JPS61247939A - Sampling device for exhaust gas monitor - Google Patents

Abstract

PURPOSE:To solve the problem of a decrease in ability to adsorb iodine due to acid, and to prevent corrosion securely and measure radiation accurately by using mordenite series silver zeolite as an adsorbent and using triethyl amine which contains ethylene tetrafluororesin as a carrier as the filler of a scrabbler. CONSTITUTION:A cartridge 27 for iodine collection uses mordenite series silver zeolite as the adsorbent. The scrabber 28 uses triethyl amine which contains ethylene tetrafluororesin for HCl removal as the carrier. The mordenite series silver zeolite in the cartridge 27 for iodine collection has almost no decrease in ability to adsorbing-iodine due to acid and adsorbs corrosive gas such as SOx and NOx. The scrabbler 28 adsorbs and removes HCl and sample gas passed through a dust sampler 3 have corrosive gas such as SOx, NOx, and HCl removed completely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a sampling device for a device for monitoring exhaust gas containing radioactivity.

[Technical background of the invention and its problems]

It is mandatory to measure the concentrations of radioactive dust, iodine, and rare gases contained in gaseous substances discharged from nuclear facilities. Gas emitted from miscellaneous solid incinerators in nuclear facilities is no exception, but this exhaust gas contains sulfur oxides (S) generated during combustion.
Ox), nitrogen oxides (NOx) and hydrogen chloride (HC)
Contains corrosive gas (1), so consideration must be given to ensure measurement accuracy and sufficient countermeasures against corrosion are required.

Generally, such measurements are performed by continuous sampling of the sample gas. As a sampling device, it is necessary to pay special attention to the following points.

■ For accurate measurements, it is necessary to avoid condensation due to natural cooling of the sample before measurement or dehumidification due to forced cooling. This is to prevent the dissolution of.

(2) The sample has a high dew point due to the SOx contained therein, and heating to 150 to 200°C is required to prevent dew condensation.

(2) Considering the corrosion resistance of the equipment, it is desirable to remove the corrosive gas in the sample as early as possible in the upper reaches of the sampling equipment, but as mentioned in item 0 above, this must not cause measurement errors.

■ From the viewpoint of economical efficiency and heat resistance of the device, it is desirable to cool the sample immediately after measurement.

An example of a sampling device that takes the above points into consideration is proposed in Japanese Patent Application No. 59-146973.

This example will be explained below with reference to FIG. As shown in Figure 2, the sampling probe inside the incinerator exhaust stack ω
High-temperature heat tracing ■ is applied to the piping section (A) from to the dust sampler ■ and the dust sampler ■. This high-temperature heat trace (2) heats the piping section (A) and the dust sampler (2) to approximately 150 to 200°C. Inside the dust sampler (2), a dust filter (2), an iodine collection cartridge (2), and a scrubber (2) are provided so that gas flows through them in this order. Since the inside of this dust sampler ■ becomes high temperature, a glass fiber filter paper is used as the dust filter 0, and a silver-impregnated inorganic material such as silver zeolite is used as an adsorbent for the iodine collection cartridge ■. It is designed to withstand high temperatures. The scrubber (2) uses vermiculite, which is a silicate mineral, as its filler in order to selectively remove the corrosive gas SOa. In addition, a filler in which triethylamine is attached to the surface of tetrafluoroethylene resin powder is also used to adsorb and remove HCff and N02.

A gas sampler ■ is installed downstream of the dust sampler ■. The piping section (10) between the dust sampler ■ and the gas sampler ■ is provided with low-temperature heat tracing (11) to heat the piping section (10) above the water dew point.
The temperature is maintained at about 50-60°C. These dust sampler ■ and gas sampler ■ are equipped with radiation detectors (12), (13), count rate meter (14),
(15) is provided.

A cooler (16) is connected to the downstream side of the gas sampler 0, and a flow rate adjustment device (17) is connected to the cooler (16).
), a sampling pump (18) is provided.

Further, a drain pot (19) is connected to the cooler (16).

This sampling device uses high-temperature heat tracing (2) to prevent condensation, which causes dust and iodine to be measured to accumulate inside piping and equipment, resulting in measurement errors. moreover.

The feature is that corrosive acidic components are removed by the filling in the scrubber (c), and there is no need to consider the acid dew point of equipment downstream of the scrubber (c).

However, this sampling device still has the following problems.

(,) The silver zeolite filled in the iodine collection cartridge (2) generally has a reduced ability to adsorb iodine due to acid.

[b) As a countermeasure for item 81 above, if the scrubber (■) is placed upstream of the iodine collection cartridge (■), this scrubber (■) itself will absorb as much iodine as it does, so when measuring iodine, , it is necessary to measure both the iodine collection cartridge (2) and the scrubber (2), which makes the work complicated.

(C) The filling inside the scrubber is SOx, NOx,
Since they are not effective against HCII at the same time, it is necessary to combine various fillers in order to remove all of the corrosive gases contained therein.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sampling device for an exhaust gas monitor that eliminates the problem of a decrease in iodine adsorption capacity due to acids and ensures reliable corrosion prevention and radiation measurement accuracy.

[Summary of the invention]

The present invention extracts air from an exhaust gas source and flows it through a dust filter in a dust sampler, an iodine collection cartridge, and a scrubber under high-temperature heat trace conditions, and the sample gas exiting the dust sampler is kept at a low temperature. In a sampling device for exhaust gas monitoring that leads to a gas sampler under heat tracing conditions, a mordenite-based zeolite is used as an adsorbent in the iodine collection cartridge, and a tetrafluoroethylene resin is used as a carrier as a filler in the scrubber. This is a sampling device for exhaust gas monitoring that uses triethylamine.
The mordenite-based zeolite in the iodine collection cartridge has almost no decrease in iodine adsorption ability due to acid, and also adsorbs corrosive gases such as SOx and NOx. Therefore, by using such an iodine collection cartridge, more accurate iodine measurement is possible.

In addition, since only the removal of HCa needs to be considered downstream of the iodine collection cartridge, only triethylamine with tetrafluoroethylene resin as a carrier can be used as the scrubber filling, reducing the pressure loss of the entire sampling system. can do.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sampling device for exhaust gas monitoring according to an embodiment of the present invention. In the six figures, ■ indicates the incinerator exhaust stack, ■ indicates the sampling probe, ■ indicates the dust sampler, (A) indicates the piping section, and
is high temperature heat trace, (0 is dust filter, (27
) is an iodine collection cartridge.

(28) is a scrubber, ■ is a gas sampler, (10) is a piping section, (11) is a low-temperature heat trace, (12) and (13) are a radiation detector, (14) and (15)
is a counting rate meter, (16) is a cooler, (17) is a flow rate adjustment device, (18) is a sampling pump, and (19) is a drain pot. Since each element other than the iodine collection cartridge (27) and the scrubber (28) is the same as that in FIG. 2, detailed explanation will be omitted.

Mordenite-based zeolite is used as an adsorbent in the iodine collection cartridge (27).

Further, the scrubber (28) is filled with triethylamine using tetrafluoroethylene resin as a carrier for HCl2 removal.

The operation of the sampling device for exhaust gas monitoring according to an embodiment of the present invention constructed as described above will be described below, focusing on the iodine collection cartridge (27) and the scrubber (28), which are different from the conventional example.

The sample gas that has passed through the piping section (which has been subjected to high-temperature heat tracing ()) is introduced into the dust sampler (■) without condensation even at a high dew point. After the sample gas has dust collected by the dust filter 0 in the dust sampler (2), it passes through the iodine collection cartridge (27). The mordenite-based zeolite in the iodine collection cartridge (27) has almost no decrease in iodine adsorption ability due to acid.
In addition, SOx.

It also adsorbs corrosive gases such as NOx. A scrubber (28) filled with triethylamine using tetrafluoroethylene resin as a carrier is installed downstream of the iodine collection cartridge (27), so that HC (1) is adsorbed and removed. The sample gas that passed through the dust sampler ■ is SOx
, NOx, and HCa are all removed.

Therefore, dew condensation of the sample gas flowing downstream from the dust sampler (1) can be prevented simply by subjecting it to low-temperature heat tracing (11) above the water dew point (approximately 50 to 60°C). Then, the sample gas exiting the gas sampler (1) is cooled and dehumidified by the cooler (16), and subsequent heat tracing is unnecessary. Furthermore, by lowering the temperature of the sample gas, the life of the sampling pump (18) can be extended.

In the sampling device for exhaust gas monitoring according to one embodiment of the present invention, mordenite-based zeolite is used as the adsorbent in the iodine collection cartridge (27), thereby solving the problem of decrease in iodine adsorption capacity due to acid. At the same time, it has become possible to adsorb and remove SOx and NOx at the same time. As a result, more accurate iodine measurement becomes possible. Then, install the iodine collection cartridge (2
7), only the removal of HCffi needs to be considered, so the scrubber (28) only needs to be filled with triethylamine using tetrafluoroethylene resin as a carrier, which reduces the pressure loss of the entire sampling system. can.

Note that the present invention is not limited to the embodiment shown in FIG. 1. For example, the present invention is not limited to the embodiment shown in FIG. By using a mixture with triethylamine, it is possible to eliminate the scrubber and further simplify the equipment.

〔Effect of the invention〕

As detailed above, according to the present invention, in a sampling device for exhaust gas monitoring, mordenite-based zeolite is used as the adsorbent in the iodine collection cartridge, thereby solving the problem of decrease in iodine adsorption ability due to acid. In addition, it becomes possible to adsorb and remove SOx and NOx at the same time, and as a result, more accurate iodine measurement becomes possible. Furthermore, since it is only necessary to remove HCl1 downstream of the iodine collection cartridge, there is the problem that in the past, it was necessary to remove all SOx, NOx, and HCl2, which required the use of a combination of various fillers in the scrubber. resolved. Therefore, triethylamine with tetrafluoroethylene resin as a carrier for removing HCl2 is sufficient as the filler for the scrubber, which reduces the pressure loss of the entire sampling system and prevents the equipment from becoming larger. effective.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a sampling device for exhaust gas monitoring according to an embodiment of the present invention, and FIG. 2 is a system diagram of a conventional example of a sampling device for exhaust gas monitoring. 1... Incinerator exhaust stack 3... Dust sampler 5... High temperature heat trace 6... Dust filter 9... Gas sampler 11... Low temperature heat trace 18... Sampling pump 27... Iodine collection cartridge 28... Scrubber agent Patent attorney Inoue - Male I4 Store No. 1 Figure 2

Claims (1)

[Claims] Air is extracted from the exhaust gas source and flows from the dust filter in the dust sampler to the scrubber under high-temperature heat tracing conditions, via the iodine collection cartridge, and the sample gas exiting the dust sampler is passed under low-temperature heat tracing conditions. In a sampling device for exhaust gas monitoring that leads to a gas sampler, mordenite silver zeolite is used as an adsorbent in the iodine collection cartridge, and triethylamine with tetrafluoroethylene resin as a carrier is used as a filler in the scrubber. A sampling device for exhaust gas monitoring.