JPS5858615B2 - Infrared gas analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a gas-filled first detection tank and a gas-filled second detection tank are sequentially arranged in series in the measurement optical path and the comparison optical path, and the absorption in the first detection tank is arranged in series. In a gas analyzer that analyzes a sample gas guided to a measurement tank arranged in a measurement optical path based on the difference between the optical energy absorbed by the second detection tank and the optical energy absorbed by the second detection tank, interference in the sample gas is detected. The present invention relates to an infrared gas analyzer that compensates for the influence of components such as water vapor components.

FIG. 1 shows a conventional infrared gas analyzer of this type disclosed in U.S. Pat. No. 3,162,761.

In this FIG. 1, L is an infrared light source, and the infrared light flux emitted from this infrared light source is divided by a chopper CH into a reference light beam (■■) and a measurement light beam Is.

M is a motor that rotates this chopper CH.

As shown in FIG. 2, the chopper CH has an opening 01.
02, the opening 01 forms the measuring beam Is, and the opening 02 forms the measuring beam IV.

The measurement beam Is and the reference beam Iv are connected to this chopper CH.
The measurement light beam Is is formed alternately and periodically intermittently by
is alternately and periodically guided to the measurement tank S, and the reference beam IV to the reference tank (2).

The measurement tank S and the reference tank ■ are each formed integrally,
Light transmission windows R1 and R2 are provided.

A sample gas containing the gas to be analyzed is introduced into the measuring tank S through introduction pipes Z 1 and Z 2 in the direction of the arrow, and a gas that does not absorb infrared rays, such as nitrogen gas, is introduced into the reference tank V. It is enclosed.

Therefore, the measurement light beam IS receives infrared absorption in the measurement tank S depending on the concentration of the gas to be analyzed, while the reference light beam ■V
does not undergo infrared absorption in the reference tank V.

After passing through the measuring tank S and the reference tank V, the measuring beam IS and the reference beam IS are alternately guided to the detector.

In the detector, a first detection tank D1 and a second detection tank D2 are arranged in series in the infrared light path, and each detection tank DI, D2 is filled with the same type of gas as the component gas to be analyzed.

Note that Ra and R4 are light transmission windows, and K is each detection tank DI.
, D2 is a condenser microphone type detection chamber.

The difference in pressure fluctuations in the rain detection tanks DI and D2 based on the difference in infrared absorption with respect to the measurement light beam Is is extracted by the condenser microphone detection chamber K as a capacitance change, that is, a voltage fluctuation, and is indicated as an analysis value for the component gas to be analyzed. Ru.

FIG. 3 shows a light energy absorption characteristic diagram in which the measurement light beam Is is absorbed in the detection tanks DI and D2.

The area AI surrounded by the characteristic line A indicates the amount of optical energy absorbed by the measurement light beam Is by the detection tank D1, and the area A surrounded by the characteristic line I and the characteristic line I
2 indicates the magnitude of optical energy absorbed by the measurement light beam IS by the detection tank D2.

The difference ΔA between the area A1 and the area A2 varies depending on the concentration of the analyte component gas contained in the sample gas, and an electric signal is transmitted from the condenser microphone detection chamber K in accordance with this difference ΔA.

The difference ΔA is always constant when the concentration of the gas to be analyzed is constant.

By the way, when a gas having an infrared absorption region that is the same as or partially overlaps with the component gas to be analyzed coexists in the sample gas (this gas is generally referred to as an interference component).

), and this interference component caused an error in the analysis value of the component gas to be analyzed.

In FIG. 3, characteristic line C shows the state of absorption of infrared rays by this interference component.

However, according to the configuration of the detector as shown in FIG. 1, the absorption of infrared rays (measurement light beam Is) by this interference component is due to the large area of the light energy absorbed in the detection tank D1 (A1) and the detection tank D2. The ratio of the area Al to the area A2, that is, the infrared absorption characteristic of the detection tank Dl and the detection If the infrared absorption characteristics of tank D2 are set appropriately, the area A1
The difference ΔA between the area A2 and the area A2 is always constant.

Therefore, the influence of the interference component can be removed.

As a method for appropriately selecting the ratio between the infrared absorption characteristics of the detection tank Dr and the infrared absorption characteristics of the detection tank D2, these detection tanks D1. Depending on the type of gas filled in D2,
Its concentration and the shape and volume of detection tank D1 ■1 and detection tank D
There is a method of experimentally determining the shape of 2 and the volume v2.

However, according to this method, it is very difficult to strictly determine these relationships, and it is also quite difficult to maintain these conditions for all actual products.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide an infrared gas analyzer of this type that eliminates the influence of interference components with an extremely simple configuration.

This purpose, according to the invention, is to provide a gas-filled first detector which is configured to be irradiated with a measuring beam that has passed through a measuring tank and a comparison beam that has passed through a comparison tank and to allow these measuring beams and comparison beams to pass through. a gas-filled second detection tank configured to be irradiated with the measurement light beam and the comparison light beam that have passed through the first detection tank, and to allow the measurement light beam and the comparison light beam to penetrate therethrough; and the second detection tank. a reflection mechanism arranged to partially reflect the measurement light beam and comparison light beam transmitted through the second detection tank, the reflection mechanism reflects each of the light beams by a desired amount; 1
This is achieved by configuring the sample debris guided to the measurement tank to be analyzed based on the light energy absorbed in the detection tank and the light energy absorbed in the second detection tank.

According to the present invention, at the design stage, the second detection tank is designed and adjusted so that the magnitude of its infrared absorption energy is equal to or smaller than the magnitude of infrared absorption energy in the first detection tank. In this step, the absorption of infrared rays is increased by the action of the reflection mechanism so that the influence of interference components does not appear.

Next, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 4 is a schematic cross-sectional view of an embodiment of the present invention.

In FIG. 4, parts having the same functions as each part of the apparatus shown in FIG. 1 are given the same reference numerals.

In this embodiment, a second detection tank is arranged in series behind the first detection tank D1.

This second detection tank D3 is provided with a light transmission window R5 so as to allow incoming infrared rays to pass therethrough.

Further, at the rear of the second detection tank D3, a movable reflector T is arranged so as to partially reflect the infrared rays that have passed through the second detection tank D3 back to the second detection tank D3. It is composed of

FIG. 5 shows the relationship between the reference tank V, the measurement tank S, and the reflector T, and FIG. 6 shows the relationship between the detector and the reflector T.

Note that the magnitude of the infrared absorption energy in the second detection tank D3 is designed to be smaller than the thickness of the infrared absorption energy in the first detection tank D1.

Furthermore, the measuring light beam Is is again directed to the detection tank D by the reflection plate T.
The light ray that is partially reflected to the third side is hereinafter referred to as a reflected light ray.

Next, the functions of the above configuration will be explained based on FIG.

FIG. 7 shows a light energy absorption characteristic diagram in which the measurement light beam s is absorbed in the detection tanks DI and D3.

The area A1 surrounded by the characteristic line A indicates the amount of light energy absorbed by the measurement line Is by the detection tank D1 as described above, and the area A3 surrounded by the characteristic line A and the characteristic line I is the detection area The magnitude of the light energy absorbed by the measurement light beam Is by the tank D3 is shown.

At this time, area A1>area A3.

In this state, the area abc and the area bcfg affected by the absorption of the interference component are not equal, and therefore, even if the concentration of the gas to be analyzed is constant, the area AI and the area A3 will vary depending on the amount of the interference component. The difference between changes.

Therefore, in the present invention, a reflection plate T is inserted to return a portion of the measurement light beam Is to the detection tank D3 side again.

The characteristic line E is the absorption characteristic line of the detection tank D3 for this reflected light, and the area A4 surrounded by the characteristic line E and the characteristic line 2 is the amount of light energy that the reflected light is absorbed in the detection tank D3. be.

Therefore, the infrared absorption capacity of the detection tank D3 is increased by an amount corresponding to this area A4, and the overall area is A3.
and the area A4 (A3+A, =A.

shall be.

) will absorb energy equivalent to .

By adjusting the insertion amount of the reflection plate T, the area abc and the area bcih are set to be equal.

By doing this, when the concentration of the component gas to be analyzed is constant, the difference between the area A1 and the area A5 is always constant regardless of the amount of the interfering component, and the influence of the interfering component can be removed. I can do it.

FIG. 8 shows another embodiment of the reflector T, and shows the relationship between the reflector T and the detector.

In addition, in the above description, regarding the reflected light, the detection tank D3
Although attention has been focused only on the optical energy absorbed in the detection tank D1, in reality, this reflected light also receives absorption of optical energy in the detection tank D1.

However, since the amount of light energy absorbed is actually very small, the explanation is omitted to make the explanation of the present invention easier to understand.

FIG. 9 is a schematic diagram of another embodiment of the present invention.

In FIG. 9, parts having the same functions as those in the embodiment shown in FIG. 4 are given the same reference numerals.

In this embodiment, the reflection plate A light shielding plate Q is provided so as to be insertable in the optical path between the tank D3 and the tank D3.

The surface of the light shielding plate Q that the light beam strikes is colored, for example, black so as to absorb the light beam, and blocks the light beam that has passed through the second detection tank D3 from reaching the reflection plate X.

Figure 10 shows the relationship between the measurement tank S, reference tank V, light shielding plate Q, and reflection plate X, and Figure 11 shows the relationship between the detector D, the light shielding plate Q
and the relationship between the reflector X and the reflector X are shown.

As shown in FIGS. 10 and 11, the light shielding plate Q is movable in the direction of the arrow, and for example, light rays in an area W indicated by the dotted line are reflected by the reflecting plate X as reflected light.

In the above embodiments, the reflection plate T and the light shielding plate Q are configured to be movable, and the amount of reflected light is adjusted by changing the insertion amount of the reflection plate T and the light shielding plate Q into the optical path. A reflected light beam having a characteristic line E such that the area abc and the area bcih are equal is selected.

However, the present invention is not limited to such embodiments; for example, the second detection tank D3 may be provided with a reflection plate in advance that can reflect a reflected light beam that may cause the second detection tank D3 to absorb light energy as shown by the characteristic line E. Prepare this reflector plate in the second detection tank D3. It can also be placed in the optical path behind the

This is because the present invention is based on the technical idea that it is only necessary that the light energy shown by the characteristic line E be absorbed in the second detection tank D3 by the light beam reflected by the reflection mechanism.

Therefore, it does not matter whether the reflection mechanism is movable or not.

FIG. 12 is a schematic sectional view of still another embodiment of the present invention based on this technical idea.

In this embodiment, a reflection plate F provided with an opening G is fixedly disposed on the optical path behind the second detection tank D3.

FIG. 13 shows such reflectors F+, F2. F3. F
4 and a detector, each of the reflecting plates F+, F2, and FatF4 is provided with, for example, circular openings G+, G2, Ga, and G4 having different areas, respectively.

That is, in this embodiment, a large number of reflecting plates each having openings with different areas are prepared in advance, and in the adjustment stage, the absorption of light energy shown by the characteristic line E is determined first. 2. Select a reflector plate, for example, reflector F/3, which can provide a reflected light beam that causes the detection tank D3 to rise, and insert this reflector F3 into the screw hole N1. N2, Ns
, N4 to a member not shown in the figure.

Thus, the amount of reflected light can be selected to a desired amount and the effects of interference can be compensated for.

FIG. 14 is a schematic diagram of a main part of still another embodiment of the present invention.

This embodiment corresponds to the relationship between the reflector X and the light-shielding plate Q in the embodiment shown in FIG. Board Q1. Q
2. Q3°G4 is fixedly arranged.

However, the light shielding plates Ql, Q2. Q3. For example, circular openings E+ and E each have a different area in Q4.
2°F3. F4 is provided respectively.

Therefore, in this embodiment as well, a large number of light shielding plates having openings with different areas are prepared in advance, and in the adjustment stage, a light shielding plate, such as light shielding plate Q4, that can provide a desired amount of reflected light is selected.

As explained above, in the present invention, the first detection tank D1 and the second detection tank D are provided in the measurement optical path and the comparison optical path.
3 are arranged in series one after another, and both rain detection tanks Ih and Ds are configured to transmit infrared rays, and at the rear of the second detection tank, a portion of the infrared rays transmitted through the second detection tank is transmitted to the second detection tank. A reflection mechanism that can reflect the light again is provided on the detection tank side, and this reflection mechanism selects the amount of reflected light to a desired amount, appropriately selects the magnitude of the infrared absorption energy generated in the rain detection tank, and removes interference components. Since the configuration is configured to remove the influence, it is possible to compensate for the influence of interference components with high precision using an extremely simple configuration.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional infrared gas analyzer;
The figure is a schematic diagram showing the relationship between the chopper, the reference tank, and the measurement tank, Figure 3 is an infrared absorption characteristic diagram of the detector, Figure 4 is a schematic configuration diagram of an embodiment of the present invention, and Figure 5 is a diagram showing the relationship between the chopper and the reference tank and measurement tank. Schematic diagram showing the relationship between the reference tank, measurement tank, and reflector, No. 6
The figure is a schematic diagram showing the relationship between the detector and the reflector, Figure 7 is an infrared absorption characteristic diagram of the detector, and Figure 8 is the relationship between the reflector and detector using another embodiment. Schematic diagram, FIG. 9 is a schematic diagram of another embodiment of the present invention, FIG. 10 is a schematic diagram showing the relationship among the reference tank, measurement tank, reflector plate, and light shielding plate, and FIG. 11 is the detector, FIG. 12 is a schematic diagram showing the relationship between a reflector and a light shielding plate, FIG. 12 is a schematic diagram of still another embodiment of the present invention, FIG. 13 is a schematic diagram showing the relationship between the reflector and the detector, and FIG. 14 is a schematic diagram showing the relationship between the reflector and the detector. FIG. 7 is a schematic diagram of a main part of still another embodiment of the present invention. S...Measurement tank, ■...Reference tank, D...
...Detector, DI, D3...Detection tank, R3
, R4, R5... Light transmission window, Tt Xs Fl
t ” 2 t F 3 , F 4...
Reflector, Q, Q+, G2. G3, G4...
Light blocking plate.

Claims (1)

[Scope of Claims] 1. A gas-filled first detection tank configured to be irradiated with the measurement light beam that has passed through the measurement tank and the comparison light beam that has passed through the comparison tank, and to allow the measurement light beam and the comparison light beam to pass through; The measurement light beam and the comparison light beam transmitted through the first detection tank are irradiated with a gas-filled second detection tank configured to allow the measurement light beam and the comparison light beam to pass through the second detection tank. and a reflection mechanism arranged to partially reflect the measurement light beam and the comparison light beam toward the second detection tank, and the light energy absorbed in the first detection tank and the second detection tank can be reflected. An infrared gas analyzer characterized in that the sample gas guided to the measurement tank is analyzed based on the optical energy absorbed by the infrared gas analyzer. 2. In the infrared gas analyzer according to claim 1, a movably configured reflecting plate is used as the reflecting mechanism, and by changing the amount of insertion of this reflecting plate into each of the light beams, An infrared gas analyzer characterized in that it is configured to obtain a desired amount of reflected light. 3. In the infrared gas analyzer according to claim 1, the reflection mechanism includes a light shielding plate and a reflecting element that are optically arranged in series, and the light shielding plate is configured to be movable, and each light beam is An infrared gas analyzer characterized in that the infrared gas analyzer is configured such that a desired amount of reflection of each of the light beams can be obtained by changing the amount of insertion of the light shielding plate into the path. 4. In the infrared gas analyzer according to claim 1, a reflecting element configured in advance to be able to reflect a desired amount of each light beam is used as the reflecting mechanism, and this reflecting element is connected to each optical path. An infrared gas analyzer characterized by a fixed arrangement.