JPS62217139A - Measuring instrument for gas concentration - Google Patents

Abstract

PURPOSE:To stabilize a measured value by condensing dew in a chamber which contains an optical path of measurement by cooling fins and making the humidity constant in the chamber. CONSTITUTION:The outside air 15 is cooled successively by cooling fins 16 provided in the middle of a pipe 20 to reach saturated steam pressure. Excessive steam is condensed into dew on the fins, the temperature measured by a temperature sensor 22 is monitored on a temperature measuring instrument 23, and the dew point is controlled by a temperature controller 14 through an electronic cooler 21. Objective gas in the chamber 17 wherein the admitted gas is controlled by the cooling fins 16 to constant temperature and 100% humidity is absorbed and reference gas 6 is also absorbed to find the gas concentration. The temperature and humidity of the air in the chamber 17 are controlled, so the influence of steam is superposed upon the measured gas concentration by a constant quantity, so the quantity of the superposition is inputted to a computer 1, so that the influence of steam is removed stably even if the admitted outside air 15 varies in humidity.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a method for determining gas 11:4 degrees from the amount of infrared absorption at the characteristic absorption line of a specific gas. In order to eliminate the shadow 9 of measured value fluctuations due to fluctuations in absorption due to water vapor existing near the absorption line of interest, the moisture in the chamber containing the measurement optical path [
- By condensing with cooling fins and making it constant, the humidity is kept constant and the measured values are stabilized.

[Industrial application field]

The present invention relates to improving the measurement accuracy of a gas sensor, and particularly to an apparatus configuration for eliminating measurement errors caused by water vapor.

Gas sensors use strong absorption lines r in the infrared region, so high sensitivity is expected, but each gas has hundreds to thousands of absorption lines, so it is best to use the target absorption line of the target gas. Even if an attempt is made to do so, the water vapor absorption line exists near the target absorption line, which causes an error in the measured gas concentration. Therefore, a method is required to keep the humidity constant and reduce the amount of water vapor.

[Conventional technology]

The structure of a conventional gas sensor a'lc is shown in FIG.

In the figure, 1 is a computer, 2 is a laser power supply, 8 is a laser,
4, lens 95 is a beam splitter.

6 is a reference gas cell, 7 is a condenser lens, 8 is a detector, 9 is a long optical path optical system, and IO is a condenser lens.

11 is a detector, 12.12' is a signal detection circuit.

18 is a comparator, and 19 is an IUe display circuit.

As shown in the figure, a comparison 1 (known gas 1 rainbow x measurement side signal/reference side signal) to determine the continuous use of gas.

[Problem that the invention seeks to solve]

Conventional gas sensors have a TL structure in which the long optical path cell section is open to the atmosphere, so there is a problem that the amount of water vapor absorbed at the target absorption line changes as the atmospheric humidity changes, causing the measured concentration value to change. ? It was happening.

[Means for solving problems]

Figure 1 shows the atmospheric humidity of the present invention? This is a tl diagram to keep it constant. 20 is a vibrator for introducing the atmosphere 15. 15 is the atmosphere, and cooling fin 1 installed in the middle of 20
6, it is sequentially cooled and reaches the saturated water vapor pressure. Excess water vapor condenses on the fins ↓ The dew point is monitored by a thermometer 28, which measures the temperature r measured by a temperature sensor 22, and is controlled by, for example, an electronic cooler 21 in temperature control 2;14.

[For production]

In the sensor of the present invention, the temperature of the introduced atmosphere 4 is controlled to be 0.degree. C. and the humidity is 100, for example, and since only the atmosphere 4' is in the measurement optical path, the influence of water vapor is always constant.

As a result, even if the humidity of the introduced atmosphere 4 changes, the measured value is not affected and the measured value is stabilized. Furthermore, if you measure the shadow 1' of water vapor by 6 degrees under the condition of 0C9100*, and correct it by adding or subtracting the measurement result, you can get an absolute value of 8 degrees, which eliminates measurement errors.

〔Example〕

FIG. 2 is a configuration diagram of a gas sensor according to a first embodiment of the present invention.

In the figure, 1 is a combination kneader that controls the signal system of the sensor, 2 is a sensor power supply, 3 is a laser light source, 4 is a lens, 5 is a beam splitter, 6 is a reference gas cell, 7 is a condenser lens, 8 is a detector, 9 10 is a long optical path optical system for measurement, 10 is a condensing lens,
11 is a detector, 12.12' is a signal detection circuit, 13 is a comparator, 14 is a temperature controller, 15 is an introduced atmosphere, 16 is a cooling fin, 17 is a chamber to cover 9, 18 is an exhaust atmosphere, 19
is determined by the concentration display.

The introduced atmosphere 15 has a constant temperature and humidity of 100 using cooling fins 16.
The gas concentration [r is calculated from the absorption by the target gas in the chamber 17 and the absorption by the reference gas 6. According to this embodiment, since the temperature and humidity of the atmosphere inside the chamber are controlled (the effect of water vapor on the measured gas concentration is a certain amount), this superposition ff1v
By inputting the information into a computer 6, it is possible to stably remove the influence of water vapor even if there are fluctuations in the humidity of the introduced atmosphere 15.

〔Effect of the invention〕

According to the present invention, is the target gas-blade affected by changes in atmospheric humidity? What did you receive? Since the humidity is kept constant,
It is possible to remove factors that cause fluctuations in measured values. Furthermore, if the wet fart content is constant, the measured value can be easily corrected, which has the effect of improving the absolute measurement degree.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the present invention in detail, and FIG. 2 is a configuration diagram of a gas sensor showing an embodiment of the present invention. FIG. 8 is a configuration diagram showing a conventional example. Figure 1c? 1 is a combination unit, 2 is a laser power supply,
8 expanded laser light source, 4 lens, 5 beam splitter,
6 is a reference gas cell, 7 is a condensing lens, 8 is a detector, 9 is a long optical path optical system, 10 is a condensing lens, 11 is a detector, z2
．． j;:821 is the signal detection circuit, 1B is the ratio! 2 vessels, 14
is the temperature HA5゜15 is the introduced atmosphere, 15' is the dehumidified atmosphere, L6
17 is a cooling fin, 17 is a chamber, and 18 is a discharged atmosphere. 19 is a concentration display, 20 is an introduction vibrator, 21 is an electronic cooler, 22 is a temperature sensor, and 23 is an a++ warmer. '$1m -zu(:J1 Tomoe Aosu Figure 2

Claims (1)

[Claims] In a measuring device that has a variable wavelength light source and an optical system that propagates light from the light source and determines gas concentration from the amount of infrared absorption absorbed by a specific absorption line of a specific gas, there is provided a chamber 17 that covers a measurement optical path; A gas concentration measuring device characterized in that it has a fin 16 that cools the fin 16 to a constant temperature, a cooler 21 that cools the fin 16, and a temperature regulator 14 that controls the temperature to a constant temperature at an inlet.