JPS6032594Y2 - gas analyzer - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement of a gas analyzer that measures the concentration of a component of interest by transmitting light through a measurement cell filled with a gas to be measured and detecting the amount of absorbed light. .

An object of the present invention is to provide a gas analyzer with less light loss in the optical system and with stable accuracy.

FIG. 1 is an explanatory diagram of the configuration of main parts of a conventional infrared gas analyzer.

In the figure, the measuring cell 4' is cylindrical, and its inner wall 4
3' has a structure that reflects light, and both ends are windows 44' and 45' that transmit light.

The side wall of the measurement cell 4' is provided with an inlet 41' and an outlet 42' through which the gas to be measured flows.

A light source 1 and a sector 2 for blocking light from the light source are provided on the window 44' side of the measurement cell 4', and the sector 2 is rotated at a constant speed by a sector drive source 3.

On the other hand, a cone-shaped condenser 7, an optical filter 5, and a sensor 6 are provided on the window 45' side.

The optical filter 5 has a spectral characteristic that transmits the absorption wavelength region of the measurement component contained in the gas to be measured and cuts other regions.

In the gas analyzer having such a configuration, light is intermittently emitted from the light source 1 into the measurement cell 4', and the sensor 6 receives the straight light L/2 and the reflected light L'.

(light that is transmitted while being reflected by the inner wall 43') reaches and is detected.

If the amount of light from the light source 1 is stable and constant, the signal detected by the sensor 6 will be obtained as a function of the concentration of the component to be measured, that is, as a concentration signal itself.

The problem with the gas analyzer is that the light detected by the sensor 6 includes reflected light V1.

That is, since the reflected light l/, is repeatedly reflected on the inner wall 43', a loss in the amount of light is inevitable, and it is also affected by the dirt on the inner wall 43'.

In particular, since the dirt on the inner wall 43' changes over time, this poses a problem in terms of the measurement accuracy of the gas analyzer.

FIG. 2 is an explanatory diagram of the configuration of a gas analyzer according to the present invention that solves the above problems.

In FIG. 2, the same reference numerals as in FIG. 1 indicate the same structures and functions, and the explanation thereof will be omitted here.

The structural feature of the gas analyzer according to the present invention is that the main part is composed of a measuring cell 4 whose diameter D1 is larger than the diameter D2 (diameter of the light projection surface) of the light source 1, and a window 44 through which light enters. , in that an annular light quantity diaphragm 8 is installed.

With the above configuration, the number of times the reflected light is reflected can be reduced.

To help understand this effect, a conventional measuring cell 4' is shown in dotted lines in FIG.

Now, looking at the light Lt from the light source 1 (the light projected diagonally upward in the figure), in the case of the conventional measurement cell 4', the reflected light L'1 is reflected at least twice on the inner wall 41'. However, in the case of the measurement cell 4, the reflected light reaches the sensor 6 after one reflection.

In this way, in the gas analyzer of the present invention, the number of reflections of the reflected light reaching the sensor 6 is small.

From the point of view of the amount of light reaching the sensor 6, it is advantageous not to have the diaphragm 8, but there is no problem in comparison with the conventional example.

According to the inventor's experiments, the sensor is equipped with a measurement cell 4 having a diameter D1 50% larger than that of the conventional example, and an annular light quantity diaphragm 8 having a through hole with the same diameter as the diameter D1 of the light source 1 is installed. The amount of light reaching 6 was about twice as much.

Precision is also improved by installing the diaphragm 8.

In the configuration shown in FIG. 2, the light that is blocked by the annular diaphragm 8 is light that has a large incident angle with respect to the window 44 surface.

Such light reaches the sensor 6 after being reflected many times on the inner wall 43.

Therefore, the light is strongly influenced by dirt on the inner wall 43 and contains error factors, making it undesirable light in terms of measurement accuracy.

By blocking such light with the annular light aperture 8, accuracy can be improved.

As explained in detail above, according to the gas analyzer of the present invention, there is little light loss in the optical system and it is possible to obtain a highly accurate measurement signal.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the main parts of a conventional gas analyzer;
The figure is an explanatory diagram of the configuration of main parts of a gas analyzer according to an embodiment of the present invention. 1...Light source, 2...Sector, 3...
...Sector drive source, 4...Measurement cell, 43.
...Inner wall, 5...Optical filter, 6...
...Sensor, 7...Concentrator, 8...
・Annular aperture.

Claims (1)

[Scope of utility model registration request] In a gas analyzer, the concentration of the component of interest is measured by transmitting light into a measurement cell filled with a gas to be measured and detecting the amount of absorption of the transmitted light. a cylindrical measurement cell having a window that transmits light; a light source that emits a non-parallel light beam that passes through the measurement cell;
an annular light amount diaphragm provided on the entrance window surface of the measurement cell to narrow down the luminous flux irradiated from the light source; the measurement cell has a diameter larger than the diameter of the light projection surface of the light source; A gas analyzer characterized in that the diaphragm is configured to have a through hole that is the same in diameter as the projection surface of the light source.