JPS6148735A - Measuring device for concentration and partial pressure of gas - Google Patents

Abstract

PURPOSE:To remove a back light noise and to take accurate measurement by providing rotary sectors which rotate synchronously with each other on the optical axis of laser light emitted toward gas to be measured and a reflecting mirror between both sectors, and further providing a parabolic mirror for convergence and a spectroscope on the optical axis of reflected light. CONSTITUTION:The rotary sectors 4A and 4B which rotate in synchronization with each other are provided on the optical axis of light emitted by a light source 1 through an elliptic mirror 2 and a parabolic mirror 3; a transmission hole 14 and a total absorbing surface 15 are arranged on the sector 4A at the light source side and a total reflecting surface 16, a total absorbing surface 16, and a transmission hole 4 are arranged on the sector 4B at the side of the gas to be measured. A half-mirror 6 is arranged between the sectors 4A and 4B and a reflecting surface 7 is provided behind the gas 9 to be measured. Reflected light from the mirror 6 is incident on a spectroscope 10 through an off-axis parabolic mirror 8 and a photodetector 11 detects light emitted by the spectroscope 10. Measurement light and reference light pass through a window 13 provided to a main body 12. Thus, the concn. and partial pressure of many kinds of gas are measured simultaneously and accurately while a back light noise is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is applicable to various heat treatment furnaces used in the steel industry, and other processes that are used in various industries to determine the concentration and partial pressure of atmospheric gases. The present invention relates to a measuring device for measuring i.

(Conventional technology) Gas component concentrations and partial pressures, including heating furnaces and annealing furnaces used in the steel industry! There are many processes that take place in controlled atmospheres, in which it is essential to measure the concentration and partial pressure of gases. Therefore, currently there are two methods: one is to directly insert a measurement probe into the atmosphere to be measured, and the other is to aspirate the scum to be measured using an appropriate device and determine it outside the process. It is being done.

(Problem to be solved by the invention) However, these methods cannot be used under harsh conditions, such as when the process atmosphere is at high temperature and pressure, or when the atmosphere is composed of highly corrosive gaseous components. !
111 There is a limit to the heat resistance, pressure resistance, and 1lliJ corrosion performance of the foot probe, and there is a limit to the gas resistance! There have been occasional problems such as the loss of waste components due to the removal of the waste, and there have been cases in which accurate full determination has not been possible.

The unreleased 11 solves the STj point as shown in 1; and uses the absorption intensity of the light to directly pass the light of 1111I Sadakawa through the control atmosphere during the process, thereby eliminating the background noise. It is an object of the present invention to provide an apparatus that accurately determines the concentration and partial pressure of the waste components while constantly removing the influence of As mentioned above, the concentration and zero partial pressure of a gas are measured using the absorption intensity of light. Two rotating sectors are provided, and a half mirror is provided between the rotating sectors to reflect the light reflected by the reflecting surface provided at the rear of the constant gas to be 4111, and further 6 nuclear reflected light) 11
1 + J2 condensing paraboloid, spectrometer and light detection 2:
(6) and a total absorption surface and a transmission hole are provided in the rotation sector on the light source side of the rotation upper rotation sector described in +iii, and a total absorption surface and a transmission hole are provided in the other rotation sector. 11.

First, the measurement principle of the device of the present invention will be explained.

As shown in Table 1, gas molecules correspond to 41
It strongly absorbs light of a certain wavelength. Therefore, the method of determining the absorption intensity of the gas using light with this specific absorption wavelength and measuring the concentration of the target scum from this is 1, for example, as disclosed in Publication No. 01351-20904. It's already been done.

Table 1 In addition to the light having the absorption wavelength of the above-mentioned special W (hereinafter referred to as measurement light), the device of the present invention also uses light with a wavelength close to the absorption wavelength or not subject to optical absorption (hereinafter referred to as reference light 9). In addition, the measurement light and the reference light are made to pass through the same optical path, and the measurement light and the reference light are set to the light intensity of the light source (hereinafter referred to as initial intensity) and to pass through a constant gas and undergo light absorption by the gas. The light intensity (hereinafter referred to as the final intensity) is 4 (
11, and the average value of the scum concentration is measured from these values.

In general, light absorption follows the Lambert-Beer law: I(L) =IOexp(-ct*n
It is expressed as L). Here, I(0) is the initial intensity, n is the volume molar 0 degrees of the target j[]1 constant gas, L is the optical path length, α is the absorption coefficient, and I (L) is the final intensity. The absorption coefficient α is a physical constant determined by −4 (−4) depending on the wavelength used in a constant gas.

Therefore, in the present invention, the measurement light, the reference light, and the backlight g
4111, the rotating sector on the light source side (hereinafter No.
, is called l sector. ) is provided with a transmission hole and a total absorption surface, and the other (measured gas side) rotating sector (hereinafter referred to as N002 sector) is provided with a total reflection surface, a total absorption surface, and a transmission hole, as shown in Table 2. 4+11 combinations are formed, and for combination (2), the initial intensity is measured; for odor, the dark noise of detection Z: ; is measured; for (c), the final intensity is measured; and for (2), the emitted light as blue light noise is measured.

In Table 2, the light arches 11 to 14 formed by A8) are like L-missing by the combination of rotating sectors.

In the case of one combination ■ I 1= IAI (o) + I
I r = IA2 (0) + I // I suggest // I2 = engineering z //
・3 no tt I 3 =
K IU (o)exp(-cc A1
@ n L) + I8 + IZ I 3 = K I A2 (o) exp (-
αA2 ψ n・L)+I≦+11 // (a3 // I4 =IB +
IzIa=To+T- A4. ．． j L, entering, is a festival! +, wavelength of light, input 2 is a
ll+constant light) UD length αA1 is 1. The absorption coefficient for Chairman's entry 1, αA2 is the absorption coefficient for Kichoiri 2, engineering λ1
(0) is the initial intensity of the reference light, Iλ2(0) is the expected intensity of A111, n is the volume molar concentration of the electric substance to be covered, L is the optical path length, Iz is the background noise of the detector, and 1B is the backlight. The intensity of the component of iJU Nagairi 1 behind the emitted light as noise, 9 is the intensity of the component of j Skin Nagairi 2 of the emitted light, K
is a coefficient representing optical loss other than optical absorption by the gas to be measured. (Note that this coefficient is calculated by the l of the window crow existing in the optical path
It represents the loss due to F'J deviation and the loss due to part of the measurement light missing in the optical path. ). In the above equations, those without Gunshu represent the light intensity with respect to the reference light, and those with Tanyu represent the light intensity with respect to the measurement light.

As a result, the transmission of the reference light and Jl'l constant likelihood; t R, , R2 further becomes the transmittance ratio R, and it is possible to eliminate the unknown coefficient K that changes over time. Also, since the reference target is not absorbed by the gas to be measured, αA2〉〉αA1 can be set, and therefore the transmittance ratio R is R-exp(αg I n SL )
−・−(2) Yell. Furthermore, by taking the logarithm of both sides of this equation (2), we can organize the volume molar concentration n of the gas to be measured. Therefore, this volume molar concentration n and the gas state equation % formula % (4) (where P is the partial pressure of the gas to be measured, T is the temperature of the gas to be measured,
By combining R with gas constant 8, the partial pressure of the target 4111 constant gas can be determined as 1llll+.

The device of the present invention is a device for measuring the concentration and partial pressure of a constant Al11 gas based on such a theory.The present invention will be explained below with reference to the drawings. In the figure, 1 is a light 17, 2 is an ellipsoidal mirror for condensing the emitted light from light source 1, 3 is a parabolic mirror for creating a parallel beam, and 4A and 4B are mirrors. In the rotation sector that is rotated by the motor 5, N on the light source side
As shown in FIG. 3, the 011 rotation sector 4A has a transmission hole 14 and a full absorption surface 15. 1 m1 is placed alternately, and 1 m1 of total reflection is placed on No. 2 rotation sector 4B on the gas side to be measured.
6. The entire absorption surface 15 and the two transmission holes 14 are sunk so that the combination of both rotational sectors is as shown in Table 2.

Reference numeral 6 indicates a /\-fumirror placed between both rotating sectors 4A and 4B; 11 is a parabolic mirror for detecting the light emitted from the spectrometer lO, 91 is a light detection unit such as a one-dimensional array detector ÷ (g, 12 is the main body, 13
is a window provided in the main body 12, and it is preferable that the window has a known transmittance for each wavelength, and that the transmittance for each wavelength is 1% or equal.

In order to measure the concentration and partial pressure of a gas using the device of the present invention, the white light (from 1) is projected onto an ellipsoidal mirror 2 to be focused, and then a parallel light beam is created by an off-axis parabolic mirror 3. ,
The image is projected onto a rotating sector 4A that is rotated by a motor 5. As described above, this rotation sector 4A is provided with transmission holes 14 and total absorption surfaces 15 with a reflectance of 0.5 oz alternately, and the other rotation sector 4B is provided with transmission holes 14. Total absorption surface 15
Since the total reflection surfaces 16 with a light reflectance of 100z are arranged in the combinations shown in Table 2 above, only the light that reaches the transmission hole 14 of the rotation sector 4A once reaches the rotation sector 4.
Reach B.

Therefore, to find the initial strength I (o), rotate sector 4
The combination of the transmission hole 14 of A and the total reflection surface 16 of the rotating sector 4B (Table 2) is located on the optical axis. At this time, the light from the light source 1 is transmitted to the ellipsoidal mirror 2. It becomes a parallel beam of light through the off-axis parabolic mirror 3, passes through the transmission hole 15 of the rotating sector 4A, passes through the half mirror 7, reaches the total reflection surface 16 of the rotating sector 4B, is reflected, and is further reflected by the half mirror 7. The light is focused by the off-axis parabolic mirror 8, enters the spectroscope 10, is split into spectra, and is detected by the photodetector 11 as the light intensity I,,I'
, are detected simultaneously. In this case, in order to be able to measure the light intensity of two wavelengths of light simultaneously in - times of spectroscopy, the reference light and measurement light are positioned on the photodetector (-dimensional array detector). When the wavelength is selected, the zero-order rotational sectors 4A5 and 4B are positioned on the optical axis in a combination (Table 2, 2) that gives a total absorption surface of 15, respectively, and then the light enters the spectrometer 10. Detector 11 has its own dark noise l2 (=I
Z) will be detected. Next, rotating sector 4A
and 4B are both combinations of transmission holes 14 (Table 2 (Dan))
When positioned on the optical axis.

The light from the light source 1 passes through the transmission hole 14 of the rotating sector 4A. /\-
Transmission hole 14 of humirar 61 rotation sector 4B. It passes through the window 13 and reaches the gas to be measured 9, passes through the gas 9, is reflected by the reflective surface 7 provided behind it, passes through the constant gas 9, and returns to the main body 12 from the window 13. The light enters the interior, passes through the transmission hole 14 of the rotating sector 4B, is reflected by the half mirror 6, is reflected by the off-axis parabolic mirror 8, is further separated into spectra by the spectroscope 10, and reaches the photodetector 11. Therefore, the photodetector 11 simultaneously detects the reference light and the final intensity of the M1 constant light 3 and 3. Further, the combination of all absorption surfaces 15 of rotation sector 4A and transmission holes 14 of rotation sector 4B (Table 2 171
)) is located on the optical axis, the photodetector +1 detects the light intensity I4 of backlight noise other than the light source. I4 is detected at the same time.

In this way, the initial intensity, IJI5 noise, final intensity, and light intensity of emitted light (backlight noise) I, , I', , I2
, I3, I'3, I4, I'4 A111
Since constant values can be obtained, the transmittances R,, R2 of the reference light and measurement light can be calculated from these values as shown in Section 1111, and the volume can be calculated using equations (1), (2), and (3). The molar concentration n is also calculated from equation (4) as
+ You can find the partial pressure of a constant gas.

FIG.
This shows an example of an arithmetic circuit for calculating the volume molar concentration n and the partial pressure P from ~I'4.
According to the signal generated from the synchronization circuit 18 which is generated with the rotation of the synchronous circuit 18 and supplied via the decoder 20, the signal is input to one of the sample and hold circuits 21 to 27 via the preamplifier 17 or the preamplifier 17 and the AGC amplifier 19, and the optical The strength is output as 11 to 4. Furthermore, the Kou-strong Electric Works 1 and Works 2 are operated by the arithmetic circuit 31 (II I2
) are performed, and the results of the light intensity I'l and 2 are input to the arithmetic circuit 32 to the AGO control circuit 30, and the output thereof is fed back to the AGO amplifier. - The force tip strength I4 is multiplied by the signal from the base a voltage generator 28 by the arithmetic circuit 33, and further, the arithmetic circuit 36 performs the calculation (I3-I4) with the optical power electrician 3.

Further, the signal from the optical power source '4 is compared with the signal from the base wall voltage generator 28 by the arithmetic circuit 34, and further, the arithmetic circuit 37 calculates (I3 I4). Another 1.0
The transmittance ratio R1 volume molar concentration n is calculated and outputted by the calculation circuit 40 through the g amplifier 39. Further, the obtained volumetric molar concentration n is multiplied by a separately determined temperature T (K) by a multiplier amplifier 41, and a partial pressure P is calculated and outputted via an arithmetic circuit 42.

Further, the above calculations, that is, calculations for determining the volume molar concentration n and the partial pressure P from the light intensities 11 to 4, can also be performed digitally using a microcomputer.

FIG. 5 shows a case where the present invention is applied to measuring the concentration and partial pressure of atmospheric gas near a steel plate in a steel plate annealing furnace.
43 is an annealing furnace, 44 is a bellows connecting the main body 12 and a window 45 provided in the annealing furnace 43, and 46 is a retroreflector.
A flange joint is provided between the reflective surface 7 and the window 48 of the annealing furnace 43, and 47 is a steel plate positioned within the furnace. With this configuration, the concentration and partial pressure of the atmospheric gas in the very vicinity of the steel plate 47 can be measured.

Note that the above explanation was made for the case of one type of gas as the measurement target, but in addition to the other wavelengths absorbed by one other type of gas, including two or more types of rllll.
By using + constant light, the concentrations and partial pressures of two or more gases can be measured simultaneously in the same manner as in the above case.

(Example) Next, an example will be shown in which the CO2 scum concentration was determined to be Jl11 using the apparatus of the present invention. Light 0: (closed temperature 900°
Using a C blackbody furnace, input as reference light 1 = 4.10gm
, a wavelength of 2 = 4.25 gm was used as the measurement light. A measuring cell with a length L = loam is used, and 1. (2) Then, Al11 was determined. 61st X! l is the rotation sector that is the combination of the above ■
This is the output of one-dimensional array detection 2:4 in the case of , and is the spectrum of the initial intensity. In this figure, the wavelength used is input, input 2
The light intensity at 1.1 and 1.1 respectively. It is. Figure 7 shows the output of the one-dimensional array detector when the rotating sectors are the above-mentioned combinations (stages), and is the spectrum of the final intensity. As described above, according to the apparatus of the present invention, a light intensity of 1, 8, or 2 wavelengths can be obtained in one spectral operation.

From the light intensity 11 to
) When the transmittance ratio R was determined using the formula, H=3.73. Further, when the volume molar concentration was determined using the above formula (3), it was found that n = 3.7 mol/l. Furthermore, the above (
4) When calculating the partial pressure of C02 gas using the formula, P=70
It became mmHg.

(Effects of the Invention) As explained above, according to the device of the present invention, the measurement light and the reference light are simply passed through the gas to be measured, regardless of the conditions such as the temperature and pressure of the gas to be measured, and the backlight is constantly illuminated. Accurately measure the concentrations and partial pressures of many different gases simultaneously while removing the effects of noise! Its practical effects are extremely large, as it can be easily constructed, and can be used in many fields.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the configuration of the device of the present invention, Fig. 2 is an explanatory diagram showing the configuration of the rotating sector in the present invention, and Fig. 3 is a diagram showing the total absorption surface, total reflection uj, and transmission hole arranged in the rotating sector. 4 is a diagram showing an example of the arithmetic circuit used in the apparatus of the present invention, FIG. 5 is an explanatory diagram showing the case where the present invention is applied to a copper plate annealing furnace, and FIGS. FIG. 7 is a diagram showing measurement results by the apparatus of the present invention. DESCRIPTION OF SYMBOLS 1... Light source, 2... Elliptical mirror, 3... Off-axis parabolic mirror, 4... Rotating sector, 5... Motor, 6...
... Half mirror 17 ... Reflection surface, 8 ... Off-axis parabolic mirror, 9 ... Gas to be measured, 10 ... Spectrometer, 1
1... Photodetector, 12... Main body, 13... Window, 1
4... Transmission hole, 15... Total absorption surface, 16... Total reflection surface, 17... Preamplifier, 18... Synchronous circuit, I
S...AGC amplifier, 20...decoder, 21~
27...Sample hole I/circuit, 28.28...
Basic voltage generator, 30...AGC control circuit, 31-3
8... Arithmetic circuit, 38... Log amplifier, 40...
・Mo; (first circuit, 41... power p circuit, 42... ji;
i-arithmetic circuit, 43... annealing furnace, 44... bellows, 4
5.48... window, 46... flange joint, 47...
・Steel plate. 4. Applicant for license, agent JF Physician Tomoyuki Yafuki (and one other person)

Claims (1)

[Claims] On the optical axis of the light emitted from the light source toward the gas being measured,
Two rotating sectors that rotate in synchronization with each other are provided, and a half mirror is provided between the rotating sectors to reflect the light reflected by the reflective surface provided at the rear of the gas to be measured. A condensing parabolic mirror, a spectroscope, and a photodetector are provided on the optical axis, and the rotating sector on the light source side is provided with a total absorption surface and a transmission hole, and the other rotating sector is provided with a total absorption surface and a transmission hole. A gas concentration and partial pressure measuring device characterized by having a total reflection surface, a total absorption surface, and a transmission hole.