JP3615939B2 - Metal sodium treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metallic sodium treatment apparatus for converting metallic sodium into a stable material that is easy to discard.
[0002]
[Prior art]
FIG. 2 shows a system diagram of a conventional metal sodium treatment apparatus.
[0003]
Reference numeral 1 in the figure indicates a sodium container containing metallic sodium 2. A nitrogen supply line 3 is connected to the sodium container 1. The sodium container 1 is connected to a reaction container 6 for containing a sodium hydroxide aqueous solution 5 through a metal sodium supply pipe 4. A hydrogen exhaust line 7 is connected to the reaction vessel 6. The reaction vessel 6 is connected to a line 9 having a circulation pump 8 for circulating the sodium hydroxide aqueous solution 5. A supply water line 10 for supplying pure water is connected to the line 9. The reason for replenishing the pure water is that the aqueous solution of sodium hydroxide becomes a high concentration as the reaction proceeds, so that it is maintained at an appropriate concentration by replenishing the pure water. A heat exchanger 11 for removing heat generated by the reaction is interposed in the line 9 between the circulation pump 8 and the reaction vessel 6. The heat exchanger 11 is provided with a cooling water supply line 12 for cooling the heat exchanger 11.
[0004]
The operation of the metal sodium treatment apparatus having such a configuration is as follows. First, the metal sodium 2 in the sodium container 1 is supplied from the nitrogen supply line 3 to the reaction container 6 through the metal sodium supply pipe 4 by nitrogen pressurization. The metallic sodium that has entered the reaction vessel 6 reacts with the aqueous sodium hydroxide solution 5 in the reaction vessel 6 to become sodium hydroxide and hydrogen. The generated hydrogen is circulated by the circulation pump 8 through the hydrogen exhaust line 7, and the heat generated by the reaction is removed by the heat exchanger 11. Here, the heat exchanger 11 is cooled by the cooling water supply line 12. Moreover, since the sodium hydroxide aqueous solution 5 becomes a high concentration as the reaction proceeds, pure water is supplied from the makeup water line 10 and is maintained at an appropriate concentration.
[0005]
The reaction is controlled by controlling the supply of nitrogen gas to the sodium container and maintaining the amount of metal sodium supplied to the reaction container at an appropriate amount. As a prior art, there is a method of treating an alkali metal waste using carbon dioxide gas and wet gas (Patent Registration No. 1970961, JP-B-6-40155), each of which is a treatment by individual reaction, and a large amount of metallic sodium Not suitable for processing.
[0006]
By the way, in the case of treatment using only carbon dioxide gas, only sodium hydroxide becomes sodium carbonate, and metal sodium and carbon dioxide gas do not react at a normal treatment temperature, so that treatment of metal sodium cannot be performed. In wet gas treatment, metallic sodium can be converted to sodium hydroxide, but a large amount of hydrogen gas is released. Therefore, it is necessary to devise a method for treating this hydrogen gas, and the treatment substance is treated as waste. There is a problem that arises.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a metal sodium treatment apparatus capable of treating a large amount of metal sodium without releasing a large amount of hydrogen gas as in the prior art.
[0009]
[Means for Solving the Problems]
Metallic sodium is a substance that reacts with water to generate hydrogen and has the risk of ignition and explosion. This metallic sodium is used as a coolant for fast breeder reactors, and a safe disposal method for metallic sodium that is no longer needed is being studied. As a method of treating this metallic sodium, it is common to convert it to a compound such as sodium hydroxide or sodium alcoholate, and then to form a safer compound such as sodium carbonate or sodium chloride.
[0010]
In the present invention, the following reaction is caused by blowing carbon dioxide gas containing moisture onto metallic sodium, and the metal sodium is directly converted into sodium carbonate.
[0011]
2Na + H ₂ O + CO ₂ → Na ₂ CO ₃ + H ₂
The sodium carbonate produced at this time is separated as a solid, carbon dioxide and oxygen are supplied to the circulating hydrogen-containing gas, oxygen and hydrogen are converted into moisture by a recombination catalyst, and then supplied again to the reaction vessel.
[0012]
The reaction of metallic sodium is an exothermic reaction, but the reaction heat is almost divided into two parts: the heat generated by the reaction between metallic sodium, carbon dioxide and moisture, and the reaction heat from the recombination catalyst. Is easy. The reaction can be controlled by controlling the flow rate of the mixed gas of carbon dioxide and oxygen supplied. In particular, the sodium metal used in the nuclear reactor contains radioactive materials, so care must be taken in the overall waste materials.
[0013]
However, in the case of the present invention, it is only necessary to supply the carbon dioxide gas and oxygen used in the reaction. Hydrogen is generated in the reaction process, but since this is used for recirculation, the exhaust of hydrogen as in the conventional method does not occur.
[0015]
The present invention includes a reaction vessel in which metallic sodium is accommodated, a product collection tank that collects sodium carbonate generated by the reaction of carbon dioxide containing moisture and the metallic sodium, and a filter that removes dust from the sodium carbonate. A recirculation blower, a recombiner containing a catalyst that converts oxygen and hydrogen into moisture, and a feed gas heat removal device, the reactor, the product recovery tank, the filter, the circulation blower, The recombiner and the supply gas heat remover constitute a circulation gas system in this order, and a mixed gas supply line for supplying a mixed gas of carbon dioxide and oxygen consumed by the reaction is connected to the circulation blower and the recycler. The metal sodium treatment apparatus is connected to a circulation line between the couplers .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIG.
[0017]
Reference numeral 21 in the figure is a reaction vessel containing metallic sodium 22. A supply gas heat remover 24 is connected to the reaction vessel 21 via a reaction gas supply line 23 of carbon dioxide containing moisture. A waste tank (product recovery tank) 27 for storing sodium carbonate 26 is connected to the reaction vessel 21 through a suction pipe 25. The supply gas heat remover 24 and the waste tank 27 are connected by a recombiner 29 containing a catalyst 28, a circulation blower 30, a filter 31, and a circulation line 33 including a heat exchanger 32. A cooling water supply line 34 is connected to the supply gas heat remover 24 and the heat exchanger 32. A mixed gas supply line 35 is connected to a circulation line 33 between the recombiner 29 and the circulation blower 30.
[0018]
The operation of the metal sodium treatment apparatus having such a configuration is as follows. Carbon dioxide gas containing moisture is sent from the reaction gas supply line 23 to the reaction vessel 21 where metal sodium and carbon dioxide gas react. The sodium carbonate produced in the reaction vessel 21 is stored in the waste tank 27 through the suction pipe 25. The heat of reaction is removed by a heat exchanger 32, and sodium carbonate dust is removed by a filter 31 and circulated by a circulation blower 30. Further, the mixed gas of carbon dioxide and oxygen consumed by the reaction is supplied to the circulating gas system by the mixed gas supply line 35. This gas passes through the recombiner 29 containing the catalyst 28 and the supply gas heat remover 24 in order, and is supplied again as a reaction gas.
[0019]
As described above, the metal sodium treatment apparatus according to the above embodiment is a waste that collects the reaction container 21 in which the metal sodium 22 is accommodated and the sodium carbonate 26 generated by the reaction between the carbon dioxide gas containing water and the metal sodium 22. A recovery tank 27, a heat exchanger 32 that removes reaction heat, a filter 31 that removes the duct of sodium carbonate 26, a circulation blower 30 that circulates through the duct of sodium carbonate 26, and converts oxygen and hydrogen into moisture. A recombiner 29 containing the catalyst 28 and a supply gas heat remover 24 are provided. The reaction vessel 21, the waste recovery tank 27, the heat exchanger 32, the filter 31, the circulation blower 30, the recombiner 29 and the supply The gas heat remover 24 constitutes a circulating gas system and includes a mixed gas supply line 35 for supplying a mixed gas of carbon dioxide and oxygen consumed by the reaction. And it has a formation. In such a metallic sodium treatment apparatus, the metallic sodium 22 in the reaction vessel 21 is blown onto the metallic sodium 22 through the reactive gas supply line 23 and treated with carbon dioxide containing moisture from the feed gas heat remover 24 to directly treat the sodium carbonate 26. Thus, a large amount of metallic sodium 22 can be processed without releasing a large amount of hydrogen gas as in the prior art. In the above embodiment, hydrogen is generated in the reaction process. However, since this is recirculated, hydrogen is not exhausted as in the conventional method.
[0021]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a metal sodium treatment apparatus capable of treating a large amount of metal sodium without releasing a large amount of hydrogen gas as in the prior art .
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a metal sodium treatment apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a conventional metal sodium treatment apparatus.
[Explanation of symbols]
21 ... reaction vessel,
22 ... Metal sodium,
23 ... Reaction gas supply line,
24 ... Supply gas heat remover,
25 ... suction tube,
26 ... Sodium carbonate,
27 ... Waste tank,
28 ... Catalyst,
29 ... Recombiner,
30 ... circulation blower,
31 ... filter,
32 ... heat exchanger,
33 ... circulation line,
34 ... Supply gas heat remover,
35 ... Mixed gas supply line.

Claims (1)

A reaction vessel containing sodium metal, a product recovery tank for recovering sodium carbonate produced by the reaction of carbon dioxide containing water and the metal sodium, a filter for removing the sodium carbonate dust, and a circulation blower; A recombiner containing a catalyst that converts oxygen and hydrogen into moisture and a feed gas heat remover;
The reactor, the product recovery tank, the filter, the circulation blower, the recombiner, and the feed gas heat removal device constitute a circulation gas system in this order, and carbon dioxide and oxygen consumed by the reaction. A metallic sodium treatment apparatus, wherein a mixed gas supply line for supplying a mixed gas is connected to a circulation line between the circulation blower and the recombiner .

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