JPH07120389A - Gas analyzer - Google Patents

Abstract

PURPOSE:To eliminate measuring error and to prevent the fault of an analyzer by a method wherein a purge gas whose dehumidifying performance is high is introduced into a semipermeable-membrane drier. CONSTITUTION:A part of a sample gas which is introduced from a semipermeable-membrane drier 1, is introduced into a zero-gas purifier 7 for a gas for zero calibration. The gas is heated and dried by a gas heater for zero calibration. The gas is heated and dried by a heater provided in the zero- gas purifier 7, an error component around a sensor 10 for an analytical part 6 is removed, and it is then introduced into an outer tube 1b for the semipermeable-membrane drier 1. On the other hand, when the sample gas is passed through a semipermeable-membrane tube 1a, it is dehumidified by a dry gas which is introduced into the outer tube 1b. The dehumidified sample gas is guided to a measuring cell 9 situated in the analytical part 6, it is irradiated with infrared rays R here, their transmitted rays are detected by the sensor 10 situated in the analytical part 6, and the component of the sample gas is analyzed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas analyzer used for analyzing components of the atmosphere, flue gas and the like.

[0002]

2. Description of the Related Art Conventionally, the measurement gas is dehumidified in a gas analyzer by flowing the measurement gas into a semipermeable membrane tube and flowing dry air (hereinafter referred to as purge gas) outside the semipermeable membrane.

FIG. 3 shows a schematic configuration of a conventional gas analyzer. In FIG. 3, 1 is a semipermeable membrane dryer, 2 is a sample gas inlet, 3 is a purge gas inlet, 4 is a sample gas outlet, 5 is a purge gas outlet, 6 is an analyzer, and a, b, c, d. e, f, g
Is a gas path, A is a gas branch point, and B is a gas confluence point. Further, FIG. 4 shows a semipermeable membrane dryer, where 1a is a semipermeable membrane tube and 1b is an outer tube.

Next, the operation of the conventional gas analyzer shown in FIG. 3 will be described. The sample gas sucked by the suction device (not shown) is introduced from the sample gas inlet 2 of the semipermeable membrane dryer 1 via the gas path a. When the sample gas passes through the semipermeable membrane dryer 1, it is dehumidified by the purge gas introduced through the gas path f. The semipermeable membrane dryer 1 is configured as shown in FIG. When the sample gas introduced into the semipermeable membrane tube 1a is passed through the semipermeable membrane tube 1a, the purge gas introduced from the purge gas inlet 3 and flowing in the outer tube 1b dehumidifies the sample gas through the semipermeable membrane tube 1a. Is done. Then, the dehumidified sample gas is led out from the sample gas outlet 4, introduced into the analysis unit 6 through the gas paths b and c, the analysis unit 6 irradiates infrared light, detects transmitted light, Analyze the components of the sample gas.

On the other hand, as the purge gas introduced into the semipermeable membrane dryer 1, a part of the sample gas derived from the sample gas outlet 4 of the semipermeable membrane dryer 1 is used. That is, branch point A
A part of the sample gas divided in (1) is introduced into the semipermeable membrane dryer 1 via the gas path f. This purge gas dehumidifies the sample gas passing through the semipermeable membrane tube 1a of the semipermeable membrane dryer 1 described above, is led out from the purge gas outlet 5, and is led to the confluence B via the gas path g.

FIG. 5 shows another conventional gas analyzer. In FIG. 5, 1 is a semipermeable membrane dryer, 2 is a sample gas inlet, 3 is a purge gas inlet, 4 is a sample gas outlet, 5 is a purge gas outlet, 6 is an analyzer, and a, b, c and d are gas paths. In the case of the gas analyzer of FIG. 5, the sample gas sucked by the suction device (not shown) is introduced from the sample gas inlet 2 of the semipermeable membrane dryer 1 via the gas path a and passes through the semipermeable membrane dryer 1. Although it is sometimes dehumidified by the purge gas, this barge gas uses the sample gas after measurement in the analysis unit 6, is introduced from the purge gas inlet 3 via the gas path c, and is discharged from the purge gas outlet 5 after dehumidification.

Further, as another example, it is known that a sample gas is dehumidified by providing a purge gas supply device provided with a pipe to the semipermeable membrane dryer 1 outside the gas analyzer.

[0008]

The conventional gas analyzer is constructed as described above, but a part of the sample gas discharged from the semipermeable membrane dryer or the sample gas discharged after measurement is used as the purge gas. Since the purge gas may not be sufficiently dried or the flow rate of the purge gas is insufficient, the dehumidification performance will be reduced, so a sample gas containing a large amount of water will be introduced into the analysis section, and measurement errors will occur. While occurring, it also caused a failure of the analyzer.

Further, in the structure in which the purge gas supply device provided with the pipe to the semipermeable membrane dryer is provided outside, it is possible to take in the purge gas with sufficient dehumidification performance, but this causes the size increase and cost increase of the device. It was

The present invention was devised to solve the above-mentioned problems, and a sufficiently dry purge gas can be flowed without increasing the size of the device, which may cause a measurement error and a failure of the analyzer. It is an object of the present invention to provide a gas analyzer that can prevent the above.

[0011]

According to the present invention, a means for dehumidifying a sample gas passing through the semipermeable membrane tube by a dehumidifying gas on the outside of the semipermeable membrane tube, and a red gas for the sample gas dehumidified by the dehumidifying means are provided. In a gas analyzer provided with a means for irradiating external light and a means for detecting infrared light transmitted through the sample gas, a gas in which a part of the sample gas is introduced and a dry gas is introduced outside the detecting means. It is characterized by comprising a purifying means and a means for introducing the dry gas discharged from the outside of the detecting means into the dehumidifying means, and dehumidifying the sample gas passing through the semipermeable membrane tube with this dry gas.

[0012]

A part of the sample gas introduced into the semipermeable membrane tube is introduced into the zero calibration gas purification means. This gas is heated and dried by the heating means provided in the gas purification means,
After removing the error component around the infrared light detecting means (removing and dehumidifying the gas component of the measurement gas target), it is introduced to the outside of the semipermeable membrane.

On the other hand, the sample gas is dehumidified by the dry gas introduced outside the semipermeable membrane when passing through the semipermeable membrane tube. Then, the dehumidified sample gas is irradiated with infrared light, and the transmitted light is detected by the detecting means to analyze the components of the sample gas.

[0014]

EXAMPLE FIG. 1 shows a schematic configuration of a gas analyzer according to the present invention. In FIG. 1, 1 is a semipermeable membrane dryer, 2 is a sample gas inlet, 3 is a purge gas inlet, 4 is a sample gas outlet, 5 is a purge gas outlet, 6 is an analysis unit, 7 is a zero gas purifier, 8 is an infrared heater, and 9 is Measuring cell, 10 is sensor, 11 and 12
Is a valve, a, b, c, d, e, f, g, h, i, j,
k is a gas path, A is a gas branch point, and B and C are gas confluence points. Further, FIG. 2 shows a schematic configuration of the analysis unit, 8 is an infrared heater, 9 is a measurement cell, 9a is a gas inlet of the measurement cell, 9b is a gas outlet, 10 is a sensor, 10a is a case of the sensor, 10b. Is a window provided on the case, 10
c is the gas inlet of the case, 10d is the gas outlet, d, e,
h and i are gas paths.

Next, the operation of the gas analyzer shown in FIG. 1 will be described. When analyzing the sample gas, the valve 10 is opened and the valve 11 is closed. The sample gas sucked by the suction device (not shown) is introduced from the sample gas inlet 2 of the semipermeable membrane dryer 1 via the gas path a. When this sample gas passes through the semipermeable membrane dryer 1, it is dehumidified by the dry purge gas introduced from the purge gas inlet 3 via the gas path j. This semipermeable membrane dryer 1 has the same structure as the conventional device. 3, the sample gas introduced into the semipermeable membrane tube 1a made of a polyimide film is introduced from the purge gas inlet 3 and flows through the outer tube 1b when passing through the semipermeable membrane tube 1a. The purge gas dehumidifies the sample gas through the semipermeable membrane tube 1a. And
The dehumidified sample gas is led out from the sample gas outlet 4, and introduced into the measurement cell 9 of the analysis unit 6 from the gas inlet 9a via the gas paths b, c, d. At this time, the sample gas is irradiated with the infrared light R from the infrared heater 8, and the transmitted infrared light R is detected by the sensor 10 in the case 10a through the window 10b made of calcium fluoride crystal, Analyze the components of the sample gas.

On the other hand, as the purge gas introduced into the semipermeable membrane dryer 1, a part of the sample gas derived from the sample gas outlet 4 of the semipermeable membrane dryer 1 is used. That is, the gas branched at the branch point A is introduced into the zero gas purifier 7 through the gas path f, and when measuring the atmospheric CO concentration, for example, a heater (not shown) provided in the zero gas purifier 7 is used. ) To about 120 ° C. and dry, and all CO in the gas is oxidized through a catalyst to purify CO 2. Then, this dry gas containing no CO is introduced into the case 10a from the gas inlet 10c via the gas path h, and the measurement error component existing around the sensor 10 is removed (of the gas component CO of the measurement gas target). Removal and dehumidification). As a result, the measurement error component contained in the atmosphere around the sensor 10 is removed. Further, the purge gas discharged from the gas outlet 10d merges with the gas discharged from the gas outlet 9b of the measurement cell 9 at a confluence point C, and then passes through the gas path i from the purge gas inlet 3 to the outer tube of the semipermeable membrane dryer 1. 1b, the sample gas passing through the semipermeable membrane tube 1a of the semipermeable membrane dryer 1 described above is dehumidified, and is discharged from the purge gas outlet 5.

Next, the operation of this apparatus at the time of zero calibration will be described. At this time, the valve 10 is closed and the valve 11 is opened. The sample gas derived from the sample gas outlet 4 of the semipermeable membrane dryer 1 has a valve closed, so that the branch point A
All are introduced into the zero gas purifier 7 via the gas paths b and f without being split. Then, a part of the gas obtained by oxidizing all the CO in the sample gas by the zero gas purifier 7 and removing the CO is introduced into the measurement cell 9 as a zero calibration gas through the gas path g and the valves 10 and 11. To be done. At this time, the sensor 10 detects the transmitted light of infrared light (not shown) radiated to the zero gas through the measurement cell 9 to know the amount of infrared transmitted light of the sample gas when CO is not contained in advance. The above-mentioned sample gas is actually measured on the basis of the amount of transmitted light. In addition, a part of the gas purified by the zero gas purifier 7 is
It is used as a purge gas for the sensor 10.

In the above embodiment, the gas paths i, e, j
An air suction device is provided in the middle of any of the above conditions to suck air and mix it with the purge gas derived from the case 10a of the sensor 10, whereby the flow rate of the purge gas can be increased.

Further, in the above embodiment, the polyimide film is used for the semipermeable membrane tube 1a, but it can be dehumidified by using the fluorine resin film.

Further, in the above-mentioned embodiment, the gas discharged from the case 10a of the sensor 10 and the gas discharged from the measuring cell 9 are used as the purge gas by combining them.
It is also possible to use only the gas from the sensor 10 as the purge gas.

[0021]

The apparatus of the present invention is configured as described above, and since a part of the sample gas is heated and dried by the zero gas purifier equipped with the heating means, the purge gas having a high dehumidifying performance is used as the semipermeable membrane dryer. The measurement error can be removed and the failure of the analyzer can be prevented.

Further, an air suction device is provided in the middle of any of the gas paths i, e, and j to suck in air and mix with the purge gas discharged from the case 10a surrounding the sensor 10 so that the structure is simple. The purge gas flow rate can be increased, and the dehumidifying effect of the semipermeable membrane dryer 1 can be enhanced.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a gas analyzer according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of an analysis unit in the present invention.

FIG. 3 is a diagram showing a schematic configuration of a conventional gas analyzer.

FIG. 4 is a diagram showing a semipermeable membrane dryer.

FIG. 5 is a diagram showing a schematic configuration of a modification of a conventional gas analyzer.

Claims (1)

[Claims] 1. A means for dehumidifying a sample gas passing through the semipermeable membrane tube by a dehumidifying gas outside the semipermeable membrane tube, and a means for irradiating the sample gas dehumidified by the dehumidifying means with infrared light. In a gas analyzer provided with a means for detecting infrared light transmitted through the sample gas, a gas purifying means for introducing a dry gas to the outside of the detecting means by introducing a part of the sample gas, and the outside of the detecting means. Means for introducing the dry gas discharged from the dehumidifying means to the dehumidifying means, and dehumidifying the sample gas passing through the semipermeable membrane tube with the dry gas.