JPH09113446A - Infrared gas analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an infrared gas analyzer in which the temperature of an infrared detector as a whole is adjusted in a well-balanced manner and in which a temperature abnormality and a failure are reduced by a method wherein a facelike heater which is provided with a self-temperature control function is arranged at the detector. SOLUTION: An infrared gas analyzer is provided with an infrared light source 1, with a filter part 2 in which a semitransparent mirror used to pass infrared rays in a usage wavelength region, a BPF and the like are housed at the inside, with a sample cell 3 which circulates a sample gas, with an infrared detector 4 which analyzes a component in the sample gas and with a facelike heater 5 Which is pasted on the rear surface of the infrared detector 4. As the heater 5, a thin sheetlike heating element, e.g. a heating element whose thin sheet itself is composed of a polymer conductive material, can be used, and its shape and its calorific value can be designated freely. In addition, the heater 5 is provided with a self-temperature control function due to the characteristic of the conductive material itself or due to a combination with a thermostat, and the circumference of the infrared detector 4 can be maintained easily at a constant temperature. Consequently, its temperature can be adjusted in a well-balanced manner as a whole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared gas analyzer used for analyzing gas component concentrations and the like, and more particularly to an infrared gas analyzer capable of keeping the temperature of the detector itself constant.

[0002]

2. Description of the Related Art Carbon monoxide (CO) and nitrogen oxides (NO)
_x )) Infrared gas analyzers used for analyzing various gas concentrations, etc., analyze the infrared absorption spectrum transmitted through the sample cell to determine the gas concentration of the target component or the type of gas in the sample gas. analyse. In such an infrared gas analyzer, as shown in FIG. 3, a filter section 2 and a sample cell 3 are arranged in front of an infrared light source 1, and an infrared detector 4 is arranged in front of the sample cell 3. The detector 4
Is easily affected by changes in ambient temperature, and the zero point is particularly affected and fluctuates. Therefore, the infrared detector 4 cannot perform accurate measurement unless the temperature is kept constant during measurement. Therefore, the temperature control block 13 is attached to the detector 4 and the cartridge heater in the temperature control block 13 is attached. Temperature controller 1 while measuring the temperature of 10 with a sensor 11 such as a thermocouple
2, the temperature of the detector 4 is measured and controlled. In this case, the temperature of the detector 4 is often about 50 ° C.

As a flat heater for keeping the temperature constant, there is known one having a constant resistance value up to a certain temperature and a resistance value rapidly increasing when the temperature exceeds that temperature (a positive temperature sensing element). However, the overall shape is small and the size is limited.
These flat heaters are used for preventing frost in refrigerators and coolers or for protecting overcurrent.

[0004]

In the conventional temperature control method for the detector of the infrared analyzer, a cylindrical cartridge heater and a temperature controller are used, and the temperature is controlled by heating on the circumference. Therefore, a temperature gradient occurs between the surface and the inside, which causes temperature unevenness. In addition, a temperature controller, a temperature sensor, wiring, etc. are required due to the structure, and the cost is high. Since the outside of the object requiring temperature control (infrared detector 4 in the illustrated example) is exposed, it is easily affected by the outside air, and the detector itself also turns on / off the cartridge heater.
There is a drawback that noise is likely to occur during the OFF operation. Further, in recent years, the detector itself has become capable of accurately analyzing even a very small amount of component, but if the detector itself has high sensitivity to the temperature, it is necessary to improve the temperature adjustment accuracy and the temperature adjustment method. .

The present invention has been made in view of the above problems, and provides an infrared gas analyzer in which the temperature of the entire detector is adjusted in a well-balanced manner, and the temperature can be easily adjusted with no abnormal temperature or failure. To aim.

[0006]

In order to solve the above problems, the present invention comprises an infrared light source, a band pass filter for passing infrared rays in a specific wavelength region, a sample cell and an infrared detector. In the infrared gas analyzer, a planar heater having a self-temperature control function is arranged in the infrared detector.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. still,
In order to avoid redundant description, the same components will be described using the same symbols as those used in the related art. FIG. 1 is an overall schematic view of the infrared gas analyzer of the present invention. This infrared gas analyzer is composed of an infrared light source 1, a filter unit 2 containing an infrared ray in the wavelength range used, a harf mirror, a bandpass filter, etc., a sample cell 3 for circulating a sample gas, and a sample. Infrared detector 4 for analyzing the components in the gas, and a planar heater attached to the lower surface of the infrared detector 4.
5 and the like.

As the sheet heater 5, a thin sheet-shaped heating element, for example, one in which the thin sheet itself is made of a polymer conductive material, or a thin wire of a conductive material is attached to a polymer film in a wavy shape. It is possible to use the above, a polymer film printed with a conductive material, a ceramic substrate coated with a conductive paint, and the like. These are sheets and can be freely designed in shape and amount of heat generation, and can be easily attached to the infrared detector 4. Further, these planar heaters 5 can easily maintain a constant temperature around the infrared detector 4 by providing a self-temperature control function by the characteristics of the conductive material itself or by combination with a thermostat. . In particular, a sheet-shaped heater made of a sheet-shaped polymer conductive material and having a self-temperature control function is easy to control so that the temperature rises quickly and reaches a constant temperature.

Further, a sheet-shaped heater formed by printing or applying a conductive material on a polymer film may be constructed so that the coating film separates and the current is cut off due to thermal expansion of the polymer material itself as the temperature rises. it can. Therefore, if the temperature rises excessively, thermal expansion occurs and the thermal runaway is prevented, so that safety management can be performed.

The planar heater 5 can be attached not only to one surface of the infrared detector 4 but also to a plurality of surfaces thereof to uniformly control the temperature of the entire infrared detector 4. In particular, the planar heater 5 can be closely attached to the surface of the detector 4 even if the surface of the detector 4 itself is not flat but has any uneven surface, so that it can be attached and the temperature adjustment efficiency can be improved. It is valid.

FIG. 2 is a vertical sectional view of an infrared gas analyzer of the present invention used for an in-line gas monitor installed in the middle of a gas supply line. In this embodiment, the infrared light source 1 is arranged on one side facing the gas passage 6a provided in the cell block 6, and the infrared detector (pyrosensor) 4 is arranged on the other side. A planar heater 5 is arranged around the pyrosensor 4. Actually, the holes for installing the infrared light source 1 and the pyrosensor 4 have a diameter of 8 to 9 mm (mm) and a length of about 5 mm, but an infrared detector such as such a small pyrosensor 4 has a self-temperature control. A well-balanced temperature control can be performed by using the sheet-shaped heater 5 of the mold.

[0012]

As described in detail above, according to the infrared gas analyzer of the present invention, the temperature control of the conventional infrared detector itself is performed on the circumference by the cartridge heater using an aluminum block or the like. By using a self-regulating type sheet heater, it is possible to control the temperature in a well-balanced manner by controlling the sheet temperature. Further, unlike the conventional case, the temperature controller and the temperature control block are not required, and the temperature can be controlled only by the flat heater, so that the assemblability is good and the cost can be reduced. Furthermore, ON /
Not only does noise not be generated due to the OFF operation, but since there is no need to use a separate temperature controller, abnormal temperature control due to wire breakage, etc. does not occur, there are few failures and safety is high. Further, it is possible to smoothly follow the self-temperature control without causing an overheat.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an infrared gas analyzer according to the present invention.

FIG. 2 is a vertical sectional view of an infrared gas analyzer of a modified embodiment of the present invention used for an in-line gas monitor installed in the middle of a gas supply line.

FIG. 3 is a schematic diagram of an infrared gas analyzer in which an infrared detector having a conventional temperature controller is arranged.

[Explanation of symbols]

 1 Infrared light source 2 Filter section 3 Sample cell 4 Infrared detector 5 Planar heater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Inoue, 2 Higashi-cho, Kichijoin-miya, Minami-ku, Kyoto-shi, Kyoto Inside Horiba Manufacturing Co., Ltd. HORIBA, Ltd.

Claims (1)

[Claims] 1. An infrared gas analyzer comprising an infrared light source, a bandpass filter for passing infrared rays in a specific wavelength region, a sample cell and an infrared detector, wherein the infrared detector has a self-temperature control function. An infrared gas analyzer characterized by arranging a planar heater.