometer 39: Dust gas

Claims (5)

[Claims] A laser projector for projecting a laser beam;
A laser receiver for receiving the projection light separated from the laser projector, a logarithmic conversion value of the transmittance of the laser beam electrically connected to the laser projector and the laser receiver, and a set logarithmic conversion value and a set amount of dust. And a control unit for calculating the amount of dust based on the amount of dust gas generated, and a calibrator for obtaining a linear regression equation representing the relationship between the logarithmic conversion value and the amount of dust. Dust amount measurement device. 2. The calibrator is used at the time of a calibration operation for obtaining a constant indicating a slope of a linear regression equation specific to a measurement object prior to the measurement of the amount of dust, in which a medium is filled and dust is added and diffused. 2. The dust amount measuring device according to claim 1, wherein both end portions capable of being formed are light-transmitting cylinders, and the laser projection light can penetrate the cylinder along the axis. 3. The dust gas generation amount is obtained based on a dust gas generation width measuring unit and a dust gas moving speed measuring unit, and an absolute dust amount at predetermined time intervals is calculated as a dust amount. Item 3. The dust amount measuring device according to Item 1 or 2. 4. A logarithmic conversion value of transmittance is determined based on the intensity of light projected from a laser projector and the intensity of incident light from a laser receiver receiving the projected light. Calculate the dust amount of the calibration standard from the relational expression of the logarithmic conversion value and the amount of dust specific to the amount measurement object, measure the dust gas passage length of the laser projection light and the amount of dust gas generated, and correct the dust amount of the calibration standard. A method for measuring the amount of dust actually generated. 5. A calibrating operation is performed by projecting a laser beam from a laser projector from an axial direction every time a dust sample of a known weight is mixed with a calibrator of a predetermined length having a medium of a known capacity. 5. The method according to claim 4, wherein a logarithmic conversion value of the laser transmittance with respect to the amount of dust at this time is collected, a linear regression equation is determined from the logarithmic conversion equation, and a constant indicating the slope thereof is determined. Dust amount measurement method.