JPS6219736A - Infrared ray type gas analyzer - Google Patents

Abstract

PURPOSE:To enable measurement of the density of a measuring component without changing the constituent component of an analyzer even in case of the density of the measuring compo nent varying largely on each sample gas by providing the measuring cell to store an optical path body having at least a pair of infrared ray transmitting windows. CONSTITUTION:An attachable and detachable filter transmitting the wavelength to represent the absorption wavelength of the measuring component in a sample gas is fitted to the infrared ray transmitting windows 23, 23 of a measuring cell 12, in case of the density measurement of CO2 in the exhaust gas before and after combustion, for instance, in case of the measuring component in the sample gas being one and the density of the measuring component thereof varying largely on each sample gas. The density of the measuring component in the sample gas is then measured by rotating an optical path body 11 with the operation of a motor 14. In this case, the detecting signal of an infrared ray which passed through the closed cylindrical member 19 having the intermediate length that the gap with the inner wall of the measuring cell 12 becomes narrow secondly is used as the measuring signal in case of the density of the measuring component being high, and in case of low, the detecting signal of the infrared ray having passed through the shortest closed cylindrical member 20 that the gap with the inner wall of the measuring cell 12 becomes widest is used as the measuring signal.

Description

Detailed Description of the Invention (a) Industrial Application Field This invention relates to an infrared gas analyzer that continuously measures the concentration of a component to be measured in a sample gas such as exhaust gas having an absorption wavelength in the infrared region. relates to an infrared gas analyzer suitable for measuring the concentration of a measurement component that varies greatly depending on the sample gas.

(B) Conventional technology As shown in Fig. 5, in a conventional infrared gas analyzer, light from a light source (1) is transmitted through a tube equipped with a sample gas introduction path (a) and a sample gas discharge path (3). It is configured so that it passes through the shaped measurement cell (4) and enters the infrared detector (5).
The light from the light source (1) is attenuated by absorption of infrared rays as it passes through the measurement cell (4). A disc-shaped sector (6) is provided horizontally rotatably between the measurement cell (4) and the infrared detector (5), and the sector (6) receives light from the light source (1). Optical filter for wavelength selection of light (7
1f8] are provided. Note that these filters (swords (8) consist of a measurement filter that transmits a wavelength representative of the absorption wavelength of the measurement component, and a comparison filter that is unrelated to the measurement component. 6)
is rotated by the motor (9), and both optical filters (sword (8)
) is arranged alternately on the optical path from the light source (1), and the 9 degrees of the measured component is detected from the difference in the amount of light that occurs.

(c) Problems to be solved by the invention However, with the above analyzer, the concentration of one component to be measured in the sample gas varies greatly from sample gas to another, or the concentration of multiple components to be measured in the sample gas is large. If different, the measurement cell (4) is adjusted depending on the concentration of the component to be measured each time the measurement is performed.
There was the hassle of having to replace the measuring cell with a shorter or longer measuring cell. Also, since the sector (6) is inserted between the measurement cell (4) and the infrared detector (5), the sector (6) is inserted between the measurement cell (4) and the infrared detector (5). A gap had arisen. Therefore, especially when the concentration of the component to be measured in the sample gas is low, the measured concentration is affected by the fluctuation in the components of the air present in the gap, resulting in measurement errors.

This invention was made in view of the above circumstances, and it is possible to use an analyzer even when the concentration of one measuring component in a sample gas varies greatly from sample gas to sample gas, or when the concentrations of multiple measuring components in a sample gas differ greatly. An object of the present invention is to provide an infrared gas analysis δt that can accurately measure the concentration of each component to be measured without replacing the component parts.

(d) Means for Solving the Problems The present invention is an infrared type gas analyzer, in which a plurality of longitudinal members having different lengths capable of transmitting infrared rays in the longitudinal direction are arranged on the same plane and at the central part thereof in the longitudinal direction. A hollow disk body is provided with at least one optical path body formed so as not to intersect with each other, a sample gas introduction path and a sample gas discharge path, and has at least a pair of infrared transmitting windows at symmetrical positions of l111, and houses the optical path body. A rotating shaft that sandwiches the center of the intersection between the measurement cell and the optical path body and extends rotatably outside the measurement cell approximately coaxially with the center axis of the measurement cell in a direction substantially orthogonal to the direction of intersection; at least one pair of light sources and infrared rays that are attached to the outer wall of the body of the measuring cell and form an optical path that passes through the infrared ray transmission window and that passes through each longitudinal member when the optical path is rotated; The infrared transmitting window of the measurement hill is configured so that a filter in the sample gas can be detachably attached, and both end faces of the longest longitudinal member of the optical path body are arranged so that they are independent of the measurement component in the sample gas. A filter is configured to be removably attached, and a filter for transmitting a wavelength representative of the absorption wavelength in the sample gas is configured to be detachably attached to both end surfaces of each of the other longitudinal members of the optical path body. This is what I did.

(E) Function According to the present invention, when the optical path body is rotated, the distance between both ends of each longitudinal member and the light source and the infrared detector changes, whereby one or more measurement components in the sample gas change. This method is designed to measure the concentration of a component to be measured when the measured concentration varies greatly depending on the sample gas.

(F) EXAMPLES The present invention will be described in detail below based on examples shown in the figures. Note that this invention is not limited to this.

In Figure M1 and Figure 2, the infrared gas analyzer (G)
) C, optical path body (11J, 1llll constant t'/lz
021, rotation @03), a motor 04), a light source (15), and an infrared detector (161).

The optical path body (1υ) consists of three sealed cylindrical members of different lengths each having an infrared transmitting window at both ends and filled with inert gas. Each sealed cylindrical member 08)'
(Both end surfaces of ICo (21 are the above member 08)) (19
) A different filter (not shown), which will be described later, is attached to the attachment/detachment ridge. In addition, nitrogen (N2) is mentioned as a preferable example of the said inert gas. Further, the optical path body (11) includes the member (18)
In addition to a91■, a columnar member that can transmit infrared rays in the longitudinal direction may be used. Preferred examples of the material for this columnar member include calcium fluoride.

The measurement cell a'2J houses the optical path body (11),
It consists of a hollow disc body, and a sample gas introduction path &+1 and a sample gas discharge path opening into the measurement cell surface are attached to the body wall, and a pair of infrared transmitting windows are installed at symmetrical positions on the body wall. (to) is provided. Each infrared transmitting window @ is configured such that a filter (not shown), which will be described later, is removably attached.

The rotation axis 03) is rotatably extended out of the measurement cell plane substantially coaxially with the center axis of the measurement cell (121), and is oriented substantially perpendicular to the direction of intersection while sandwiching the center of the intersection of the optical path body (11). The motor (14) is attached to the extending end of the rotating shaft (03).

The light source f15] and the infrared detector (+61 are configured to form an optical path that passes through the infrared transmitting window (to) (to) and passes through each longitudinal member Q8LO9 when the optical path body (11) is rotated. It is attached to the outer wall of the body of the measurement cell f121.

The longest one of the sealed cylindrical members (18) [ll'D■ is formed in such a length that the gap with the inner wall of the measurement cell 0z is almost zero.

Next, how to use the above analyzer will be explained.

Note that the longest sealed cylindrical member (18) is used as a reference with no sample gas on the optical path.

First, when there is only one component to be measured in the sample gas and the concentration of that component varies greatly depending on the sample gas, for example, when measuring the concentration of 002 in the exhaust gas before and after combustion, the measurement cell a
A filter that transmits a wavelength representative of the absorption wavelength of the measurement component in the sample gas is attached to the infrared transmission window @ (to) of '2J. Then, the concentration of the measurement component in the sample gas is measured by rotating the optical path member (Ill) by the operation of the motor M).At this time, if the concentration of the measurement component is high, the gap between the measurement cell surface and the inner wall The detection signal of the infrared rays passing through the middle-length sealed cylindrical member a9 which becomes the second narrowest is used as the measurement signal, and when the concentration of the measurement component is low, the gap between the measurement cell surface and the inner wall is the widest. The infrared detection signal that has passed through the shortest sealed cylindrical member (2) is used as the measurement signal.

Next, when there are two components to be measured in the sample gas and the concentrations of these components are significantly different, for example, when measuring low concentration CO and high concentration CO2 in combustion exhaust gas, the longest closed cylinder is used. A filter unrelated to the two components is used for the infrared transmitting window a of the member (18), and a filter representative of the absorption wavelength of carbon dioxide (CO2) is used for the infrared transmitting window zero of the intermediate-length sealed cylindrical member. A filter representative of the absorption wavelength of -carbon oxide (Co) is attached to each infrared transmitting window 07) of the shortest sealed cylindrical member (2). And the motor (1
4) By rotating the optical path body (11J),
Measures the concentration of the component to be measured in the gas. At this time, to measure the concentration of C02, an intermediate length closed cylindrical member a! The detection signal of the infrared rays which passed through 1 is used as the measurement signal, and the detection signal of the infrared rays which passed through the shortest sealed cylindrical member 2 is used as the measurement signal to measure the concentration of CO.

As described above, even if the measured component in the sample gas is single and its measured concentration varies greatly depending on the sample gas, or even if the measured component in the sample gas is two components and their measured concentrations differ greatly, the optical path body (1 υ The concentration of the component to be measured in the sample gas can be measured simply by rotating the .In addition, since there is no air on the optical path from the light source 05) to the infrared detector color, it is possible to measure the concentration of the component to be measured in the sample gas. Measurement errors in concentration will no longer occur.

FIG. 3 shows another embodiment, in which two sets of light sources (15a) and infrared detectors (16a) are provided as in the first embodiment. This can be used for measurements where there are two components to be measured in the sample gas and the concentrations of each component vary greatly from sample gas to sample gas. In this case, there may be three or more sets of light sources and infrared detectors.

FIG. 4 is a diagram showing another embodiment, in which the measurement cell (
12b), for example, three optical path bodies (llb) are provided in a rotatably stacked state, and each optical path body (11
In correspondence with b), 311 light sources (1
5b) and an infrared detector (16b).

This can be used for measurements when the sample gas has multiple components to be measured and the concentrations of the components to be measured in the sample gas vary greatly.

In addition to the above, four or more sealed cylindrical members may be used to measure multiple components in the sample gas, and the gap between both ends of the longest sealed cylindrical member and the inner wall of the measurement cell may be minimized. When the longest sealed cylindrical member slides on the inner wall of the measurement hill and rotates, the rotation of the optical path body draws the sample gas into the measurement cell and causes the sample gas to be discharged outside the measurement cell. This eliminates the need to provide a pump for introducing sample gas into the measurement cell.

(G) Effects of the Invention According to this invention, even when the concentration of one or more measurement components in a sample varies greatly depending on the sample gas, the concentrations of the plurality of measurement components in the sample gas vary greatly depending on the measurement component. Even in cases where the analyzer is in use, the concentration of each component can be easily and accurately measured without replacing any component parts of the analyzer.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of this invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a view corresponding to FIG. 1 showing another embodiment of this invention, and FIG. 2 shows another embodiment of the present invention, and FIG. 5 is a perspective view of a conventional example. (I))... Infrared gas analyzer, (Ill
(11a) (11b) ------- Optical path body,
G21 (12a) (12b)-=-mll constant cell, 03) (13b)... Rotation axis, G4
) (14b)...Motor, 051 (15a
) (15b) --light m, (16) (16a
) (16b) --Infrared detector, 08)8■・
... Sealed cylindrical member (longitudinal member), 21) ...
...Sample gas introduction path, (branch)...Sample gas discharge path, (branch)...Infrared transmission window. Figure 2

Claims (1)

[Claims] 1. At least one optical path body formed by a plurality of longitudinal members having different lengths that can transmit infrared rays in the longitudinal direction and intersecting each other at the center of the longitudinal direction, a sample gas introduction path, and a sample gas discharge A hollow disc body with a passageway, having at least a pair of infrared transmitting windows at symmetrical positions on its body wall, and a measuring cell that houses the optical passageway body, and a measurement cell that holds the center of the intersection of the optical passageways and is substantially perpendicular to the direction of intersection thereof. a rotating shaft rotatably extending outside the measuring cell approximately coaxially with the central axis of the measuring cell; a motor provided outside the measuring cell for rotating the rotating shaft; at least one pair of light sources and an infrared detector forming an optical path that passes through the infrared transmitting window and transmits through each longitudinal member when the optical path is rotated; It is configured so that a filter that transmits a wavelength representative of the absorption wavelength of the sample gas can be removably attached, and filters unrelated to the measurement component in the sample gas can be attached and detached to both end faces of the longest longitudinal member of the optical path body. The infrared gas type is configured such that filters for transmitting wavelengths representative of the absorption wavelengths in the sample gas can be detachably attached to both end faces of each of the other longitudinal members of the optical path body. Analyzer.