JPS6020051B2 - Harmful substance separation device in exhaust gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In facilities capable of generating radioactive fission products, a furnace filtration device for exhaust gas is provided for the purpose of protecting the environment.

In particular, radioactive iodine (decomposed iodine) needs to be reliably separated even in the event of an accident after long-term operation of such a filtration device. e.g. radioactive iodine and/or
To remove gaseous contaminants such as hydrocarbons, a furnace tank filled with activated carbon is typically used.

In order to remove suspended solids from the exhaust gas, so-called suspended solids filters are connected before and after the filter. The object of the present invention is to provide a filtration device which has an activated carbon filtration device and which ensures a sufficient filtration efficiency, especially for decomposed iodine, even after long-term operation, and which makes it possible to achieve maximum utilization of the activated carbon material. It is about providing.

The invention therefore provides an exhaust gas system capable of producing iodine isotopes (decomposed iodine) having at least one activated carbon furnace inserted in the exhaust gas line and connected in series after the suspended solids furnace. This invention relates to a device that separates harmful substances from gas.

According to the invention, this object is achieved by further connecting at least one activated carbon furnace upstream of the suspended solids furnace, and connecting said suspended solids furnace with an activated carbon furnace connected in series in front of said suspended solids furnace. This is achieved by connecting a measuring device operated by gaseous pollutants of the air into the connecting conduit between them.

Next, the present invention will be described in more detail with reference to drawings showing embodiments of the present invention.

From a building 1 of a nuclear power plant or any other building capable of producing fissile material, for example four or more are connected in parallel to each other via a moisture separator 3 and a subheater 4. An exhaust conduit 2 is passed toward the air introduction conduit 5 of the activated carbon filter 6 .

The air outflow conduit 7 closes into a connecting conduit 8, from which an inflow conduit 9 for the suspended solids reactor branches off. The air purified of suspended solids in the suspended solids filter 10 is entrained by the conduit 11, the air inlet conduit 12 of the activated carbon filter 13, and from there the air outlet conduit 14 and, if necessary, air. It reaches the exhaust chimney 18 via a subsequent furnace 15 for removing activated carbon particles and also via an exhaust line 16 and a parallel-connected fan 17 . The activated carbon filters 6, 13, which are connected one after the other, are continuously flowed with the air to be filtered. During the operation of nuclear power plant reactors, fission products are generated during and after an accident. In this case, only the radioactivity of decomposed iodine is the main problem. Further hydrocarbons may be present in the air in the form of gases, which may occur, for example, due to evaporation from paint applications or similar measures in nuclear power plant buildings. In the device of the present invention, such harmful substances that generally cause a load on the reactor are removed from the nuclear power plant building through the exhaust pipe 2.
It reaches the activated carbon filter 6, possibly together with suspended solids contained in the air, where the gaseous hydrocarbons are largely absorbed. A measuring device 19 for measuring hydrocarbons in the air is connected to the connecting conduit 8. This measuring device 19 directly or indirectly via an operating line 20 controls a valve bank 21 which causes a portion of the activated carbon in the activated carbon filter 6 to be exchanged. Each valve of the valve group 21 is inserted into an activated carbon outflow conduit 22 which leads via a feed device 23 to an activated carbon reservoir 24 . In order to likewise withdraw the activated carbon from the activated carbon filter 13, a valve bank 25, an activated carbon outflow conduit 26 and a feed device 27 for the activated carbon tank 28 are provided. Therefore, activated carbon can be replaced without the need for workers to directly touch it.
Therefore, there is no risk of contamination.

The air from which the gaseous hydrocarbons normally generated in the activated carbon filtration device 6 have been removed reaches the suspended solids filtration device 1, where, in addition to the expected suspended solids, the mist that may appear in the event of an accident is removed. Decomposed iodine is collected. Further, from here, air from which suspended solids have been removed flows out to the exhaust chimney 18 via the activated carbon filter 13 and the subsequent filter 15. In the device according to the invention, only preconditioned air is supplied to the activated carbon filter 13.

Taking into account that the loading of the activated carbon in the activated carbon furnace 13 due to the adsorption of decomposed iodine, elemental iodine and other possible harmful substances will gradually reduce the separation efficiency, a constant minimum efficiency can be maintained even over a relatively long period of operation. It is controlled so that it does not go under. Activated carbon is withdrawn from the activated carbon furnace 6 only if the meter 19 indicates that the connecting conduit 8 contains an unacceptable concentration of hydrocarbons.

This measure maximizes the utilization of the activated carbon loaded with harmful substances in the activated carbon filters 6 and 13. There is therefore no need to replace the activated carbon before its permissible consumption is reached, taking into account possible accidents. The utilization of the activated carbon in the activated carbon filters 6 and 13 will be further increased if one activated carbon filter is constructed in accordance with FIGS. 2-4.

The activated carbon furnaces 6 and 13 are provided with a funnel-shaped lower part 29 bounded from the center by the support grid 30'. The support grid 30 has a bridge piece 31 surrounding a square closure 32. Experiments have shown that such a support grid 30
When withdrawing the activated carbon from the activated carbon filters 6 and 13, the activated carbon stored inside the activated carbon filters 6 and 13 acts to slide down sufficiently evenly from top to bottom (without creating a funnel shape in the activated carbon bed). When only a portion of the stored activated carbon is withdrawn from the activated carbon filters 6 and 13 in each case, only the activated carbon that has been present in the filter the longest is removed. The air outflow conduits 7, 14 are arranged on the sides of the activated carbon furnaces 6, 13, so that there is still some stored activated carbon between the filling connection pipe 33 and the plane of the air outflow conduits 7, 14. They are disposed opposite to the upper filling connecting pipe 33 with an interval as permissible.

In order to extract the air at the level of the air outflow conduits 7, 14 from the cellar and to distribute it evenly within the cell at the level of the air outflow conduits 5, 12, a distribution having upper and lower vertices in this plane is required. Conduits 34, 35 are arranged. If the measuring device 19 indicates an unacceptable value for the hydrocarbon content of the air, the activated carbon furnace 6 will discharge, at most, above the air distribution conduit 34 in the plane of the air outlet conduit 7. The amount of activated carbon present is drawn off.

This ensures that the effective stack height of the activated carbon is always the same even during the withdrawal of the activated carbon. The same applies to the carbon extraction in the activated carbon furnace 13. In this case, a rear-connected measuring device (iodine monitor) in the exhaust chimney 18 indicates an unacceptable concentration of iodine in the air. Since the air and the activated carbon move on a countercurrent principle, the maximum loading of the activated carbon occurs before it is discharged from the activated carbon filter via the valve. In the apparatus of the present invention, activated carbon furnace 1
3 mainly has to treat only the decomposed iodine products from the air, so activated carbon is used in the activated carbon filter 6, which is especially suitable for the hydrocarbons adsorbed from the exhaust gas. On the other hand, for this activated carbon filter 13, solbenes (Solbens), which is particularly suitable for separating iodine, is used.
Particular preference is given to using carbon fibers (activated carbon materials).

[Brief Description of the Drawings] Figure 1 is a system diagram of the separation device of the present invention, Figures 2 to 4
The figures are a side view, top sectional view and side sectional view of a preferred embodiment of an activated carbon filter, and FIG. 5 is an enlarged plan view of a support grid used in this filter. 1...Nuclear power plant building, 2...Exhaust pipe, 3
... Moisture separator, 4 ... Subheater, 5 ...
...Air inflow conduit, 6...Activated carbon furnace filter,
7...Air 0 outflow conduit, 8...Connecting conduit, 9...Inflow conduit, 10...Suspended solids filter, 11... ...conduit, 12...
Air inflow conduit, 13...Activated carbon furnace, 14
... Air outflow conduit, 15 ... Subsequent furnace filter, 16 ... Exhaust pipe, 17 ... Ventilator, 18 ... Exhaust chimney, 19... Measuring instrument, 21, 25... Valve group, 22, 26...
...Activated carbon outflow conduit, 27, 23... Feeding device, 24, 28... Activated carbon tank, 30... Support grid. Fig. l Fig. 2 Fi9, 3 Fi9・muFig. 5

Claims (1)

Claims: 1. Apparatus for separating gaseous hydrocarbons and radioactive iodine isotopes from the exhaust gas of an installation using at least one activated carbon filter 13 inserted into the exhaust conduit following the suspended solids filter 10. In addition, at least one activated carbon filter 6 is connected in front of the suspended solids filter 10, and this filter 10
A measuring device 19 is connected to the connecting conduit 8 between the activated carbon filter 6 and the activated carbon filter 6 connected in series in front of the activated carbon filter 6, and the measuring device 19 causes the activated carbon in the activated carbon filter 6 to be replaced in response to hydrocarbons in the air. A device for separating harmful substances in exhaust gas. 2. Claim 1, characterized in that the activated carbon filter 13 connected in series behind the suspended solids filter 10 is filled with activated carbon on which a potassium iodide layer is deposited in order to enhance the iodine separation effect. Apparatus described in section. 3. The activated carbon filter 6, 13 is equipped with a charging connection pipe 33 for activated carbon in the upper part of its casing, and below it, air outflow conduits 7, 14 and air inlet conduits 5, 1 are provided at intervals.
2. Device according to claim 1, characterized in that it comprises openings for activated carbon outflow conduits (22, 26). 4. The activated carbon filter 6, 13 is provided with a funnel-shaped lower part 29, and the upper end of the funnel-shaped lower part 29 is provided with a rigid support grid 30 with an opening. equipment. 5. Device according to claim 4, characterized in that the openings of the support grid 30 have a square cross section. 6. Device according to claim 1, characterized in that in the plane of the air outflow conduit 7 there is provided a distribution conduit 34 installed horizontally.