JP2009281930A - Particle concentration measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle concentration measuring apparatus adapted to the measurement of a concentration of particles for each component in the case that an object to be measured contains multi-component particles. <P>SOLUTION: The particle concentration measuring apparatus is constituted of a light source for irradiating measuring light having a wide range of an output wavelength to an object to be measured flowing through a transparent measuring cell, a light-receiving part comprising a plurality of optical sensors for measuring the intensity of transmitted light and scattered light generated by irradiation with the measuring light on different wavelengths, and an operation part for computing the concentration of particles in the object to be measured for each component on the basis of measurement results of each optical sensor of the light-receiving part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a particle concentration measuring apparatus, and more particularly, to a particle concentration measuring apparatus that can determine a multi-component particle concentration in a measurement object.

  In general, in water treatment processes such as purified water and wastewater, turbidity is measured in order to quantitatively grasp the turbid state of water as a specific numerical value and manage the water quality.

  FIG. 4 is a block diagram showing a schematic configuration example of a conventional transmission scattering turbidimeter used for such turbidity measurement. In FIG. 4, the output light of the light source 1 is converted into parallel light by a condenser lens 2 made of a collimator lens, and is irradiated to one end side of the measurement cell 3 as measurement light. As the light source 1, for example, a small tungsten lamp is used.

  The measurement cell 3 is a measurement flow path tube including parallel transparent glasses 31 and 32, and the liquid of the measurement sample S as a measurement target flows in the tube in a certain direction so as to be orthogonal to the axial direction of light. .

  The measurement light irradiated from the light source 1 to the transparent glass 31 that seals one end of the measurement cell 3 through the condenser lens 2 is scattered light F2 scattered by particles contained in the measurement sample S flowing inside the measurement cell 3. As the transmitted light F1 that passes without being scattered, it is emitted from the transparent glass 32 on the other end side.

  The transmitted light F1 emitted from the transparent glass 32 on the other end side is received by the transmitted light receiving part 4a formed in a disc shape and converted into an electric signal, and the scattered light F2 is concentric with the outer periphery of the transmitted light receiving part 4a. Are received by the ring-shaped scattered light receivers 4b arranged in the shape of the light and converted into electric signals.

  Output signals from the transmitted light receiving unit 4a and the scattered light receiving unit 4b are input to the arithmetic unit 5, where the scattering / transmission ratio is calculated and converted into a turbidity value. The turbidity value converted by the arithmetic device 5 is displayed on the display unit 6.

According to the configuration of FIG. 4, the turbidity value is obtained by dividing the scattered light signal by the transmitted light signal.
1) Not affected by the color of the object to be measured 2) Not affected by fluctuations in power supply and light quantity 3) Excellent effects such as being less susceptible to glass stains are obtained.

  Patent Document 1 below describes a turbidimeter configured using such a transmitted scattered light method.

JP 2006-329629 A

  By the way, in water quality management, measurement and management of particle concentrations of sand, soil, clay, iron powder and the like mixed in the measurement object are also important items. In addition, in the manufacturing processes of various manufacturing industries including the food industry, the concentration measurement of various particles contained in the measurement object is an important item from the viewpoint of process efficiency and quality control.

  However, the conventional transmission scattering turbidimeter can measure the total concentration of particles in the measurement liquid, but cannot measure the particle concentration of each component when the measurement liquid contains multi-component particles. In addition, since there is sensitivity in the visible light region, it is difficult to measure particles that are nearly transparent.

  Thus, for example, a laser scattered light type particle concentration measuring apparatus is used as necessary. However, since a laser is used, the sensitivity to specific particles is high, but the concentration of multicomponent particles cannot be measured simultaneously.

  There is an absorption (spectroscopic) photometric method as a method for measuring individual particle concentrations of multicomponents, but only the absorbance corresponding to the transmitted light is detected and the scattered light is not detected. Therefore, it is vulnerable to contamination of the measurement cell, and frequent maintenance is required when it is introduced to online measurement. In addition, the equipment becomes large and expensive.

  The present invention solves these problems, and its object is to provide a relatively small and simple system that can continuously measure the concentration of particles for each component when a multi-component particle is included in the measurement target. The object is to realize a particle concentration measuring apparatus having a structure.

In order to achieve the above object, the invention of claim 1
A light source for irradiating measurement light having a wide range of output wavelengths to a measurement object flowing in a transparent measurement cell;
A light receiving unit comprising a plurality of optical sensors for measuring the intensity of transmitted light and scattered light generated by irradiation of the measurement light for different wavelengths;
An arithmetic unit that calculates, for each component, the particle concentration in the measurement object based on the measurement results of the optical sensors of the light receiving unit,
The particle concentration measuring device is characterized by comprising:

The invention of claim 2 is the particle concentration measuring device according to claim 1,
The light receiving unit is
A transmitted light receiving unit disposed in the irradiation direction of the light source and receiving the transmitted light of the measurement object;
A scattered light receiving unit that is arranged at a predetermined angle from the irradiation direction of the light source and receives the scattered light of the measurement object;
A plurality of the optical sensors having sensitivity to different wavelengths are provided in each of the transmitted light receiving unit and the scattered light receiving unit.

The invention of claim 3 is the particle concentration measuring device according to claim 2,
The transmitted light receiving part is formed in a disc shape,
The scattered light receiving part is formed in a ring shape and is arranged concentrically on the outer periphery of the transmitted light receiving part.

The invention of claim 4 is the particle concentration measuring device according to any one of claims 1 to 3,
The measurement light irradiation surface of the measurement cell is formed in a planar shape, and the measurement light emission surface is formed in a convex curved surface,
The light receiving surface of the light receiving portion is formed in a concave curved surface so as to face the light emitting surface of the measurement light of the measurement cell.

The invention of claim 5 is the particle concentration measuring device according to any one of claims 1 to 4,
The calculation unit includes an analysis unit that determines which photosensor measurement result is to be selected when calculating the particle concentration,
This analysis part
Predetermined calculation is performed by arbitrarily combining the pre-measurement results of each optical sensor to be measured whose particle concentration of each component is known, and a set of optical sensors whose calculation result shows the highest correlation with the actual particle concentration It is determined for each.

The invention of claim 6 is the particle concentration measuring device according to any one of claims 1 to 5,
The arithmetic unit takes a ratio of the intensity of scattered light and the intensity of transmitted light.

The invention of claim 7 is the particle concentration measuring device according to any one of claims 1 to 6,
The plurality of photosensors having sensitivity to different wavelengths are an ultraviolet light sensor, a visible light sensor, and a near infrared light sensor.

  According to such an invention, when multi-component particles are included in the measurement target, the particle concentration for each component can be continuously measured, which is suitable for on-line measurement.

FIG. 1 is a configuration diagram of the first embodiment of the present invention, and FIG. 2 is a configuration diagram showing details of the light receiving unit 4 and the arithmetic unit 5 of FIG. 1, and the same reference numerals are given to portions common to FIG. .
The light source 1 emits light having a wide range of output wavelengths, such as a tungsten lamp, and the output light is converted into parallel light by the collimator lens 2 and irradiated to the measurement cell 3 as measurement light.

  The measurement cell 3 is a measurement flow path tube including parallel transparent glasses 31 and 32, and the liquid of the measurement sample S as a measurement target flows in the tube in a certain direction so as to be orthogonal to the axial direction of light. . These transparent glasses 31 and 32 are, for example, quartz glass and are installed so as to be perpendicular to the irradiation direction of the measurement light, and serve as windows for allowing the measurement light to pass through. In the measurement liquid S, it is assumed that particles of a plurality of components (component X, component Y, component Z) are dispersed.

  The measurement light applied to the measurement cell 3 passes through the transparent glass 31 and enters the measurement liquid S. The measurement light incident on the measurement liquid S is emitted from the transparent glass 32 as transmitted light F1, and a part of the measurement light is scattered by particles contained in the measurement liquid S to become scattered light F2 and F3, and is emitted from the transparent glass 32. Is done.

  The intensity of these scattered lights F2 and F3 varies depending on the concentration, size, shape, physical properties, and light wavelength of the particles. In addition, the scattering angle at which the intensity of the scattered light F2 and F3 is the highest also varies depending on the size, size, shape, physical properties, and light wavelength of the particles.

  The light receiving unit 4 is provided so as to face the transparent glass 32 of the measurement cell 3. The light receiving unit 4 includes a transmitted light receiving unit 40 that receives the transmitted light F1, and scattered light receiving units 41 and 42 that receive the scattered lights F2 and F3.

  The transmitted light receiving unit 40 is formed in a disc shape having a diameter substantially the same as the diameter of the measurement light beam that is paralleled by the collimator lens 2. The scattered light receiving portions 41 and 42 are arranged concentrically on the outer periphery of the transmitted light receiving portion 40 and are configured in a ring shape. The inner diameter of the scattered light receiving unit 41 is formed to match the outer diameter of the transmitted light receiving unit 40, and the inner diameter of the scattered light receiving unit 42 is formed to match the outer diameter of the scattered light receiving unit 41.

  The transmitted light receiving unit 40 is arranged at a distance d1 from the inner surface of the transparent glass 32 of the measurement cell 3 so that the center of the disk coincides with the light beam center of the measurement light. The scattered light receivers 41 and 42 are disposed concentrically with the transmitted light receiver 40 at a distance d2 (d2 <d1) from the inner surface of the transparent glass 32 of the measurement cell 3. The transmitted light receiving unit 40 and the scattered light receiving units 41 and 42 are arranged so as to be perpendicular to the irradiation direction of the measurement light. Note that the linearity of a calibration curve, which will be described later, can be adjusted by shifting the relative positions of the transmitted light receiving unit 40 and the scattered light receiving units 41 and 42.

  As shown in FIG. 2, the disc-shaped transmitted light receiving unit 40 is divided into three regions A <b> 1 to A <b> 3 at equal angular intervals (120 °) along the circumferential direction, and the ring-shaped scattered light receiving unit 41. Is divided into three regions A4 to A6 at equal angular intervals (120 °) along the circumferential direction, and the ring-shaped scattered light receiving part 42 is divided into regions at equal angular intervals (120 °) along the circumferential direction. It is divided into three parts A7 to A9.

The areas A1, A4 and A7 are provided with ultraviolet light sensor elements (D _uv ) to form ultraviolet light detection areas, respectively, and the areas A2, A5 and A8 are provided with visible light sensor elements (D _op ) and spread. Thus, visible light detection regions are formed, and near-infrared light sensor elements (D _ir ) are provided in the regions A3, A6, and A9 to form near-infrared light detection regions, respectively.

The measurement light irradiated to the measurement cell 3 and passed through the measurement liquid S becomes transmitted light F1 and scattered light F2 and F3, and the three types of optical sensor elements D _uv , whose light intensities are sensitive to different wavelengths in the respective detection regions. It is measured by D _op and _Dir . Outputs of the respective optical sensor elements D _uv , D _op and D _ir are digitized by an A / D converter (not shown) and then stored in the memory 51 of the arithmetic unit 5.

The particle concentration calculation unit 52 reads the output of each photosensor element D _uv , D _op , D _ir from the memory 51, and outputs the output of the photosensor element included in each detection region A 1 to A 9 of the light receiving unit 4. The average value is calculated. Thereby, the intensity | strength of the light in an ultraviolet light area | region, a visible light area | region, and a near-infrared light area | region is obtained about the transmitted light F1 and scattered light F2, F3. The following values are obtained as a result of the calculation.
Transmitted light F1: detection area (A1, A2, A3) = (ultraviolet, visible, near infrared)
= Intensity (I ₁₁ , I ₁₂ , I ₁₃ )
Scattered light F2: detection region (A4, A5, A6) = (ultraviolet, visible, near infrared)
= Intensity (I ₂₁ , I ₂₂ , I ₂₃ )
Scattered light F3: detection region (A7, A8, A9) = (ultraviolet, visible, near infrared)
= Intensity (I ₃₁ , I ₃₂ , I ₃₃ )

  The analysis unit 53 is used at the time of initial setting or maintenance of the particle concentration measuring device and at the time of creating a calibration curve, and is not used at the time of actual measurement of the particle concentration measuring device. The calibration curve refers to a relationship line between a particle concentration and a measured value of various physical quantities such as absorbance, current, voltage, resistance, and the like related to the particle concentration obtained using a measuring solution having a known particle concentration.

  Prior to the actual measurement by the particle concentration measuring apparatus, the measurement solution S ′ for calibration with a known particle concentration of the component X is measured. The detection signal intensities of the transmitted light F <b> 1 ′ and scattered light F <b> 2 ′ and F <b> 3 ′ obtained by this measurement are input to the analysis unit 53.

  The analysis unit 53 selects all the detection regions from the detection regions A1 to A3 of the transmitted light receiving unit 40 and the detection regions A4 to A9 of the scattered light receiving units 41 and 42, respectively. The ratio of the detected signal intensity is obtained for. The calculated detection signal intensity ratio value is introduced into a predetermined calculation formula for converting the particle concentration of the component X into the particle concentration of the component X, and the particle concentration of the component X is calculated.

  The calculation of the particle concentration of the component X is performed by changing the particle concentration of the component X in the calibration measuring solution S ′ from a low concentration to a high concentration. Then, for each combination of the areas where the ratio of the detection signal intensity is calculated, a correlation coefficient with the result of the manual analysis of the calibration measuring solution S ′ from a low concentration to a high concentration is calculated. A method such as neural network or multivariate analysis is used to calculate the correlation coefficient. As a result of the calculation, a combination of detection areas showing the highest correlation coefficient is determined as a combination of detection areas for component X measurement. The combination of detection areas means a combination of optical sensor elements in the detection areas. Then, a calibration curve of the component X is created using the detection signal intensity ratio and particle concentration calculation result calculated for this combination of detection regions.

The analysis unit 53 performs the above-described processing for the component Y and the component Z, respectively, determines the combination of detection regions showing the highest correlation coefficient with the result of manual analysis and creates a calibration curve.
As a result of the analysis by the analysis unit 53, the combination of detection areas for component X, Y, Z measurement is
Component X: detection area A4 / detection area A1
Component Y: Detection area A8 / Detection area A3
Component Z: detection area A9 / detection area A2
Shall be determined.
The determined combination of detection areas and the calibration curve are output from the analysis unit 53 to the particle concentration calculation unit 52 and stored in the particle concentration calculation unit 52.

For each component, the particle concentration calculation unit 52 selects the detection signal intensity of the combination detection region determined by the analysis unit 53 and calculates the ratio of the detection signal intensity.
Component X: detection area A4 / detection area A1 = I ₂₁ / I ₁₁
Component Y: detection area A8 / detection area A3 = I ₃₂ / I ₁₃
Component Z: detection area A9 / detection area A2 = I ₃₃ / I ₁₂

  The particle concentration calculation unit 52 compares the detection signal intensity ratio value calculated for each component with a calibration curve to calculate the particle concentration. The obtained particle concentration is displayed on the display unit 6. Although the arithmetic unit 5 is shown as a functional block, it is actually performed by a computer in which a program for performing each arithmetic operation is installed.

  The present embodiment is configured as described above, and the light receiving unit 4 includes a plurality of photosensors having sensitivity to different wavelengths, and by selectively using the measurement results of these photosensors, each component of the measurement liquid S is provided. Particle concentration can be measured.

  Note that the particle concentration measuring apparatus described in the present embodiment can also be used as a turbidimeter that calculates the turbidity of the measurement liquid S based on the particle concentration.

  In addition, since optical sensors having sensitivity to different wavelengths are provided in the transmitted light receiving unit 40 and the scattered light receiving units 41 and 42, detection signals with different wavelengths for the transmitted light F1 and the scattered light F2 and F3, respectively. The intensity can be measured.

  In addition, the transmitted light receiving unit 40 has a disk shape, the scattered light receiving units 41 and 42 have a ring shape concentrically arranged with the transmitted light receiving unit 40, and the outer diameter and inner diameter of each light receiving unit are made continuous. The intensity of the scattered light F2 and F3 can be measured for each of a plurality of spatially continuous small angles. As a result, most of the scattered light can be measured, and the particle concentration can be measured with high accuracy. In addition, since the scattered light receiving portions 41 and 42 are double, scattered light having different scattering angles can be measured.

  In addition, in the calculation of the particle concentration, an analysis unit 53 that determines which detection region of the light detection signal intensity measured in which detection region is used, that is, which optical sensor measurement result is selected, is provided. A result close to that which would be obtained if S was manually analyzed is obtained.

  In continuous measurement, it is very important to limit the measurement error to an allowable range and lengthen the maintenance cycle of the apparatus. However, the particle concentration calculation unit 52 calculates the scattered light F2 and F3 when calculating the particle concentration. Since the ratio of the detection signal intensity and the detection signal intensity of the transmitted light F1 is obtained, it is not easily affected by fluctuations in the power supply of the apparatus, the light quantity of the light source, and the measurement cell window stains caused by the measurement target. It is possible to measure the particle concentration continuously online without applying any.

Moreover, since the ultraviolet light sensor element D _uv , the visible light sensor element D _op , and the near infrared light sensor element D _ir are used as a plurality of light sensor elements having sensitivity to different wavelengths, the transmitted light can be transmitted in a wide wavelength region Scattered light can be measured.

  In this embodiment, the scattered light is detected only by the scattered light receiving parts 41 and 42. However, by adding a ring-shaped detection part to the outer periphery of the scattered light receiving part 42, the scattered light is scattered at a larger angle. Scattered light can also be measured.

In this embodiment, three types of optical sensor elements are used as optical sensors having sensitivity to different wavelengths, but the number of sensor elements is not limited to three. The greater the number and type of photosensor elements, the more accurately the particle concentration can be measured. Furthermore, although the ultraviolet light sensor element D _uv , the visible light sensor element D _op , and the near infrared light sensor element D _ir are used in the present embodiment, the type of the light sensor element is not limited to this. However, it is desirable to use a wavelength in which the wavelengths having sensitivity do not overlap each other.

  Note that the measurement liquid S corresponds to a measurement object in claims, and the particle concentration calculation unit 52 corresponds to a calculation unit in claims. Further, the present invention can be used not only for measuring the concentration of particles in a liquid but also for measuring the concentration of particles in a gas.

  In the first embodiment, the light receiving portion 4 is formed in a planar shape. However, the light receiving portion 4 may be formed in a curved shape. FIG. 3 shows an example in which the light receiving part has a concave curved surface as the second embodiment. 3A is a perspective view of the light receiving portion 4 ′, FIG. 3B is a top view of the light receiving portion 4 ′, and FIG. 3C is a development view of the light receiving portion 4 ′.

  The entire measurement cell 3 ′ is made of, for example, quartz glass, and the measurement liquid S flows inside. The incident side of the measurement light is formed in a plane, the emission side of the measurement light is formed in a convex curved surface, and the incident side plane is installed so as to be perpendicular to the irradiation direction of the measurement light.

  The light receiving portion 4 ′ is formed in a concave curved surface so as to face the emission surface of the measurement cell 3 ′. The vertical edge of the light receiving portion 4 ′ is located on the same plane as the incident side wall of the measurement cell 3 ′.

  The light receiving unit 4 ′ is provided with a transmitted light receiving unit 40 ′ that receives transmitted light and scattered light receiving units 41 ′ to 45 ′ that receive scattered light. The scattered light receiving parts 41 ′ to 45 ′ are arranged concentrically with the transmitted light receiving part 40 ′, and the outer diameter of the scattered light receiving part 43 ′ is the horizontal length (when unfolded) of the light receiving part 4 ′. Match.

  Each of the transmitted light receiving unit 40 ′ and the scattered light receiving units 41 ′ to 45 ′ is divided into three regions, and an ultraviolet light sensor element, a visible light sensor element, and a near infrared light sensor element are provided for each divided region. It is laid down. Other configurations are the same as those of the first embodiment.

  Since the present embodiment is configured as described above, it has the same effect as the first embodiment, and further, the exit side of the measurement cell 3 ′ is formed as a convex curved surface, and the surface of the light receiving portion 4 ′ facing the measurement cell 3 ′. By using a concave curved surface, it is possible to receive scattered light having a larger scattering angle than when the light receiving portion is planar. For example, the scattered light F4 scattered at 90 degrees in the horizontal direction from the measurement light irradiation direction can also be detected.

  As described above, according to the present invention, when multi-component particles are included in the measurement target, the particle concentration measuring device having a relatively small and simple structure capable of continuously measuring the particle concentration for each component. It can be realized and is suitable for measuring and managing the concentration of particles in a fluid in a manufacturing process of various manufacturing industries such as a water treatment process and the food industry.

It is a figure which shows the structure of Example 1 of this invention. It is a figure which shows the light-receiving part and arithmetic unit of FIG. It is a figure which shows the structure of Example 2 of this invention. It is a block diagram which shows the schematic structural example of the conventional transmission scattering type turbidimeter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Collimator lens 3 Measurement cell 31, 32 Transparent glass 4 Light-receiving part 40 Transmitted light light-receiving part 41, 42 Scattered light light-receiving part 5 Arithmetic device 51 Memory 52 Particle concentration calculation part 53 Analysis part 6 Display part S Measurement liquid

Claims (7)

A light source for irradiating measurement light having a wide range of output wavelengths to a measurement object flowing in a transparent measurement cell;
A light receiving unit comprising a plurality of optical sensors for measuring the intensity of transmitted light and scattered light generated by irradiation of the measurement light for different wavelengths;
An arithmetic unit that calculates, for each component, the particle concentration in the measurement object based on the measurement results of the optical sensors of the light receiving unit,
A particle concentration measuring apparatus comprising: The light receiving unit is
A transmitted light receiving unit disposed in the irradiation direction of the light source and receiving the transmitted light of the measurement object;
A scattered light receiving unit that is arranged at a predetermined angle from the irradiation direction of the light source and receives the scattered light of the measurement object;
The particle concentration measuring device according to claim 1, wherein the plurality of optical sensors having sensitivity to different wavelengths are provided in each of the transmitted light receiving unit and the scattered light receiving unit. The transmitted light receiving part is formed in a disc shape,
3. The particle concentration measuring apparatus according to claim 2, wherein the scattered light receiving unit is formed in a ring shape and arranged concentrically on the outer periphery of the transmitted light receiving unit. The measurement light irradiation surface of the measurement cell is formed in a planar shape, and the measurement light emission surface is formed in a convex curved surface,
The particle concentration measuring apparatus according to claim 1, wherein the light receiving surface of the light receiving unit is formed in a concave curved surface so as to face a measurement light emitting surface of the measurement cell. The calculation unit includes an analysis unit that determines which photosensor measurement result is to be selected when calculating the particle concentration,
This analysis part
Predetermined calculation is performed by arbitrarily combining the pre-measurement results of each optical sensor to be measured whose particle concentration of each component is known, and a set of optical sensors whose calculation result shows the highest correlation with the actual particle concentration The particle concentration measuring device according to claim 1, wherein the particle concentration measuring device is determined every time.   The particle concentration measuring apparatus according to claim 1, wherein the calculation unit takes a ratio between the intensity of scattered light and the intensity of transmitted light.   The particle concentration measurement apparatus according to claim 1, wherein the plurality of optical sensors having sensitivity to different wavelengths are an ultraviolet light sensor, a visible light sensor, and a near infrared light sensor.

Images