CN212188601U - 14C isotope's separation and purification system - Google Patents

Abstract

The utility model belongs to the technical field of 14C isotope separation purification, concretely relates to separation and purification system of 14C isotope. It comprises a gas oxidation system, a primary low-temperature cooling system, a secondary low-temperature cooling system and 14C-CO which are connected in sequence₂A separation and enrichment system, said 14C-CO₂The separation and enrichment system comprises an exchange tower, a desorption tower and an absorption tower; the outlet of the secondary low-temperature cooling system is connected with the air inlet of the exchange tower body, and the outlet of the exchange tower bottom is connected with the analysis towerThe gas inlet of the tower body is connected, and the gas outlet at the bottom of the desorption tower is connected with the gas inlet at the bottom of the absorption tower. The utility model provides a retrieve 14C's separation and purification system in follow nuclear power station discarded object, this system simple structure, with low costs provides a new thinking for the high-purity 14C isotope of industrial production. Adopt the utility model provides a 14C purity that separation and purification system made is high, can reach more than 90%.

Description

14C isotope's separation and purification system

Technical Field

The utility model belongs to the technical field of 14C isotope separation purification, concretely relates to separation and purification system of 14C isotope.

Background

Carbon exists in various isotopes such as 12C, 13C, 14C and the like in nature, and the relative abundance of 12C and 13C is 98.89 percent and 1.11 percent respectively; 14C is only very trace and radioactive, and has a half-life of 5730 years.

As a radioactive isotope, the 14C isotope is a common source tracing index, can be applied to the fields of detection of helicobacter pylori (Hp), ADME (absorption, distribution, metabolism and excretion) research of medicines, other environmental detection and the like, and has wide application.

The natural radioactive carbon isotope (14C) is mainly derived from the reaction of neutrons generated by cosmic rays in the high-rise atmosphere and the stable nitrogen isotope 14N, and the generated 14C is combined with oxygen in the atmosphere to form carbon dioxide (14 CO)₂) Enters the lower atmosphere, enters the ocean through sea-gas exchange and vertical mixing, and becomes an inorganic carbon source for life activities (such as assimilation of photosynthesis, chemoautotrophy and the like) of land and marine organisms.

However, the content of 14C in nature is very low, and is only 1.2 multiplied by 10^-10% of the total weight of the composition. Prepared from natureThe difficulty of 14C is very high, the input cost of production equipment is high, and the enrichment difficulty is high.

Currently, 14C is produced mainly by irradiating AlN powder target material through a reactor. Such as literature (technical research on preparation of (14) C source material by irradiation of high-purity AlN through Chinese advanced research heap, < annual newspaper of Chinese atomic energy science institute > 2013, period 00). But the productivity is not large, the separation and purification are difficult, and the cost is high. Causing frequent shortages in the market, which in turn leads to high prices for the 14C isotope.

Nuclear power plant reactor fuel produces a large number of fission products during combustion, which produce about 80 radioisotopes. Radioactive elements are still present in high abundance in the waste from nuclear reactors. (Master thesis of dynamics of absorption and accumulation of gaseous 14C by plants.) Nuclear Power plant waste, including waste and waste streams, has 14C nuclide, typically 14C-CH4, 14C-CO₂And the like exist in gas forms, the waste is generally generated by a pressurized water reactor in dozens of Ci every year, and the 14C of Ci is generated by a heavy water reactor in hundreds of Curie every year.

Because of its long half-life and high toxicity, 14C accumulates in the environment causing radiation exposure much greater than noble gases and tritium. At present, the nuclide is mainly directly discharged through effluent, which not only causes radiation hazard to human bodies through various ways, but also causes environmental pollution; but also causes waste of resources.

Therefore, the separation and purification of the 14C isotope from the nuclear reactor waste meets the requirement of green production, and a new way is provided for the preparation of the 14C isotope. And the nuclear reactor has large waste amount and stable supply, so the method is suitable for large-scale industrial production. However, there is no report on this aspect.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems in the prior art, the present invention is directed to a separation and purification system for recovering 14C isotopes from nuclear power plant wastes.

In order to realize the purpose of the utility model, the utility model adopts the following technical scheme:

A14C isotope separation and purification system comprises a gas oxidation system, a primary low-temperature cooling system, a secondary low-temperature cooling system and 14C-CO which are sequentially connected₂A separation and enrichment system is arranged in the separation and enrichment system,

the 14C-CO₂The separation and enrichment system comprises 12C-CO₂/14C-CO₂An exchange tower, a desorption tower and an absorption tower;

the outlet of the secondary cryogenic cooling system is in communication with the 12C-CO₂/14C-CO₂The air inlet of the exchange tower body is connected with the 12C-CO₂/14C-CO₂An outlet at the bottom of the exchange tower is connected with an air inlet of a resolving tower body, an air outlet at the bottom of the resolving tower is connected with an air inlet at the bottom of the absorption tower, and an air outlet at the top of the absorption tower is connected with an air inlet at the top of the exchange tower; the gas outlet at the top of the analysis tower is connected with the gas inlet at the bottom of the exchange tower; and the gas outlet at the top of the exchange tower is connected with the gas inlet of the absorption tower body.

Preferably, the primary cryogenic cooling system comprises a-20 to 0 ℃ cryotrap and a-78.5 to-170 ℃ cryotrap connected in series.

Preferably, the secondary cryogenic cooling system comprises a-77 to 0 ℃ cryotrap, a-78.5 to-170 ℃ cryotrap and a-77 to 0 ℃ cryotrap connected in series. CO cooled by primary low-temperature cooling system₂After entering a secondary low-temperature cooling system, the mixture is evaporated and condensed, and finally evaporated and enters the next process in a gas form.

Preferably, the gas oxidation system is an oxidation bed.

Preferably, an absorption tank is further arranged between the gas oxidation system and the primary low-temperature cooling system, and the absorption tank is connected with the alkali liquor adding device and the acid liquor adding device.

Preferably, an alkaline adsorption resin is further arranged between the gas oxidation system and the primary low-temperature cooling system, and a heating device is arranged outside the adsorption resin. Preferably, the temperature of the heating device is raised to 30-200 ℃.

Firstly, gas enters into alkaline adsorption resin for adsorption, and then CO is heated by raising the temperature to ensure that₂And (6) analyzing.

Compared with the prior art, the beneficial effects of the utility model reside in that:

(1) the utility model provides a retrieve 14C's separation and purification system in follow nuclear power station discarded object, this system simple structure, with low costs provides a new thinking for the high-purity 14C isotope of industrial production.

(2) Adopt the utility model provides a 14C purity that separation and purification system made is high, can reach more than 90%.

Drawings

Fig. 1 is a schematic diagram of the 14C separation and purification system provided in example 1.

Detailed Description

In order to make the objects and technical solutions of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the following embodiments.

Example 1

As shown in FIG. 1, the utility model provides a separation and purification system for retrieving 14C isotope from nuclear power station waste, this separation and purification system is including gas oxidation system, one-level cryogenic cooling system, second grade cryogenic cooling system and 14C-CO who connects gradually₂A separation and enrichment system is arranged in the separation and enrichment system,

the 14C-CO₂The separation and enrichment system comprises 12C-CO₂/14C-CO₂An exchange tower, a desorption tower and an absorption tower;

the outlet of the secondary cryogenic cooling system is in communication with the 12C-CO₂/14C-CO₂The air inlet of the exchange tower body is connected with the 12C-CO₂/14C-CO₂An outlet at the bottom of the exchange tower is connected with an air inlet of a resolving tower body, an air outlet at the bottom of the resolving tower is connected with an air inlet at the bottom of the absorption tower, and an air outlet at the top of the absorption tower is connected with an air inlet at the top of the exchange tower; the gas outlet at the top of the analysis tower is connected with the gas inlet at the bottom of the exchange tower; the gas outlet at the top of the exchange tower is connected with the gas inlet of the absorption tower body;

in this embodiment, the primary cryogenic cooling system comprises a cascadeAnd a low-temperature cold trap at the temperature of-20 to 0 ℃ and a low-temperature cold trap at the temperature of-78.5 to-170 ℃ are connected. The mixed gas is condensed by a low-temperature cold trap at the temperature of between 20 ℃ below zero and 0 ℃ to remove water and SO₂And components with boiling point above-20 deg.C.

Treating the mixed gas by adopting a low-temperature cold trap at the temperature of between-78.5 and-170 ℃ mainly by desublimating CO2 gas into dry ice; the redundant gas is ordinary O2, N2 and other gases, and can be directly discharged.

The secondary low-temperature cooling system comprises a-77-0 ℃ low-temperature cold trap, a-78.5-170 ℃ low-temperature cold trap and a-77-0 ℃ low-temperature cold trap which are sequentially connected. Under the action of a secondary low-temperature cooling system, the desublimated dry ice is heated and evaporated at the temperature of between-77 and 0 ℃ (such as-70 ℃), and nonvolatile components are directly discarded; purification of the gas can then be achieved by equipment desublimation at-78.5 to-170 ℃ (e.g., -80 ℃) and finally by one to multiple back and forth evaporations and desublimation at-77 to 0 ℃ (e.g., -70 ℃).

Pure product 14CO discharged from secondary low-temperature cooling system₂And (4) entering a separation and enrichment system for further separation and enrichment to realize purification. Pure product of 14CO₂The process of achieving further purification in the separation and enrichment system is as follows:

first, the pure product 14CO₂From 12C-CO₂/14C-CO₂The air inlet of the exchange tower body enters the exchange tower,

under the action of catalytic packing in an exchange column, 14C-CO₂With liquid phase R-12CO from the absorption column₂Rapid exchange of exchanged R-14CO₂Moving to the bottom of the tower, entering into a desorption tower, and desorbing the 14CO₂The obtained product enters the exchange tower again, and the resolved liquid absorbent enters the absorption tower to absorb the 12C-CO at the top of the exchange tower₂Then enters the exchange tower again for exchange again. Ultra-pure 14C-CO after multiple exchanges₂And is discharged from the tower body exhaust port of the exchange tower.

The 14C in the waste of the nuclear power station is separated and purified by the embodiment, and 14C-CO is detected₂The purity of (A) is more than 90%.

The above description is only for the embodiments of the present invention, and the description is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several changes and modifications can be made, which all fall within the scope of the present invention.

Claims (6)

1. A14C isotope separation and purification system is characterized by comprising a gas oxidation system, a primary low-temperature cooling system, a secondary low-temperature cooling system and a 14C-CO isotope separation and purification system which are sequentially connected₂A separation and enrichment system is arranged in the separation and enrichment system,

the 14C-CO₂The separation and enrichment system comprises 12C-CO₂/14C-CO₂An exchange tower, a desorption tower and an absorption tower;

the outlet of the secondary cryogenic cooling system is in communication with the 12C-CO₂/14C-CO₂The air inlet of the exchange tower body is connected with the 12C-CO₂/14C-CO₂The outlet at the bottom of the exchange tower is connected with the air inlet of the tower body of the desorption tower, the liquid outlet at the bottom of the desorption tower is connected with the liquid inlet at the bottom of the absorption tower, and the liquid outlet at the top of the absorption tower is connected with the liquid inlet at the top of the exchange tower; the gas outlet at the top of the analysis tower is connected with the gas inlet at the bottom of the exchange tower; and the gas outlet at the top of the exchange tower is connected with the gas inlet of the absorption tower body.

2. The system for separation and purification of a 14C isotope according to claim 1, wherein said primary cryogenic cooling system comprises a-20 to 0 ℃ cryogenic trap and a-78.5 to-170 ℃ cryogenic trap connected in series.

3. The system for separation and purification of 14C isotope according to claim 1, wherein said secondary cryogenic cooling system comprises a-77 to 0 ℃ cryogenic trap, a-78.5 to-170 ℃ cryogenic trap and a-77 to 0 ℃ cryogenic trap connected in series.

4. The system for separation and purification of 14C isotope according to claim 1, wherein said gas oxidation system is an oxidation bed.

5. The system for separating and purifying 14C isotope according to claim 1, wherein an absorption tank is further arranged between the gas oxidation system and the primary cryogenic cooling system, and the absorption tank is connected with an alkali liquor adding device and an acid liquor adding device.

6. The system for separating and purifying a 14C isotope according to claim 1, wherein an alkaline adsorption resin is further arranged between the gas oxidation system and the primary low-temperature cooling system, and a heating device is arranged outside the adsorption resin.

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