JPH03220444A - Measuring method of absorbing state and measuring apparatus of absorption - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention makes measurement light enter a fluid to be measured from an irradiation window, and uses the measurement light that is received by a light receiving window after passing through the fluid to be measured. A light absorption state measuring method for measuring the light absorption state of the fluid to be measured, an irradiation window for allowing measurement light from a light source to enter the fluid to be measured, and a light emitted from the irradiation window and transmitted through the fluid to be measured. The present invention relates to an absorption measuring device in which a light receiving window for receiving measurement light and allowing a light receiving means for measuring the state of light absorption to receive the light is provided at a distance.

[Conventional technology]

The above-mentioned measurement of the light absorption state of a fluid can be carried out, for example, by determining the concentration of the fluid to be measured that is proportional to the absorption coefficient obtained, or by analyzing the spectrum of the measurement light received by the light receiving window to identify the components of the fluid to be measured. It is for doing things. However, in this measurement, the measurement light enters the fluid to be measured through the irradiation window, and then the measurement light that has passed through the fluid to be measured is extracted from the light reception window. Since it is in contact with the fluid to be measured, if measurements are continued for a long period of time,
Due to dirt or scratches on the irradiation window and the light receiving window, the absorption of light at the irradiation window and the light receiving window changes. However, the intensity of the measurement light obtained will be different from the point at which there is no dirt or flaw. Therefore, conventionally, maintenance work has been carried out such as cleaning the irradiation window and light receiving window on a regular basis, and replacing the irradiating window and light receiving window with new ones when they become dirty, or the effects of such changes over time. In order to eliminate this, the measuring system must be calibrated before starting the measurement, for example on the basis of the intensity of the measuring light obtained at a time when there are no stains or scratches - as is done when fishing on a boat. There is.

[Problem to be solved by the invention]

However, in the conventional measurement described above, that is, in the measurement using the conventional light absorption state measurement method or in the measurement of the light absorption state using a conventional light absorption measuring device, when performing maintenance work for the former, it is difficult to perform the maintenance work. This requires a great deal of labor and requires interruption of the fluid flow, which lowers the operating rate.Especially when the fluid being handled is sludge or something with high turbidity, it tends to get dirty and maintenance is difficult. It is not efficient as it requires frequent calibration work, and when performing the latter calibration work, the calibration work that is required prior to each measurement is troublesome, and the calibration work is troublesome. Therefore, it is necessary to obtain the reference intensity of the measurement light using a fluid whose absorption coefficient is known, which poses a problem in that the work is time-consuming.

In view of the above-mentioned circumstances, the purpose of the present invention is to provide a system that is not affected by dirt, scratches, etc. even when measurements are carried out over a long period of time.
Another object of the present invention is to provide a light absorption state measuring method and a light absorption measuring device that allow continuous measurement without interrupting the flow of the fluid to be measured.

[Means to solve the problem]

The light absorption state measuring method according to the present invention, which is the first means taken to achieve the above object, is characterized by an irradiation window for allowing measurement light from a light source to enter the fluid to be measured, and a light emitted from the irradiation window. and a light-receiving window for receiving the measurement light transmitted through the fluid to be measured and having it received by the light-receiving means for measuring the light absorption state, in a first measurement state in which the light-receiving window is positioned at a set distance. The intensity of the first measurement light and the second measurement light received by the light reception window in a second measurement state in which the irradiation window and the light reception window are positioned apart from each other by a set distance different from the first measurement state. Using the intensity of the measurement light, k
-(1/ΔL)l! oga Iout/I'out) where, k: Absorption coefficient ΔL in the fluid to be measured: Difference in the separation distance between the irradiation window and the light receiving window between the two measurement states Iout: Intensity of the first measurement light I'out: The purpose is to obtain the absorption coefficient of the fluid (S) to be measured using the second measurement light intensity equation.

Further, the characteristic configuration of the absorption measuring device according to the present invention, which is the second means taken to achieve the above object, is that the irradiation window and the light receiving window are provided so as to be relatively movable along the transmission direction of the measurement light. measurement distance changing means for changing the separation distance by relatively moving the irradiation window and the light receiving window; and the intensity of the second measurement light, k= (1/ΔL)・fogs Iout/I'out
) where k: absorption coefficient of the fluid to be measured ΔL = difference in separation distance between the irradiation window and the light receiving window between the two measurement states Iout: intensity of the first measurement light I'out: intensity of the second measurement light The present invention further includes a calculation means for determining the absorption coefficient of the fluid to be measured using an intensity formula.

[For production]

In other words, in measuring this type of light absorption state, the measurement is complicated and the sensitivity of the measurement system is affected, so instead of measuring the absolute value of the intensity of the measurement light, it is generally The ratio of the intensity of the measurement light incident on the fluid (hereinafter referred to as incident light) to the intensity of the measurement light received after passing through the fluid to be measured (hereinafter referred to as output light) is determined. It is known that the following relationship exists between the above-mentioned ratio and the absorption coefficient of the fluid to be measured, according to the Langhardt-Helle law. That is, Iout/1. ,=e−”L ■However, I
out: intensity of emitted light 11) 1: intensity of incident light: absorption coefficient of the fluid to be measured L: separation distance between the irradiation window and the light receiving window. Generally, the absorption coefficient is determined using this equation.

Here, if absorption by the irradiation window and the light receiving window is introduced into the above equation 0, then Iout/IB=e-"°1゛1' ■However, a: Absorption by the irradiating window and the light receiving window, etc. If the irradiation window and the light receiving window become dirty or scratched, the value of [a] in the above equation 0 will change, making it impossible to accurately determine the absorption coefficient.

However, although this absorption changes over a long period of use, it does not change even if the positional relationship between the irradiation window and the light receiving window changes at approximately the same time.

Therefore, the second
When measurement is carried out under the measurement conditions, the relationship between the intensity of the emitted light obtained in this case and the absorption coefficient of the fluid to be measured is I'out/I,, -e-(k''''''
(2) However, I'out: Intensity of emitted light in the second measurement state L': Separation distance between the irradiation window and the light receiving window in the second measurement state (=L+ΔL).

Therefore, when equations 0 and 0 are combined and solved for [k], (Iout/ I I N) I'out/ItN)
= e(”°l-+all /(e-1°L'
on+) ■out/f'. ut=e(-ni-L-a〉-(-ni'
L'-a)=ek-(1-1'), taking the logarithm of both sides, log, Iout/I'out)=, (L'-L)=
Since k・ΔL, in the end, k=(1/ΔL)・l Ig, (Iout/I′out
)■ The absorption coefficient of the fluid to be measured can be determined. As is clear from this equation, when calculating the absorption coefficient, the elements of absorption by the irradiation window and the light reception window are removed, and the separation distance between the irradiation window and the light reception window is not necessary, and the two measurement conditions are It is only necessary to know the difference in their separation distances, and the intensity of the measurement light incident on the fluid to be measured does not need to be known. Calculation based on the formula 0 above using the intensities of the two measurement lights allows accurate measurement at all times, regardless of age-related changes in the measurement system, without being affected by dirt or scratches on the irradiation light or the light receiving window. This allows the absorption coefficient of the target fluid to be determined.

Further, as claimed in claim 2, in an absorption measuring device equipped with a measuring means incorporating an algorithm for determining an absorption coefficient as described above, a measuring distance changing means for varying the distance M between the irradiation window and the light receiving window is provided. Coupled with the switching between the two measurement states, the calculation means automatically calculates the absorption coefficient of the fluid to be measured, making it possible to perform measurements extremely simply and quickly.

[Effects of the Invention] As a result, according to the light absorption state measuring method of the present invention, the measurement target can be accurately measured at all times without being affected by absorption by the irradiation window, the light receiving window, etc., regardless of the aging of the measurement system. Since the absorption coefficient of the fluid can be determined, there is no need to perform troublesome maintenance work that requires a lot of effort and may reduce the operating rate, or it is no longer necessary to perform troublesome and time-consuming calibration work every time a measurement is made. Since the measurement can be carried out over a long period of time, and the flow of the fluid to be measured is not interrupted during the measurement, the light absorption state of the fluid can be measured easily as a whole.

Furthermore, the separation distance between the irradiation window and the light receiving window is not necessary, and the difference between the two measurement states only needs to be η.
For example, when the irradiation window and the light reception window are divided and they are used to connect a flow path with an unknown flow path diameter, it is only necessary to accurately know the position of one window, and the flow path of the measurement system It also has the advantage of being easy to install. In addition, since the intensity of the light incident on the fluid to be measured is not required, a configuration for measuring the intensity of the measurement light only needs to be provided on the light receiving side, which has the advantage of simplifying the measurement system. .

In addition, the absorbance measuring device of the present invention is an example of implementing the absorbance state measuring method of the present invention, and in addition to the above-mentioned effects, it further simplifies the measurement work by automating the measurement procedure. In addition, it is possible to speed up the process.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings. In addition,
Since an example of the method for measuring the light absorption state of the present invention is realized by the light absorption measuring device of the present invention, the detailed description of the present invention will include a description of the light absorption measuring device, and will also serve as a description of both inventions. conduct.

As shown in Figures 1 and 2, the fluid to be measured (S)
At mutually opposing locations on the pipe wall of the transport pipe (p) through which
An irradiation window (3) through which the measurement light emitted from the light source (1) and shaped into a parallel beam by the collimator lens (2) enters the fluid to be measured (S); A light-receiving window (6) receives the measurement light transmitted through the fluid to be measured (S), condenses it with a condenser lens (4), and then causes the light-receiving element (S), which is a light-receiving means for measuring the light absorption state, to receive the light. ) are distributed and arranged, and the light receiving element (5
) for measuring the light absorption state of the measurement target fluid (S) using the photocurrent received and photoelectrically converted by
7) to constitute an absorption measuring device.

An auxiliary chamber (8) having a shape that bulges out laterally is formed in the part of the flow path where the light receiving window (6) is provided, and the light receiving window (6) is provided in the auxiliary chamber (8). - A light receiving unit (R) consisting of a condensing lens (4) and a light receiving element (5) is housed in a state supported by the tube wall via a diaphragm (9), and the light receiving unit (R) is A pair of flips (lO) are provided for expanding and contracting the diaphragm (9) so as to change its position along the radial direction of the transport pipe ([]).

This pair of flips (10) is configured to be driven to expand and contract by control signals from a control device (C) including the calculation means (7). and the calculation means (7)
is the above-mentioned flip (10) which is the measurement distance changing means.
The light receiving unit 7 (
The light receiving element (5) was measured in two measurement states in which the separation distance between the irradiation window (3) and the light receiving window (6) was changed by moving the light receiving element (5).
) is configured to determine the absorption coefficient of the fluid to be measured (S) using the following equation using the intensities of the first and second measurement lights received separately. That is, k-(1/ΔL)l! og* Iout/I'out)
where, k: Absorption coefficient of the fluid to be measured ΔL: Difference in separation distance between the irradiation window and the light receiving window between the two measurement states rout: Intensity of the first measurement light I'out: Intensity of the second measurement light In other words, from Langheld-Herr's law related to the light absorption state of the fluid, the intensity CIIN of the incident light on the fluid to be measured (S)
] and the intensity [Iout] of the emitted light after passing through the fluid to be measured (S) is the absorption coefficient [Iout] of the fluid to be measured (S).
k] and the separation distance [L] between the irradiation window (3) and the light receiving window (6), and the relational expression can be expressed as Iout/I+s=e −”'. Considering absorption [a] by the irradiation window (3) and the light receiving window (6) other than absorption by (S), the above equation can be expressed as Iout/11H=e −”°1゛1, so the irradiation The intensity of the two emitted lights [Iou
t, I'out], Iout/I+
N=e-""a) I'out/I+N=e-"°1"+ straight, L'=
By obtaining the relational expression L + ΔL, combining them and solving for the absorption coefficient [k], we can remove the influence of the absorption fa due to the irradiation window (3) and the light reception window (6), etc., which change over time. This makes it possible to easily and quickly measure the state of light absorption continuously over a long period of time. That is, k-(1/ΔL)l! og, Iout/I'out)
Therefore, the absorption coefficient Fk] is determined.

[Another example]

Next, another example of the present invention will be listed.

In the absorption state measuring method, after measuring the intensity of the first measurement light and the intensity of the second measurement light, the absorption coefficient [
k] may also be obtained.

<2> In the absorption measurement device, the irradiation window (3) and the light reception window (
6) is installed on the pipe wall of the transport pipe (P), and in addition to the irradiation window (3) and the light receiving window (6), the light source (1), the light receiving element (5), the measuring means (7), etc. It has an integrated and portable configuration, and when measuring, the irradiation core (3) and light receiving window (6)
) may be immersed in the fluid to be measured (S) to perform the measurement.

3) In the absorption measuring device, the irradiation window (3) may be moved instead of moving the light receiving window (6). In short, the irradiating window (3) and the light receiving window (6) are The specific configuration of the measurement distance changing means can be changed as appropriate as long as it moves along the transmission direction of Any configuration may be used as long as the difference in separation distance from the light receiving window (6) can be detected by the measuring means.

(4) The type of light source (1), the type of light receiving means (5), etc. are arbitrary. Further, the type of fluid to be measured (S) is not particularly limited.

<5> Measurements according to the present invention are not limited to simply measuring absorption coefficients over all wavelengths, but also include performing spectral analysis from measurement results obtained at different wavelengths using various monochromatic lights. good.

4. Reference numerals are written in the claims section for convenience of comparison with the drawings, but the present invention is not limited to the structure shown in the accompanying drawings by these markings.

[Brief explanation of drawings]

The drawings show embodiments of the light absorption state measuring method and the light absorption measuring device according to the present invention, and FIGS. 1 and 2 are schematic configuration diagrams of the light absorption measuring device in different measurement states. (1)...Light source, (3)...Irradiation window,
(5)... Light receiving means, (6)... Light receiving window, (7)... Calculating means, (lO)...
・Measurement distance changing means, (S)...Fluid to be measured.

Claims (1)

[Claims] 1. The measurement light is made to enter the fluid to be measured (S) through the irradiation window (3), and after passing through the fluid to be measured (S), the measurement light is received by the light receiving window (6). A first measurement state in which the irradiation window (3) and the light reception window (6) are located apart from each other by a set distance. the intensity of the first measurement light received by the light receiving window (6), and positioning the irradiation window (3) and the light receiving window (6) at a set distance different from this first measurement state. In the second measurement state, the light receiving window (6
) and the intensity of the second measurement light received in k=(1/ΔL)・log_eIout/I′out)
where, k: Absorption coefficient of the fluid to be measured ΔL: Difference in separation distance between the irradiation window and the light receiving window between the two measurement states Iout: Intensity of the first measurement light I'out: Intensity of the second measurement light A light absorption state measuring method for determining the absorption coefficient of the fluid to be measured (S) using the following equation. 2. An irradiation window (3) for allowing the measurement light from the light source (1) to enter the fluid to be measured (S), and the light emitted from the irradiation window (3) and transmitted through the fluid to be measured (S). In an absorption measuring device, a light receiving window (6) for receiving measurement light and allowing the light receiving means (5) for measuring the light absorption state to receive the light is provided separately from the light receiving window (6). )
and a measurement distance changing means (10) which is provided so as to be relatively movable along the transmission direction of the measurement light, and which changes the separation distance by relatively moving the irradiation window (3) and the light reception window (6); Using the intensities of the first and second measurement lights separately received by the light receiving means (5) in two measurement states with different distances from each other by the distance changing means (10), k=(1/ΔL )・log_eIout/I'out)
where, k: Absorption coefficient of the fluid to be measured ΔL: Difference in separation distance between the irradiation window and the light receiving window between the two measurement states Iout: Intensity of the first measurement light I'out: Intensity of the second measurement light An absorption measuring device comprising: calculation means (7) for determining the absorption coefficient of the fluid to be measured (S) according to the equation.