JPS6331756B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for treating iodine-containing exhaust gas, and more particularly to an apparatus for purifying exhaust gas containing radioactive iodine.

Radioactive iodine has sublimation properties and is emitted along with exhaust gas from air-cooled nuclear reactors, nuclear fuel reprocessing plants, nuclear fuel molding plants, and fume hoods in laboratories that handle radioactive materials. This radioactive iodine (I ¹³¹ )
Although it has a relatively short lifespan, it has been confirmed that it descends from the troposphere and contaminates pastures, etc., and is concentrated in the human thyroid gland through milk from dairy cows that eat this pasture. Facilities that handle materials are required to treat exhaust gas to remove radioactive iodine.

The most widely used exhaust gas treatment equipment for this purpose has the structure shown in Figure 1 (schematic side view), in which an exhaust gas inlet pipe is installed on the side wall of an adsorption tower 1 filled with iodine adsorbent A. 2 and an exhaust gas discharge pipe 3 are provided, and the exhaust gas is sent to the adsorption tower 1.
Radioactive iodine is removed (hereinafter referred to as decontamination) by passing it through the air. In the figure, an exhaust gas pipe 4 communicating with exhaust gas generation equipment and a decontamination gas pipe 5 communicating with a chimney or the like are connected to an exhaust gas introduction pipe 2 and an exhaust gas discharge pipe 3 via flanges 6 and 7, respectively. In this case, the flanges 6 and 7 have a fitted structure, for example, as shown in FIG. 2 (a sectional view of the main part), to prevent leakage of contaminated gas. Because of this connection structure, when replacing and moving the adsorption tower 1, it was necessary to move the adsorption tower 1 in two directions, horizontally and vertically, making the replacement operation complicated. Moreover, since there are two pipe connections, for example, the mounting positions of the flanges 6 and 7, which are slightly exaggerated in Fig. 3, may be shifted in the height or lateral direction, or may be tilted relative to each other. If this occurs, the airtightness of the connection may be compromised, resulting in the problem of leakage of contaminated gas.

The present invention has focused on the above-mentioned circumstances, and has developed a system that facilitates attachment and detachment of the adsorption tower, reliably prevents leakage of contaminated gas from the connection, and further improves the decontamination efficiency of exhaust gas. We have been conducting intensive research in hopes of developing a device. The present invention was completed as a result of such research, and consists of a fixed double tubular header and an upper part of the header,
This is an iodine-containing exhaust gas treatment device consisting of a double tubular processing container having a skirt portion, and the header and the processing container are detachably attached so that the inner tubes communicate with each other and the outer tubes communicate with each other. consists of one of the outer tube and the inner tube being a process gas inlet tube and the other being a treated gas discharge tube, and a skirt mounting seat is integrally provided so as to surround the header outer tube. Correspondingly, one of the outer pipe and the inner pipe is used as an outgoing path for the treated gas, and an iodine adsorption layer is arranged in the outgoing path, and the other is used as a return path for the treated gas, and the outgoing and returning paths are passed through a filter for removing suspended contaminants. to communicate,
The gist is that the lower end of the skirt is configured to be detachably attached to the mounting seat and to be attached airtightly.

The structure and effects of the present invention will be explained below based on the drawings showing the embodiments. However, the following are representative examples and do not limit the present invention, and only within the scope that can comply with the spirit of the above and below. All changes to the design are within the scope of the present technology.

FIG. 4 is a schematic longitudinal cross-sectional view illustrating the exhaust gas treatment device of the present invention, and FIGS. 5 and 6 are -
In the line and -line cross-sectional equivalent views, this device is shown on the pedestal 8.
A header 9 fixed to the header 9, and a portable absorption container 1 detachably attached to the header 9.
0. The header 9 is formed into a double tube shape, and in the illustrated example, the outer tube 9a functions as a processing gas introduction tube, the inner tube 9b functions as a treated gas discharge tube, and the outer tube 9a functions as a treated gas discharge tube. A skirt mounting seat (hereinafter simply referred to as mounting seat) 11 configured in the form of a flange is integrally provided around the periphery, and the entire header 9 is fixed to the base 8 by a frame 12 that is welded and fixed to the mounting seat 11.

On the other hand, the processing container 10 is also configured in a double tube shape corresponding to the header 9, and the upper end of the outer tube 10a is connected to the lid 1.
3, and the lower part integrally connects its inner circumferential wall and the lower end outer circumferential wall of the inner tube 10b with a disk-shaped sealing plate 14, and the lower end of the outer tube 10a extends downward. A skirt portion 15 is formed, and a flange portion 16 is formed at the lowermost end of the skirt portion 15 so as to face a mounting seat 11 provided on the header 9. Furthermore, a large number of processing gas introduction holes 17 are provided on the outer circumferential side of the inner tube joint portion of the disk-shaped sealing plate 14 so as to face the opening 18 provided at the upper end of the outer tube 9a of the header 9, and the lower end of the inner tube 10b is Header 9
facing the upper end opening of the inner tube 9b. Therefore, in the processing container 10, as shown by the arrow in FIG. 4, the space between the outer tube 10a and the inner tube 10b constitutes the processing gas outward path, and the inner tube 10b serves as the processing gas return path, and the upper end opening of the inner tube 10b constitutes the processing gas return path. constitutes a processing gas turning section. On the above-mentioned outward journey, the return layer (two layers in the figure) of iodine adsorption layers (silver zeolite, etc.) 19a, 1
9b are arranged at appropriate intervals, and a floating contaminant removal filter 20 (glass wool, aluminum foil, etc.) is arranged at the processing gas turning section. In the figure, 21 indicates an iodine adsorbent filling port, and 22 indicates a baffle plate for processing gas diffusion provided as necessary. The downward protruding length of the skirt portion 15 in the processing container 10 and the upward protruding length of the inner and outer tubes in the header 9 are made equal, and by fastening the mounting seat 11 and the flange portion 16 with bolts and nuts, the header 9 upper end opening and processing container 1
The lower end opening of 0 is also configured to closely communicate with each other.
23a, 23b, and 23c indicate sealing gaskets.

When treating iodine-containing exhaust gas using such a device, the processing container 10 is assembled and fixed on the header 9 as described above, and the outer pipe of the container 10 is inserted through the inlet 17 from the outer pipe 9a of the header 9. Exhaust gas is supplied into 10a. And the exhaust gas is absorbed by the adsorption layer 19
In the process of rising through a and 19b, iodine is adsorbed and decontamination is performed. In addition to iodine, fine powder radioactive substances are mixed in the exhaust gas, and although some of these are removed by the adsorption layers 19a and 19b, they are completely removed by the floating impurity removal filter placed in the folded part. After being completely purified, the inner tube 1
It is discharged via 0b and 9b.

In such a device, since the exhaust gas introduction/exhaust ports for the adsorption container 10 are provided at one location, preferably concentrically, the relative positions of the introduction/exhaust ports in the communication portion with the header 9 can be adjusted. There is no risk of misalignment, and the airtightness of the communication portion can be improved. Moreover, even if a gas leak were to occur in the communication section, in the present invention, the mounting seat 11 and the flange section 16 are sealed in a double manner by airtight fastening, so that no contamination would be caused outside the processing equipment. Gas leak accidents are completely prevented. Also, the adsorption container 10
When the decontamination effect of the container 1 is saturated and it is time to replace the container 1, the mounting seat 11 and the flange portion 16 are unfastened and the container 1 is replaced.
0 upward and replace it with a new adsorption container 10, and the attachment/detachment work is also easy. The skirt portion 15 also functions as a damage prevention portion during the conveyance process. That is, if an unexpected accident occurs during the conveyance process and the container 10 falls downward, the container will be damaged and the adsorption layer that has absorbed radioactive iodine will be scattered into the working atmosphere, potentially causing a serious accident. serves as a buffering member in the event of a fall, and only the skirt portion 15 is damaged.
Accidents of scattering of pollutants can be prevented.

Furthermore, as explained earlier, the iodine adsorption layers 19a and 19b
If they are arranged in two layers and an appropriate gap is provided in the laminated part, this gap becomes a retention area for the processing gas, where it is redispersed, eliminating channeling when passing through the adsorption layer 19a. The contact efficiency with the processing gas increases and the decontamination effect can be enhanced. For the same purpose, if the adsorption layers are arranged in three or more stages, the decontamination effect can be further enhanced.

Although the present invention is configured as described above, for example, various design changes other than the illustrated example are possible in terms of specific design. For example, although a double cylindrical adsorption container is shown, it may be a rectangular cylindrical one. Furthermore, although an example is shown in which the outer tube 9a of the header and the outer tube 10a of the processing container are communicated with each other through a large number of introduction holes 17, they can also be communicated with each other through an annular introduction port. The inner tube 10b may be fixed with a spacer or the like provided at an appropriate position. Furthermore, it is also effective to make the adsorption layers 19a, 19b and the filter 20 of a cassette type so that they can be easily attached and detached, and all such changes are within the scope of the present invention.

The present invention is roughly constructed as described above, and its effects can be summarized as follows.

Since the processing gas inlet and outlet ports of the processing container are provided concentrically at one location, there is no risk of misalignment between the two, and high airtightness can be achieved.

In addition, the processing container and header are airtightly connected not only at the above-mentioned airtight connection but also at the skirt section and mounting seat, creating a double seal structure, completely preventing leakage of contaminated exhaust gas. .

Since the iodine adsorption layer is composed of two or more double layers and gaps are provided between the layers, the processing gas can be spread throughout the adsorption layer, increasing the adsorption efficiency. Moreover, since fine powder radioactive contaminants are removed by the floating matter removal filter, a high decontamination effect can be obtained.

The skirt portion formed below the processing container also functions as a shock absorbing member when the processing container falls, and even if the processing container falls due to an unexpected accident during transportation, damage to the container body is prevented.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view showing a known processing device, Fig. 2 is a partially cutaway side view showing the connection structure of the processing gas introduction/discharge section, and Fig. 3 shows the connection status of the processing gas introduction/discharge section. The explanatory drawings, FIGS. 4 to 6, illustrate the processing apparatus of the present invention, in which FIG. 4 is a schematic vertical cross-sectional view, and FIGS. 5 and 6 are cross-sectional views taken along lines - and - in FIG. 4. 9... Header, 10... Processing container, 9a, 1
0a...outer pipe, 9b, 10b...inner pipe, 11...
Mounting seat, 15...skirt part, 16...flange part, 17...processing gas introduction hole, 19a, 19b
...Adsorption layer, 20...Floating matter removal filter.

Claims (1)

[Scope of Claims] 1. An iodine-containing exhaust gas treatment device comprising a fixed double-tubular header and a double-tubular processing vessel disposed above the header and having a skirt portion, wherein the header and the processing vessel are is removably attached so that the inner tubes and the outer tubes communicate with each other, and the header has one of the outer tube and the inner tube as a treated gas introduction tube, and the other as a treated gas discharge tube, A skirt mounting seat is integrally provided so as to surround the header outer tube, and on the other hand, in the processing container, one of the outer tube or the inner tube corresponding to the header is used as a processing gas outgoing path, and an iodine adsorption layer is arranged in the outgoing path. At the same time, the other side is used as a return route for the treated gas, the outward route and the return route are communicated via a floating contaminant removal filter, and the lower end of the skirt is configured to be detachably attached to the mounting seat in an airtight manner. A treatment device for iodine-containing exhaust gas characterized by: 2. The processing apparatus according to claim 1, wherein the iodine adsorption layer is formed in at least two stages. 3. The processing apparatus according to claim 1 or 2, wherein the filter material is glass wool or aluminum foil. 4. The apparatus according to any one of claims 1 to 3, wherein the outer header pipe is a processing gas outward path, and the inner pipe is a processed gas return path. 5. The apparatus according to any one of claims 1 to 4, wherein the double tubular processing container is portable. 6. The device according to any one of claims 1 to 5, wherein the floating contaminant removal filter is provided at the folded portion between the outgoing and returning gas paths in the processing container.