CN117976280A - Method and device for integrating, purifying, trapping and purifying nitrous gases based on tail gas of post-treatment plant - Google Patents
Method and device for integrating, purifying, trapping and purifying nitrous gases based on tail gas of post-treatment plant Download PDFInfo
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- 239000007789 gas Substances 0.000 title claims abstract description 359
- GQPLMRYTRLFLPF-UHFFFAOYSA-N nitrous oxide Inorganic materials [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 title claims abstract description 134
- 238000000034 method Methods 0.000 title claims abstract description 126
- 239000003463 adsorbent Substances 0.000 claims abstract description 51
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 50
- 238000001179 sorption measurement Methods 0.000 claims abstract description 50
- 238000001035 drying Methods 0.000 claims abstract description 47
- 230000008569 process Effects 0.000 claims abstract description 39
- 238000003795 desorption Methods 0.000 claims abstract description 29
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 25
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 25
- 230000002285 radioactive effect Effects 0.000 claims abstract description 25
- 239000007788 liquid Substances 0.000 claims abstract description 18
- 230000008929 regeneration Effects 0.000 claims abstract description 7
- 238000011069 regeneration method Methods 0.000 claims abstract description 7
- 238000009833 condensation Methods 0.000 claims abstract description 5
- 230000005494 condensation Effects 0.000 claims abstract description 5
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 81
- 238000000746 purification Methods 0.000 claims description 64
- 239000002808 molecular sieve Substances 0.000 claims description 61
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 61
- 230000007246 mechanism Effects 0.000 claims description 44
- 238000010438 heat treatment Methods 0.000 claims description 36
- 230000018044 dehydration Effects 0.000 claims description 33
- 238000006297 dehydration reaction Methods 0.000 claims description 33
- 238000001914 filtration Methods 0.000 claims description 27
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
- 229910052680 mordenite Inorganic materials 0.000 claims description 22
- 239000000741 silica gel Substances 0.000 claims description 22
- 229910002027 silica gel Inorganic materials 0.000 claims description 22
- 238000002360 preparation method Methods 0.000 claims description 16
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 claims description 15
- 239000003513 alkali Substances 0.000 claims description 13
- 238000005406 washing Methods 0.000 claims description 12
- 230000001172 regenerating effect Effects 0.000 claims description 11
- 229920006395 saturated elastomer Polymers 0.000 claims description 9
- 239000000443 aerosol Substances 0.000 claims description 6
- 238000010924 continuous production Methods 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 6
- 150000002736 metal compounds Chemical class 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 24
- 239000000941 radioactive substance Substances 0.000 abstract description 14
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 12
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 30
- 239000000047 product Substances 0.000 description 20
- 230000000694 effects Effects 0.000 description 12
- 230000009286 beneficial effect Effects 0.000 description 11
- 239000000203 mixture Substances 0.000 description 10
- 238000003756 stirring Methods 0.000 description 10
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 7
- 239000003546 flue gas Substances 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 230000006837 decompression Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 239000002915 spent fuel radioactive waste Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 3
- 239000006096 absorbing agent Substances 0.000 description 3
- 239000002274 desiccant Substances 0.000 description 3
- 230000018109 developmental process Effects 0.000 description 3
- 229910052707 ruthenium Inorganic materials 0.000 description 3
- 229910052712 strontium Inorganic materials 0.000 description 3
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 3
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- 229910002089 NOx Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910052770 Uranium Inorganic materials 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- NLSCHDZTHVNDCP-UHFFFAOYSA-N caesium nitrate Chemical compound [Cs+].[O-][N+]([O-])=O NLSCHDZTHVNDCP-UHFFFAOYSA-N 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 2
- 239000003758 nuclear fuel Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052792 caesium Inorganic materials 0.000 description 1
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- UUCCCPNEFXQJEL-UHFFFAOYSA-L strontium dihydroxide Chemical compound [OH-].[OH-].[Sr+2] UUCCCPNEFXQJEL-UHFFFAOYSA-L 0.000 description 1
- 229910001866 strontium hydroxide Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention discloses a method and a device for integrating, purifying, trapping and purifying nitrous gases based on tail gas of a post-treatment plant, wherein the method comprises the following steps: 1) Purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas; 2) Drying the low-radioactivity tail gas to obtain a first mixed gas; 3) The first mixed gas is subjected to adsorption removal on the nitrous gas through an adsorbent, and then the adsorbent is subjected to desorption regeneration through pressure swing operation to obtain a mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide; 4) And separating the mixed desorbed gas by adopting a condensation process to respectively obtain liquid nitrous gas and gaseous carbon dioxide. The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for the process point of using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant; the emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Description
Technical Field
The invention belongs to the technical field of spent fuel aftertreatment, and particularly relates to a method and a device for integrating, purifying, trapping and purifying nitrous gases based on tail gas of a aftertreatment plant.
Background
With the continuous expansion of nuclear power scale, the demand for nuclear fuel is increasing, and the well-established uranium ore resource reserves cannot support the development of nuclear power for a long time. The closed circulation of the available nuclear fuel in the spent fuel is realized by constructing a post-treatment plant in China so as to reduce the dependence on import. Advanced spent fuel post-treatment technology must be developed to achieve efficient utilization of uranium resources.
In the post-treatment device of China, a large amount of nitrous gas is used as a decomposing agent of hydrazine, an iodine removing agent and the like. In order to meet the downstream use requirement, china develops a matched nitrous gas preparation technology, and NO x is generated through the reaction of NaNO 2 and HNO 3. However, the product of this technique is NO x, and this technique can produce a large amount of waste liquid as a byproduct. Therefore, there is a need to develop an environment-friendly nitrous gas production technology. Notably, the post-treatment device in China can generate a large amount of tail gas containing nitrogen oxides. The exhaust gas is generally converted into a waste liquid by an absorption method and then treated. Under the background, by simplifying the process flow, the direct recovery of the nitrous gases in the tail gas containing nitrogen oxides of the post-treatment plant for downstream use is particularly important.
The method for directly recovering NO x in the nitrogen oxide tail gas generally adopts an adsorption method, namely, the NO x in the tail gas is enriched through an adsorbent, and the method has high purification efficiency and relatively high operation flexibility, and is one of potential tail gas separation technologies of post-treatment plants.
The application publication number CN 109794137A, named as a method and a system for adsorbing, purifying and enriching and recovering the nitrogen oxides in the flue gas, discloses a method for adsorbing, purifying and enriching and recovering the nitrogen oxides in the flue gas of a steel mill, and uses the flue gas of the steel mill as raw material gas to realize the separation of the nitrogen oxide gas by using a molecular sieve. The technical scheme realizes large adsorption capacity and stable cycle performance, but the composition of flue gas is completely different from that of tail gas of a post-treatment plant in China, and the tail gas of the post-treatment plant cannot be treated.
The application publication No. CN 111603886A, named as a method and a device for recovering NOx in a three-tower switching mode, discloses a method and a device for recovering NOx in flue gas in a three-tower switching mode, however, the technology is too complicated and difficult to be applied to a radioactive spent fuel post-treatment plant.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art, provides a method and a device for integrating, purifying, trapping and purifying nitrous gases based on tail gas of a post-treatment plant, mainly aims at tail gas of the post-treatment plant in China (the composition of the tail gas is very special and is different from that of tail gas of a foreign post-treatment plant), provides high-purity nitrous gas for the downstream, accords with the principle of sustainable development, and has obvious economic benefit.
The technical scheme adopted for solving the technical problem of the invention is to provide a method for integrating, purifying, trapping and purifying nitrous gases based on tail gas of a post-treatment plant, which comprises the following steps:
1) Purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
2) Drying the low-radioactivity tail gas to obtain a first mixed gas;
3) The first mixed gas is subjected to adsorption removal on the nitrous gas through an adsorbent, and then the adsorbent is subjected to desorption regeneration through pressure swing operation to obtain a mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
4) And separating the mixed desorbed gas by adopting a condensation process to respectively obtain liquid nitrous gas and gaseous carbon dioxide.
Preferably, the step 1) is to purify the tail gas of the post-treatment plant, and the specific steps of obtaining the low-radioactivity tail gas are as follows:
The radioactivity level of the tail gas of the post-treatment plant is reduced through primary nuclear level filtration, radioactive liquid drops, radioactive aerosol and particles carried in the tail gas of the post-treatment plant are removed, and then the low-radioactivity tail gas is obtained through purifying, adsorbing and separating the volatile metal compound gas.
Preferably, the adsorbent used in the purification and adsorption in the step 1) is modified USY
The molecular sieve, the step 1) also comprises the preparation of a modified USY molecular sieve, and the preparation method of the modified USY molecular sieve comprises the following steps:
(a) Adding the USY molecular sieve into a mixed solution of sodium hydroxide and tetrapropylammonium hydroxide for alkali treatment to obtain an alkali-treated USY molecular sieve;
(b) Washing and filtering the alkali-treated USY molecular sieve, and then heating to obtain the modified USY molecular sieve.
Preferably, the molar ratio of sodium hydroxide to tetrapropylammonium hydroxide in the step (a) is (1-2): 1, and the concentration of sodium hydroxide is 0.1-1 mol/L.
Preferably, the temperature of the alkali treatment in the step (a) is 45-70 ℃, and the time of the alkali treatment is 1-10 h.
Preferably, the heating temperature in the step (b) is 450 to 650 ℃ and the heating time is 2 to 6 hours.
Preferably, in the step 1), purification and adsorption are performed by using two purification towers, the number of the purification towers is two, the first purification tower is switched after adsorption saturation, and the tail gas is transferred into the other purification tower so as to ensure continuous process; and regenerating the adsorbed and saturated purifying tower in normal temperature and negative pressure mode.
Preferably, the adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is (0.5-2): 1.
Preferably, the drying treatment in the step 2) adopts two dehydration towers, the number of the dehydration towers adopts a double-tower pressure swing adsorption process, the first dehydration tower is switched after adsorption saturation, and the tail gas is transferred into the other dehydration tower so as to ensure continuous process; and regenerating the adsorbed and saturated dehydrating tower in normal temperature and negative pressure mode.
Preferably, the molecular sieve used in the adsorption in the step 3) is a ZSM-5 type molecular sieve.
Preferably, the temperature of the rectification in the step 4) is-65 to-5 ℃ and the pressure is 0.5 to 2MPa.
The invention also provides a device for the method for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant, which comprises the following steps:
The purification mechanism is used for purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
The drying mechanism is connected with the purifying mechanism and is used for drying the low-radioactivity tail gas to obtain a first mixed gas;
The adsorption mechanism is connected with the drying mechanism and is used for adsorbing and removing the nitrous gas from the first mixed gas through the adsorbent, and then desorbing and regenerating the adsorbent through pressure swing operation to obtain mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
And the condensing mechanism is connected with the adsorption mechanism and is used for separating the mixed desorption gas by adopting a condensing process to respectively obtain liquid nitrous gas and gaseous carbon dioxide.
Preferably, the device for the method for purifying, trapping and trapping the nitrous gases based on the tail gas of the post-treatment plant further comprises:
The filtering mechanism is connected with the purifying mechanism and is used for filtering solids in tail gas of a post-treatment plant.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Drawings
FIG. 1 is a schematic structural view of an apparatus used in the method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant in example 2 of the present invention.
In the figure: 1-a metering pump; 2-primary nuclear grade filter; 3-a second condenser; 4-a first buffer tank; 5-a first fan; 6-a first vacuum pump; 7-a purifying tower; 8-a second buffer tank; 9-a second fan; 10-a second vacuum pump; 11-a dehydration tower; 12-a third buffer tank; 13-a third fan; 14-an adsorption tower; 15-a third vacuum pump; a 16-condenser; 17-fourth buffer tank; 18-a transfer pump; 19-gasifier.
Detailed Description
The present invention will be described in further detail below with reference to the drawings and detailed description for the purpose of better understanding of the technical solution of the present invention to those skilled in the art.
Embodiments of the present patent are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present patent and are not to be construed as limiting the present patent.
In the description of this patent, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the patent and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a particular orientation, be configured and operated in a particular orientation, and are therefore not to be construed as limiting the patent.
In the description of this patent, it should be noted that, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "disposed" are to be construed broadly, and may be fixedly connected, disposed, detachably connected, disposed, or integrally connected, disposed, for example. The specific meaning of the terms in this patent will be understood by those of ordinary skill in the art as the case may be.
Example 1
The embodiment provides a method for integrating, purifying, capturing and purifying nitrous gases based on tail gas of a post-treatment plant, which comprises the following steps:
1) Purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
2) Drying the low-radioactivity tail gas to obtain a first mixed gas;
3) The first mixed gas is subjected to adsorption removal on the nitrous gas through an adsorbent, and then the adsorbent is subjected to desorption regeneration through pressure swing operation to obtain a mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
4) And separating the mixed desorbed gas by adopting a condensation process to respectively obtain liquid nitrous gas and gaseous carbon dioxide.
The embodiment also provides a device for the method for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant, which comprises:
The purification mechanism is used for purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
The drying mechanism is connected with the purifying mechanism and is used for drying the low-radioactivity tail gas to obtain a first mixed gas;
The adsorption mechanism is connected with the drying mechanism and is used for adsorbing and removing the nitrous gas from the first mixed gas through the adsorbent, and then desorbing and regenerating the adsorbent through pressure swing operation to obtain mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
And the condensing mechanism is connected with the adsorption mechanism and is used for separating the mixed desorption gas by adopting a condensing process to respectively obtain liquid nitrous gas and gaseous carbon dioxide.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 2
The embodiment provides a method for integrating, purifying, capturing and purifying nitrous gases based on tail gas of a post-treatment plant, which comprises the following steps:
1) Purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
2) Drying the low-radioactivity tail gas, and removing water in the low-radioactivity tail gas to obtain a dried first mixed gas;
3) The method comprises the steps of carrying out adsorption removal on the nitrous gas by an adsorbent in a nitrous gas adsorbent to obtain clean tail gas, and carrying out desorption regeneration on the adsorbent in the nitrous gas adsorbent by pressure swing operation to obtain a mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
4) And further liquefying, separating and purifying the mixed desorption gas by adopting a condensation process to respectively obtain liquid nitrous gas and gaseous carbon dioxide, wherein the liquid nitrous gas and the gaseous carbon dioxide are high-purity products.
The concentration of nitrogen oxides in the tail gas of the post-treatment plant is high (usually 100-1000 times of the concentration of nitrogen oxides in the flue gas), the water content is high, and the tail gas contains various polar molecules such as CO 2 and volatile radionuclide gases (compounds of strontium, cesium and ruthenium and the like), and the gas composition is quite complex. The post-treatment plant tail gas contains radioactive gas and aerosol, and various strong polar molecules and nonpolar molecules exist at the same time.
Preferably, the step 1) is to purify the tail gas of the post-treatment plant, and the specific steps of obtaining the low-radioactivity tail gas are as follows:
The method comprises the steps of filtering the tail gas of the post-treatment plant through a primary nuclear-grade filtering device to reduce the radioactivity level of the tail gas, removing radioactive liquid drops, radioactive aerosol and particles carried in the tail gas of the post-treatment plant, and then purifying, adsorbing and separating volatile metal compound gas to obtain low-radioactivity tail gas.
Preferably, the adsorbent used in the purification and adsorption in the step 1) is a modified USY molecular sieve, the step 1) further comprises preparation of the modified USY molecular sieve, and the preparation method of the modified USY molecular sieve comprises the following steps:
(a) Adding the USY molecular sieve into a mixed solution of sodium hydroxide and tetrapropylammonium hydroxide for alkali treatment to obtain an alkali-treated USY molecular sieve; specifically, 1-5g USY molecular sieve is added into 50-200mL mixed solution of sodium hydroxide and tetrapropylammonium hydroxide with the mol ratio of 1:1, wherein the concentration of the sodium hydroxide is 0.1-1 mol/L;
Stirring for 1-10 h, preferably 8h at a temperature of 45-70deg.C, preferably 65deg.C on a constant temperature magnetic stirrer at a rotation speed of 200-600r/min, preferably 500r/min,
(B) Washing and filtering the alkali-treated USY molecular sieve, drying at 80 ℃ overnight to obtain a sample, placing the sample in a heating furnace such as a muffle furnace, heating to 450-650 ℃ at a heating rate of 5 ℃/min, and keeping for 2-6 h, preferably at 550 ℃ for 5h to obtain the modified USY molecular sieve.
Specifically, the preparation method of the modified USY molecular sieve in the embodiment is as follows:
5g of USY-3 molecular sieve was added to 200mL of a mixture of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1, wherein the concentration of sodium hydroxide was 0.1mol/L. Stirring for 8 hours at the temperature of 65 ℃ on a constant-temperature magnetic stirrer at the rotating speed of 500r/min, washing, filtering and drying the product overnight at the temperature of 80 ℃ to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 550 ℃ at a heating rate of 5 ℃/min, and maintaining for 5 hours to obtain the USY-3-a molecular sieve.
Preferably, the purifying adsorption in the step 1) adopts a purifying tower, and the purifying tower adopts a double-tower pressure swing adsorption process to purify the purified tail gas; the purification towers are in the form of an axial flow or radial flow fixed bed, the number of the used adsorbents is two, the first purification tower is switched after being adsorbed and saturated, and the tail gas enters the other purification tower in turn, so that the continuous process is ensured; and regenerating the adsorbed and saturated purifying tower in normal temperature and negative pressure mode.
Preferably, the adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is (0.5-2): 1.
Specifically, in the embodiment, the adsorbent used for dehydration in the drying treatment in step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of silica gel to mordenite is 1:1.
Preferably, the drying treatment in the step 2) is performed to remove the moisture in the tail gas, a dehydration tower is adopted, a double-tower pressure swing adsorption process is adopted for the dehydration of the purified tail gas, the dehydration tower is in an axial flow or radial flow fixed bed form, the adsorbent is a mixed adsorbent of silica gel and mordenite, the number of the dehydration towers is two, the first dehydration tower is switched after adsorption saturation, and the tail gas is transferred into the other dehydration tower so as to ensure continuous process; and regenerating the adsorbed and saturated dehydrating tower in normal temperature and negative pressure mode.
Preferably, the molecular sieve used in the adsorption in the step 3) is a ZSM-5 type molecular sieve. Specifically, in the step 3), the nitrous adsorbent is in the form of an axial flow or radial flow fixed bed, a plurality of tubes are uniformly arranged in the adsorber, and columnar ZSM-5 molecular sieves (silicon-aluminum mass ratio is 38:1, diameter 3.5mm, length 6 mm), the flue gas enters into a column tube of a nitrous gas absorber to contact with the adsorbent in the adsorption step, and the nitrous gas is adsorbed and purified.
Preferably, the temperature of the rectification in the step 4) is-65 to-5 ℃ and the pressure is 0.5 to 2MPa. In step 4), condensing the mixed desorbed gas obtained in step 3), and introducing the condensed gas into a rectifying device; carbon dioxide in desorption gas is not easy to liquefy, and nitrous gas is easy to liquefy; the separation of the carbon dioxide gas and the nitrous gas liquid with high purity is realized by cooling and pressurizing in the rectification equipment. Wherein, the working temperature interval of the rectifying equipment used for rectification is set to be preferably 45 ℃ below zero, and the working pressure interval is set to be preferably 1.5MPa.
The embodiment also provides a device for the method for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant, which comprises:
The purification mechanism is used for purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
The drying mechanism is connected with the purifying mechanism and is used for drying the low-radioactivity tail gas to obtain a first mixed gas;
The adsorption mechanism is connected with the drying mechanism and is used for adsorbing and removing the nitrous gas from the first mixed gas through the adsorbent, and then desorbing and regenerating the adsorbent through pressure swing operation to obtain mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
And the condensing mechanism is connected with the adsorption mechanism and is used for separating the mixed desorption gas by adopting a condensing process to respectively obtain liquid nitrous gas and gaseous carbon dioxide.
Specifically, in this embodiment, the purifying means includes the purifying column 7, the drying means includes the dehydrating column 11, the adsorbing means includes the adsorbing column 14, and the condensing means includes the first condenser 17.
The dehydration column 11 is connected to the purification column 7, the adsorption column 14 is connected to the dehydration column 11, and the condenser 17 is connected to the adsorption column 14.
The purifying mechanism further comprises a second buffer tank 8, the second buffer tank 8 is arranged between the purifying tower 7 and the dehydrating tower 11, and the second buffer tank 8 is respectively connected with the purifying tower 7 and the dehydrating tower 11.
The drying mechanism further comprises a third buffer tank 12, the third buffer tank 12 is arranged between the dehydration tower 11 and the adsorption tower 14, and the third buffer tank 12 is respectively connected with the dehydration tower 11 and the adsorption tower 14.
The adsorption mechanism further comprises a fourth buffer tank 17, the fourth buffer tank 17 is arranged between the adsorption tower 14 and the condenser 16, and the fourth buffer tank 17 is respectively connected with the adsorption tower 14 and the condenser 16.
The device for the method for integrating, purifying, trapping and purifying the nitrous gases based on the tail gas of the post-treatment plant further comprises: the filtering mechanism is connected with the purifying mechanism and is used for filtering solids in tail gas of a post-treatment plant. The filtering mechanism comprises a primary nuclear grade filter 2.
The filtering mechanism further comprises a first buffer tank 4 and a second condenser 3, the second condenser 3 is connected with the primary nuclear-grade filter 2, and the first buffer tank 4 is respectively connected with the second condenser 3 and the purifying tower 7.
The filtering mechanism further comprises a metering pump 1, and the metering pump 1 is connected with a primary nuclear grade filter 2.
The purifying mechanism further comprises a first fan 5 and a first vacuum pump 6, wherein the first fan 5 is respectively connected with the first buffer tank 4 and the purifying tower 7, and the first vacuum pump 6 is respectively connected with the first buffer tank 4 and the purifying tower 7.
The drying mechanism also comprises a second fan 9 and a second vacuum pump 10, wherein the second fan 9 is respectively connected with the second buffer tank 8 and the dehydration tower 11, and the second vacuum pump 10 is respectively connected with the second buffer tank 8 and the dehydration tower 11.
The adsorption mechanism further comprises a third fan 13 and a third vacuum pump 15, wherein the third fan 13 is respectively connected with the third buffer tank 12 and the adsorption tower 14, and the third vacuum pump 15 is respectively connected with the adsorption tower 14 and the condenser 16.
The condensing mechanism further comprises a delivery pump 18 and a gasifier 19, wherein the delivery pump 18 is connected with the fourth buffer tank 17, and the gasifier 19 is connected with the delivery pump 18.
The process flow is described in detail in connection with fig. 1 as follows:
The exhaust gas from the post-treatment plant generated from the upstream process point is pumped into the primary nuclear filter 2 through the metering pump 1 to reduce the radioactivity level, radioactive liquid drops, radioactive aerosol and particles entrained in the exhaust gas from the post-treatment plant are removed, then the exhaust gas with low radioactivity is obtained through purification, adsorption and separation of volatile metal compound gas, the exhaust gas with low radioactivity enters the first buffer tank 4, the gas in the first buffer tank 4 is driven into the purification tower 7 through the first fan 5, and the decompression operation of the purification tower 7 is realized through the first vacuum pump 6.
The tail gas purified by the purifying tower 7 enters the second buffer tank 8, and the gas in the second buffer tank 8 is driven by the second fan 9 to enter the dehydrating tower 11, (the decompression operation of the dehydrating tower 11 is realized by the second vacuum pump 10).
The tail gas dried by the dehydration tower 11 enters a third buffer tank 12, and the gas in the third buffer tank 12 is driven to enter an adsorption tower 14 by a third fan 13, (the decompression operation of the adsorption tower 14 is realized by a third vacuum pump 15).
The nitrous gas desorbed from the adsorption tower 14 is condensed into liquid by the condenser 16, and then enters the fourth buffer tank 17, and the product is sent into the gasifier 19 by the delivery pump 18 to obtain a gas product. The gaseous product may be fed to a downstream point of use process.
According to the method for purifying, dehydrating and drying the complex tail gas containing radioactivity of the post-treatment plant based on the tail gas of the post-treatment plant, introducing the complex tail gas into an absorber to absorb and recycle the nitrous gas, desorbing and regenerating the absorber in a decompression mode after the absorption is saturated to obtain mixed desorbed gas of the nitrous gas and carbon dioxide, and finally liquefying and separating by a rectification method to obtain a high-purity nitrous gas liquid product and a carbon dioxide gaseous product. The method is used for recovering the nitrous gases in the tail gas of the radioactive post-treatment plant for the first time and using the nitrous gases in the downstream of the post-treatment plant, and accords with the development concept of environmental protection and sustainable chemistry. The method removes radioactive gas and aerosol contained in the raw material gas by filtering, avoids radioactive substances from being discharged to the outside of the system, realizes directional selective adsorption of the nitrous gas and realizes enrichment of the nitrous gas.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 3
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
5g of USY-3 molecular sieve was added to 200mL of a mixture of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1, wherein the concentration of sodium hydroxide was 0.3mol/L. Stirring for 8 hours at the temperature of 65 ℃ on a constant-temperature magnetic stirrer at the rotating speed of 500r/min, washing, filtering and drying the product overnight at the temperature of 80 ℃ to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 550 ℃ at a heating rate of 5 ℃/min, and maintaining for 5 hours to obtain the USY-3-b molecular sieve.
The adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is 2:1.
The rectification temperature in step 4) is-65 ℃ and the pressure is 0.5MPa.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 4
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
5g of USY-3 molecular sieve was added to 200mL of a mixture of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1, wherein the concentration of sodium hydroxide was 0.5mol/L. Stirring for 8 hours at the temperature of 65 ℃ on a constant-temperature magnetic stirrer at the rotating speed of 500r/min, washing, filtering and drying the product overnight at the temperature of 80 ℃ to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 550 ℃ at a heating rate of 5 ℃/min, and maintaining for 5 hours to obtain the USY-3-c molecular sieve.
The adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is 0.5:1.
The rectification temperature in the step 4) is-5 ℃ and the pressure is 2MPa.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 5
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
5g of USY-3 molecular sieve was added to 200mL of a mixture of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1, wherein the concentration of sodium hydroxide was 0.7mol/L. Stirring for 8 hours at the temperature of 65 ℃ on a constant-temperature magnetic stirrer at the rotating speed of 500r/min, washing, filtering and drying the product overnight at the temperature of 80 ℃ to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 550 ℃ at a heating rate of 5 ℃/min, and maintaining for 5 hours to obtain the USY-3-d molecular sieve.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 6
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
5g of USY-3 molecular sieve was added to 200mL of a mixture of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1, wherein the concentration of sodium hydroxide was 0.9mol/L. Stirring for 8 hours at the temperature of 65 ℃ on a constant-temperature magnetic stirrer at the rotating speed of 500r/min, washing, filtering and drying the product overnight at the temperature of 80 ℃ to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 550 ℃ at a heating rate of 5 ℃/min, and maintaining for 5 hours to obtain the USY-3-e molecular sieve.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
The molecular sieves prepared in examples 2-6 are used for an integrated purification, trapping and purification method of nitrous gases based on tail gas of a post-treatment plant, and the method comprises a purification process, a drying process, a recovery process and a rectification process as shown in figure 1. Wherein the post-treatment plant tail gas is a nitrogen oxide tail gas, the nitrogen oxide tail gas (radioactivity 2.0 MBq/Nm) contains 0.003vol% ruthenium tetraoxide, 0.002vol% strontium hydroxide, 0.001vol% cesium nitrate, 2.4vol% nitrogen dioxide, 5vol% carbon dioxide, 8vol% water vapor, and 84.594vol% air.
The purification process is as follows: after 375NL/h of post-treatment plant tail gas is pretreated and separated by a primary nuclear-grade filtering device, the high-boiling radioactive substances are pressurized to 120kPa and introduced into a purifying tower with the temperature of 80 ℃, volatile radioactive ruthenium, strontium and strontium are adsorbed by USY-3-a, USY-3-b, USY-3-c, USY-3-d and USY-3-e molecular sieves filled in the purifying tower, and the regeneration of the molecular sieves in the purifying tower is realized by decompressing to 50 kPa.
The drying process is as follows: the purified tail gas is pressurized to 150kPa and is introduced into a drying tower (dehydration tower) filled with drying agent (the upper half is filled with silica gel, the lower half is filled with mordenite, the volume ratio is 1 to 1) at the temperature of 80 ℃, the water vapor in the tail gas is adsorbed by the drying agent (adsorbent) in a gaseous state, and the drying agent is regenerated by reducing the pressure to 60 kPa.
The recovery process is as follows: the dried tail gas was pressurized to 160kPa and fed into a recovery column (adsorber) packed with a columnar ZSM-5 type molecular sieve (38, 3.5mm diameter, 6mm length) at 30 c, carbon dioxide and nitrous gases were simultaneously adsorbed, and regeneration of the adsorbent was achieved by depressurizing to 0 kPa.
The rectification process is as follows: the desorbed nitrogen dioxide gas and the purge gas enter a condenser to be cooled to 45 ℃ below zero, and are stored in a product tank under pressure, the working pressure is set to be 1.5MPa, and the product tank is introduced into rectifying equipment.
The results of the product index are shown in Table 1.
TABLE 1 product index results
Example 7
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
1g of USY-3 molecular sieve was added to 50mL of a mixed solution of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1, wherein the concentration of sodium hydroxide was 0.2mol/L. Stirring for 10 hours at the temperature of 70 ℃ on a constant temperature magnetic stirrer at the rotating speed of 200r/min, washing, filtering and drying the product at the temperature of 80 ℃ overnight to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 650 ℃ at a heating rate of 5 ℃ per minute, and maintaining for 2 hours to obtain the USY-3-f molecular sieve.
The adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is 2:1.
The temperature of rectification in the step 4) is 65 ℃ below zero and the pressure is 0.1MPa.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 8
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
3g of USY-3 molecular sieve was added to 150mL of a mixture of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1, wherein the concentration of sodium hydroxide was 1mol/L. Stirring for 1h at a rotation speed of 600r/min on a constant temperature magnetic stirrer at 45 ℃, washing, filtering and drying the product at 80 ℃ overnight to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 450 ℃ at a heating rate of 5 ℃/min, and maintaining for 6 hours to obtain the USY-3-g molecular sieve.
The adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is 0.5:1.
The temperature of the rectification in the step 4) is minus 5 ℃ and the pressure is 10MPa.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 9
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
1g of USY-3 molecular sieve was added to 50mL of a mixed solution of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:1.5, wherein the concentration of sodium hydroxide was 0.2mol/L. Stirring for 10 hours at the temperature of 70 ℃ on a constant temperature magnetic stirrer at the rotating speed of 200r/min, washing, filtering and drying the product at the temperature of 80 ℃ overnight to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 650 ℃ at a heating rate of 5 ℃ per minute, and maintaining for 2 hours to obtain the USY-3-h molecular sieve.
The adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is 2:1.
The temperature of rectification in the step 4) is 65 ℃ below zero and the pressure is 0.1MPa.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
Example 10
The present embodiment provides a method for integrated purification, trapping and purification of nitrous gases based on exhaust gas from a post-treatment plant, which is different from the method in embodiment 2 in that:
the preparation method of the modified USY molecular sieve in the step 1) comprises the following steps:
3g of USY-3 molecular sieve was added to 150mL of a mixture of sodium hydroxide and tetrapropylammonium hydroxide in a molar ratio of 1:2, wherein the concentration of sodium hydroxide was 1mol/L. Stirring for 1h at a rotation speed of 600r/min on a constant temperature magnetic stirrer at 45 ℃, washing, filtering and drying the product at 80 ℃ overnight to obtain a sample. And (3) placing the sample in a heating furnace, such as a muffle furnace, heating to 450 ℃ at a heating rate of 5 ℃/min, and maintaining for 6 hours to obtain the USY-3-i molecular sieve.
The adsorbent used for dehydration in the drying treatment process in the step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of the silica gel to the mordenite is 0.5:1.
The temperature of the rectification in the step 4) is minus 5 ℃ and the pressure is 10MPa.
The method and the device for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant in the embodiment have the following beneficial technical effects:
(1) The method can recycle the nitrous gas in the radioactive tail gas of the post-treatment plant, supply the nitrous gas for a process point using the nitrous gas at the downstream of the post-treatment plant, and realize the nitrogen element balance of the post-treatment plant;
(2) The emission level of the tail gas of the post-treatment plant is reduced, the influence of radioactive substances on the environment is reduced, and the nuclides with high added value are recovered.
The molecular sieves prepared in examples 7 to 10 were used in a method for integrated purification, trapping and purification of nitrous gases based on post-treatment plant tail gas, and the results are as follows.
TABLE 2 product index results
| Radioactivity activity | Moisture content | Recovery rate of nitrous gases | |
| USY-3-f | 0 | ～2400ppm | 91％ |
| USY-3-g | 0 | ～2600ppm | 91％ |
| USY-3-h | 0 | ～2200ppm | 92％ |
| USY-3-i | 0 | ～2000ppm | 93％ |
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (13)
1. The method for integrating, purifying, capturing and purifying the nitrous gases based on the tail gas of the post-treatment plant is characterized by comprising the following steps of:
1) Purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
2) Drying the low-radioactivity tail gas to obtain a first mixed gas;
3) The first mixed gas is subjected to adsorption removal on the nitrous gas through an adsorbent, and then the adsorbent is subjected to desorption regeneration through pressure swing operation to obtain a mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
4) And separating the mixed desorbed gas by adopting a condensation process to respectively obtain liquid nitrous gas and gaseous carbon dioxide.
2. The method for purifying and trapping nitrous gases based on exhaust gas of a post-treatment plant according to claim 1, wherein the step 1) is to perform purification treatment on the exhaust gas of the post-treatment plant, and the method for obtaining low-radioactivity exhaust gas specifically comprises the following steps:
The radioactivity level of the tail gas of the post-treatment plant is reduced through primary nuclear level filtration, radioactive liquid drops, radioactive aerosol and particles carried in the tail gas of the post-treatment plant are removed, and then the low-radioactivity tail gas is obtained through purifying, adsorbing and separating the volatile metal compound gas.
3. The method for integrated purification, trapping and purification of nitrous gases based on tail gas of a post-treatment plant according to claim 2, wherein the adsorbent used in the purification and adsorption in the step 1) is a modified USY molecular sieve, the step 1) further comprises preparation of the modified USY molecular sieve, and the preparation method of the modified USY molecular sieve comprises the following steps:
(a) Adding the USY molecular sieve into a mixed solution of sodium hydroxide and tetrapropylammonium hydroxide for alkali treatment to obtain an alkali-treated USY molecular sieve;
(b) Washing and filtering the alkali-treated USY molecular sieve, and then heating to obtain the modified USY molecular sieve.
4. The method for integrated purification, trapping and purification of nitrous gases based on tail gas of a treatment plant according to claim 3, wherein said step (a) has a molar ratio of sodium hydroxide to tetrapropylammonium hydroxide of (1-2): 1 and a concentration of sodium hydroxide of 0.1-1 mol/L.
5. The method for integrated purification, trapping and purification of nitrous gases based on tail gas from a post-treatment plant according to claim 3, wherein the temperature of the alkali treatment in the step (a) is 45-70 ℃, and the time of the alkali treatment is 1-10 h.
6. The method for integrated purification, trapping and purification of nitrous gases based on tail gas from a post-treatment plant according to claim 3, wherein the heating temperature in said step (b) is 450 ℃ to 650 ℃ and the heating time is 2 to 6 hours.
7. The method for purifying and trapping the nitrous gases based on the tail gas of the post-treatment plant according to claim 1, wherein the purifying adsorption in the step 1) adopts two purifying towers, the purifying towers adopt a double-tower pressure swing adsorption process, the first purifying tower is switched after being saturated, and the tail gas is transferred to the other purifying tower for continuous process; and regenerating the adsorbed and saturated purifying tower in normal temperature and negative pressure mode.
8. The method for integrated purification, trapping and purification of nitrous gases based on tail gas from a post-treatment plant according to claim 1, wherein the adsorbent used for dehydration in the drying treatment in step 2) is a mixed adsorbent of silica gel and mordenite, and the volume ratio of silica gel to mordenite is (0.5-2): 1.
9. The method for integrated purification, trapping and purification of nitrous gases based on tail gas of a post-treatment plant according to claim 1, wherein the drying treatment in the step 2) adopts two dehydration towers, the number of the dehydration towers adopts a double-tower pressure swing adsorption process, the first dehydration tower is switched after adsorption saturation, and the tail gas is transferred to the other dehydration tower for continuous process; and regenerating the adsorbed and saturated dehydrating tower in normal temperature and negative pressure mode.
10. The method for integrated purification, trapping and purification of nitrous gases based on tail gas of a post-treatment plant according to claim 1, wherein the molecular sieve used in the adsorption in the step 3) is a ZSM-5 type molecular sieve.
11. The method for integrated purification, trapping and purification of nitrous gases based on tail gas of a post-treatment plant according to claim 1, wherein the temperature of the rectification in the step 4) is-65 to-5 ℃ and the pressure is 0.5 to 2MPa.
12. An apparatus for a method for integrated purification, trapping and purification of nitrous gases based on exhaust gases of a post-treatment plant according to any one of claims 1 to 11, comprising:
The purification mechanism is used for purifying the tail gas of the post-treatment plant to obtain low-radioactivity tail gas;
The drying mechanism is connected with the purifying mechanism and is used for drying the low-radioactivity tail gas to obtain a first mixed gas;
The adsorption mechanism is connected with the drying mechanism and is used for adsorbing and removing the nitrous gas from the first mixed gas through the adsorbent, and then desorbing and regenerating the adsorbent through pressure swing operation to obtain mixed desorption gas, wherein the mixed desorption gas comprises the nitrous gas and carbon dioxide;
And the condensing mechanism is connected with the adsorption mechanism and is used for separating the mixed desorption gas by adopting a condensing process to respectively obtain liquid nitrous gas and gaseous carbon dioxide.
13. The apparatus for the method for integrated purification, trapping and purifying of nitrous gases based on exhaust gas from a post-treatment plant of claim 12, further comprising:
The filtering mechanism is connected with the purifying mechanism and is used for filtering solids in tail gas of a post-treatment plant.
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