CN116469595A - Low-temperature plasma enhanced atmosphere tritium removal device and tritium removal method - Google Patents
Low-temperature plasma enhanced atmosphere tritium removal device and tritium removal method Download PDFInfo
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- CN116469595A CN116469595A CN202310303372.0A CN202310303372A CN116469595A CN 116469595 A CN116469595 A CN 116469595A CN 202310303372 A CN202310303372 A CN 202310303372A CN 116469595 A CN116469595 A CN 116469595A
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- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 title claims abstract description 145
- 229910052722 tritium Inorganic materials 0.000 title claims abstract description 145
- 238000000034 method Methods 0.000 title claims abstract description 18
- 230000003197 catalytic effect Effects 0.000 claims abstract description 50
- 238000006243 chemical reaction Methods 0.000 claims abstract description 47
- 239000003054 catalyst Substances 0.000 claims abstract description 34
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000001301 oxygen Substances 0.000 claims abstract description 30
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 30
- 238000001179 sorption measurement Methods 0.000 claims abstract description 25
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 21
- 230000003647 oxidation Effects 0.000 claims abstract description 16
- 230000002195 synergetic effect Effects 0.000 claims abstract description 15
- 229910000314 transition metal oxide Inorganic materials 0.000 claims abstract description 11
- 239000002086 nanomaterial Substances 0.000 claims abstract description 10
- 238000006555 catalytic reaction Methods 0.000 claims abstract description 6
- 239000007789 gas Substances 0.000 claims description 19
- 229910052751 metal Inorganic materials 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 19
- 239000011248 coating agent Substances 0.000 claims description 13
- 238000000576 coating method Methods 0.000 claims description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- 230000004888 barrier function Effects 0.000 claims description 9
- 239000000919 ceramic Substances 0.000 claims description 9
- 239000002808 molecular sieve Substances 0.000 claims description 8
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 8
- 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 8
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 claims description 6
- 229910002113 barium titanate Inorganic materials 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 abstract description 10
- 229910000510 noble metal Inorganic materials 0.000 abstract description 5
- 238000000678 plasma activation Methods 0.000 abstract description 2
- 238000001994 activation Methods 0.000 abstract 1
- 230000004913 activation Effects 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 11
- 229910052739 hydrogen Inorganic materials 0.000 description 7
- 239000001257 hydrogen Substances 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000003463 adsorbent Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- XLYOFNOQVPJJNP-PWCQTSIFSA-N Tritiated water Chemical compound [3H]O[3H] XLYOFNOQVPJJNP-PWCQTSIFSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 230000010718 Oxidation Activity Effects 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- RGCLLPNLLBQHPF-HJWRWDBZSA-N phosphamidon Chemical group CCN(CC)C(=O)C(\Cl)=C(/C)OP(=O)(OC)OC RGCLLPNLLBQHPF-HJWRWDBZSA-N 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- -1 flange surfaces Chemical compound 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/02—Treating gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/0407—Constructional details of adsorbing systems
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/32—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by electrical effects other than those provided for in group B01D61/00
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/88—Handling or mounting catalysts
- B01D53/885—Devices in general for catalytic purification of waste gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2259/00—Type of treatment
- B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
- B01D2259/818—Employing electrical discharges or the generation of a plasma
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/10—Nuclear fusion reactors
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Analytical Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- High Energy & Nuclear Physics (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
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Abstract
The invention discloses a low-temperature plasma enhanced atmosphere tritium removal device and a tritium removal method. The device comprises a discharge reactor unit and an active oxygen catalytic unit which are arranged in series, wherein tritium-containing atmosphere sequentially passes through the discharge reactor unit and the active oxygen catalytic unit to complete the low-temperature plasma synergistic catalytic reaction. The discharge reactor unit mainly comprises an inner electrode, a reaction tube, an outer electrode, a low-temperature plasma power supply and the like, so as to realize the activation of tritium-containing atmosphere by low-temperature plasma discharge. Transition metal oxides with micro-nano structures are arranged in the reaction tube and the active oxygen catalytic unit. The device cooperates the plasma technology with the transition metal oxide catalyst with the micro-nano structure, so that the tritium conversion efficiency is improved, the noble metal catalyst is not needed, the cost is low, the catalyst is not easy to fall off, and the catalytic efficiency is ensured. The tritium removal method is based on the tritium removal device, and is matched with a cooler and an adsorption bed to realize plasma activation, catalytic oxidation and adsorption, so that the tritium removal efficiency is high.
Description
Technical Field
The invention belongs to the field of atmosphere tritium removal, and particularly relates to a low-temperature plasma enhanced atmosphere tritium removal device and a tritium removal method based on the device.
Background
In tritium-related places, radiation safety protection of atmospheric tritium is an important task. Typically, the safety protection of tritium requires a combination of triple physical containment and tritium removal purification. However, under the normal operation condition of tritium equipment, tritium still permeates through the primary containing shielding layer and enters the secondary containing layer, permeation is particularly remarkable under the condition of higher temperature, a certain amount of tritium can be accumulated in the secondary containing system consisting of a glove box, and therefore a tritium monitoring system and a tritium removal purifying system are usually required to be arranged for secondary containing.
At present, three types of gaseous tritium removal purification systems in tritium-containing facilities mainly comprise membrane separation tritium removal, metal getter tritium removal and catalytic oxidation-adsorption tritium removal. The catalytic oxidation-adsorption tritium removal method is a tritium removal method with high technical maturity and wide application, and particularly has great advantages under the condition of treating atmospheric flow. The technology mainly comprises the steps of catalytically oxidizing tritium gas into tritium water through a reaction bed, and then utilizing a molecular sieve to adsorb and recycle the tritium water.
However, in this technique, the following problems affect the tritium removal efficiency and stability of the atmosphere tritium removal system:
(1) The efficiency is low and the treatment time is long. Because the tritium gas content in the atmosphere is low, the single oxidation efficiency is low, long-time cyclic treatment is needed for improving the oxidation rate, and the efficiency needs to be improved;
(2) The catalyst activity gradually decreases. Because the tritium gas in the atmosphere tritium removal system has larger treatment capacity and faster flow rate, the gas can etch the surface of the catalyst, the surface active metal can fall off, the activity of the catalyst is reduced, and the catalytic effect is affected;
(3) The treatment cost is high. In order to improve the oxidation rate of the atmosphere tritium removal system, a noble metal catalyst is mainly adopted at present, wherein Pt and Pd are noble metals, the use cost is high, and the Pt and Pd can be used as tritium-containing waste during replacement, so that the subsequent treatment cost is increased.
In order to realize efficient atmosphere tritium removal, a new atmosphere tritium removal technology is needed to be developed.
Disclosure of Invention
In order to achieve the purpose, a low-temperature plasma enhanced atmosphere tritium removal device and a tritium removal method are provided.
The low-temperature plasma enhanced atmosphere tritium removal device comprises a discharge reactor unit and an active oxygen catalytic unit connected in series behind the discharge reactor unit, wherein the tritium-containing atmosphere is required to be treated by the discharge reactor unit and the active oxygen catalytic unit in sequence to complete the low-temperature plasma synergistic catalytic reaction;
the discharge reactor unit comprises an inner electrode, a reaction tube and an outer electrode which are coaxially arranged from inside to outside, and the inner electrode, the reaction tube and the outer electrode form a double-medium barrier discharge structure, and a single-side discharge gap of the double-medium barrier discharge structure is less than or equal to 4mm;
the inner electrode comprises a metal electrode and a tubular medium layer coated on the surface of the metal electrode, wherein the tubular medium layer is made of high-strength ceramic or high-strength quartz glass; the metal electrode is connected with a low-temperature plasma power supply; the outer surface of the tubular medium layer is coated with an aluminum oxide tritium-resisting coating;
the reaction tube is a place for tritium removal reaction in atmosphere, and is made of high-strength ceramic or high-strength quartz glass; the two ends of the reaction tube and the inner electrode are connected with flanges in a sealing way, and the flanges are made of high-strength ceramic or high-strength quartz glass; an air inlet channel is arranged in the flange at one end, and an air outlet channel is arranged in the flange at the other end and is respectively used for injecting tritium-containing atmosphere and discharging the atmosphere after discharge reaction treatment; the surface of the flange, which contacts with tritium-containing atmosphere, and the inner surface of the reaction tube are coated with an aluminum oxide tritium-resisting coating;
a catalyst is arranged in the reaction tube, and the catalyst is a transition metal oxide which takes one or more of triangle spiral, dickson ring or small balls as a carrier and grows a micro-nano structure on the surface of the carrier;
the external electrode is arranged on the outer surface of the reaction tube in a coating manner, and is grounded;
the active oxygen catalytic unit comprises an active oxygen catalytic unit shell and a catalyst which is arranged in the active oxygen catalytic unit shell and is the same as that in the reaction tube.
The low-temperature plasma power supply is connected, the power supply type is a direct-current high-frequency, alternating-current high-frequency, modulated pulse or pulse power supply, and the output voltage is 3 kV-15 kV; wherein, the frequency of the modulated pulse or the pulse power supply is adjustable from 1kHz to 30kHz, and the duty ratio is adjustable from 1 percent to 99 percent.
Optionally, the tritium-resistant coating of the aluminum oxide is less than or equal to 2mm.
Optionally, the carrier size of the catalyst is less than or equal to half of the unilateral discharge gap; the transition metal oxide is Co, mn or Ni oxide, and the micro-nano structure is needle-shaped, cluster-shaped, saw tooth flake-shaped or ribbon-shaped, etc.
Optionally, the double-dielectric barrier discharge structure in the low-temperature plasma enhanced atmosphere tritium removal device is arranged in an array manner, a shell is further arranged outside the double-dielectric barrier discharge structure arranged in the array manner, an air inlet is formed in one end of the shell, which is located in the air inlet channel, and an air outlet is formed in one end of the shell, which is located in the air outlet channel; the inner surface of the shell is provided with an alumina tritium-resisting coating.
A method for removing tritium in a low-temperature plasma enhanced atmosphere, comprising the following steps:
s10, removing particles and organic matters in tritium-containing gas, and purifying the tritium-containing atmosphere;
s20, pumping air by using a dry pump;
s30, monitoring tritium content of tritium-containing gas in an ionization chamber;
s40, controlling the mass flow of the tritium-containing atmosphere, and injecting the tritium-containing atmosphere into a low-temperature plasma enhanced atmosphere tritium removal device;
s50 tritium-containing gas plasma synergistic catalytic oxidation and conventional catalytic oxidation two-stage reaction
Firstly, carrying out plasma synergistic catalytic oxidation reaction, and then carrying out conventional catalytic oxidation; the low-temperature plasma enhanced atmosphere tritium removal device is also filled with barium titanate with high dielectric constant material;
s60, heat exchange is carried out to normal temperature or below
Tritiated steam discharged from the low-temperature plasma enhanced atmosphere tritium removal device is subjected to heat exchange to normal temperature or below through a cooler;
s70 adsorption by adsorption bed
Passing the mixed atmosphere through an adsorption bed, wherein the adsorption bed is a molecular sieve adsorption bed or a cold trap or a combination of the molecular sieve adsorption bed and the cold trap;
s80, monitoring the ionization chamber, discharging the ionization chamber after reaching standards, and otherwise, continuously circularly removing tritium.
The invention has the beneficial effects that: (1) The plasma technology is introduced into the atmosphere tritium removal, so that the process of 'plasma activation + catalytic oxidation + adsorption' atmosphere tritium removal is realized, the treatment efficiency of atmosphere tritium removal is greatly improved, the time and the cost are saved, the method is particularly suitable for nuclear emergency and other scenes, and the final treatment product is more environment-friendly; (2) The plasma technology is cooperated with the modified micro-nano structure transition metal oxide catalyst, so that the tritium conversion efficiency is improved, noble metal is not needed as a catalyst, and the cost is low. The catalyst can be used for a long time, the problems of performance reduction and the like caused by falling of the catalyst are avoided, the performance is extremely stable, and the catalyst can be used for a long time; (3) After the plasma technology is introduced, a temperature control unit is not needed, and the atmosphere tritium removal reaction can be started and stopped immediately.
Drawings
FIG. 1 is a schematic diagram of a low temperature plasma enhanced atmosphere tritium removal device;
FIG. 2 is a diagram of a low temperature plasma enhanced atmosphere tritium removal device A-A;
FIG. 3 is a schematic diagram of a multi-tube array type low-temperature plasma enhanced atmosphere tritium removal device;
FIG. 4 is a diagram of a multi-tube array type low temperature plasma enhanced atmosphere tritium removal device B-B;
FIG. 5 is a micro-nano structured electron microscope image;
FIG. 6 is an atmospheric tritium removal processing system;
FIG. 7 is a tritium removal efficiency curve;
in the figure:
100. a discharge reactor unit; 200. an active oxygen catalytic unit;
1. an inner electrode; 2. a reaction tube; 3. an external electrode; 4. a flange; 5. a low temperature plasma power supply; 6. a catalyst; 7. a housing; 8. a baffle; 9. a catalytic oxidation unit;
11. a metal electrode; 12. a tubular dielectric layer;
31. a filter; 32. a first buffer tank; 33. an air pump; 34. a first ionization chamber; 35. a mass flow controller; 36. tritium is removed in the first low-temperature plasma enhanced atmosphere; 37. tritium is removed in the second low-temperature plasma enhanced atmosphere; 38. a cooler; 39. two first adsorption beds arranged in parallel; 40. a second adsorbent bed; 41. a second ionization chamber; 42. and a second buffer tank.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without creating effort for a person skilled in the art.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the detailed description and fig. 1 to 5.
Example 1
FIGS. 1-2 illustrate a single tube low temperature plasma enhanced atmosphere tritium removal device. The low-temperature plasma enhanced atmosphere tritium removal device comprises a discharge reactor unit 100 and an active oxygen catalytic unit 200 connected in series behind the discharge reactor unit 100, wherein the tritium-containing atmosphere is sequentially processed by the discharge reactor unit 100 and the active oxygen catalytic unit 200 to complete the low-temperature plasma synergistic catalytic reaction. The active oxygen catalytic unit 200 is provided here, and is mainly to further oxidize the atmosphere tritium by further utilizing the ozone and the active material generated by the discharge reactor unit, and finally further purify the residual ozone and trace tritium.
As can be seen from fig. 1 and 2, the overall appearance of the discharge reactor unit 100 is a column structure. The discharge reactor unit comprises an inner electrode 1, a reaction tube 2 and an outer electrode 3 which are coaxially arranged from inside to outside, and the three components form a double-medium barrier discharge structure. Wherein the discharge gap of one side is less than or equal to 4mm.
The inner electrode comprises two parts: the tubular medium layer 12 made of high-strength ceramic or high-strength quartz glass and the metal electrode 11 positioned in the tubular medium layer can withstand air pressure of more than or equal to 0.15MPa, and the tubular medium layer 12 is not damaged. The metal electrode 11 located in the tubular dielectric layer 12 is connected to the low temperature plasma power supply 5. The metal electrode 11 may be made of a metal material such as copper or tungsten. The low-temperature plasma power supply 5 generally selects direct-current high-frequency, alternating-current high-frequency, modulation pulse and pulse power supply, and the output voltage is 3 kV-10 kV, wherein the input voltage, frequency and duty ratio of the low-temperature plasma power supply 5 can be regulated and controlled.
The reaction tube is used as a place for the tritium removal reaction in the atmosphere, and is made of high-strength ceramic or high-strength quartz glass; flanges which are also high-strength ceramics or high-strength quartz glass are respectively arranged at the two ends of the reaction tube and the inner electrode and are used for sealing the space between the reaction tube and the inner electrode. As shown in fig. 1, a channel for injecting tritium-containing gas is provided in the flange 4 at the left end, and a channel for exhausting the treated atmosphere is provided in the flange 4 at the right end. A catalytic transition metal oxide, for example, an oxide of Co, mn or Ni is provided in the reaction tube 2. These transition metal oxides are supported on one or more of deltoid spirals, rings or pellets and grown on the support in the form of needle, plexus, saw tooth sheets or wire ribbon micro-nano structures as shown in fig. 5. The external dimensions of the triangle spiral, the Dixon ring and the small ball are not more than half of the discharge gap of the single side.
The outer electrode is coated on the outer surface of the reaction tube and well grounded.
The active oxygen catalytic unit 200 comprises an active oxygen catalytic unit shell 201 and a catalyst 6 which is arranged in the active oxygen catalytic unit shell 201 and is the same as that in the reaction tube 2, and the active oxygen catalytic unit 200 is also provided with a channel for exhausting gas and is used for exhausting the atmosphere which is subjected to the low-temperature plasma synergistic catalytic reaction.
In order to prevent tritium permeation, a tritium-resisting alumina coating layer is arranged on the inner surface of the reaction tube 2, the outer surface of the tubular medium layer 12 and the surface of the flange which can be contacted with tritium, and the thickness is less than or equal to 2mm.
When a variety of low temperature plasma sources are selected, for example, a DC high frequency source, a modulated pulsed source, a pulsed source, etc., may be selected to provide the energy required for the reaction. However, the electric field applied to the reactor needs to be controlled within 3-15 kV, and the too high voltage is unfavorable for oxidation reaction, otherwise, water molecules are ionized and decomposed.
Example 2
FIGS. 3-4 illustrate a multi-tube array type low temperature plasma enhanced atmosphere tritium removal structure. In this structure, 3×3 array type discharge reactor units described in example 1 are included, and an active oxygen catalyst unit 200 is disposed in series after the array type discharge reactor units. The tritium-containing atmosphere is first treated by an array of discharge reactor units and then discharged to the active oxygen catalytic unit 200 for further reaction. The active oxygen catalytic unit 200 is also provided with a catalyst 6 as in example 1, with a metal housing 7 of a cubic structure outside the 3×3 array arrangement. An aluminum oxide tritium-resistant coating grows on the inner surface of the metal shell to prevent tritium-containing components from penetrating out of the reactor. The 3 x 3 discharge reactor unit is positionally arranged and fixed by a baffle plate 8 provided inside the metal casing. All the metal electrodes can be connected with a low-temperature plasma power supply singly or after being connected in series, and all the external electrodes are well grounded. In order to prevent tritium permeation, a tritium-resistant coating of aluminum oxide is arranged on all surfaces possibly contacting tritium, such as flange surfaces, high-voltage connecting wires between metal electrodes and a power supply, and the like.
The low-temperature plasma technology introduced in the embodiment 1 and the embodiment 2 is a discharge technology, and a physical operation mechanism of the low-temperature plasma technology is to apply a certain alternating high-voltage electric field in a reaction cavity so as to accelerate electrons in atmosphere and realize electron avalanche, so that reaction components reach a low-temperature plasma state, extremely high reactivity is obtained, and chemical reaction is realized. In the hydrogen isotope catalytic oxidation reaction participated by low-temperature plasma, the gaseous tritium molecules can be activated to promote the oxidation activity, and O with high activity is generated by the action of oxygen in the air and the like 3 ，O 2 - And a plurality of active oxides. To further utilize O 3 ，O 2 - The oxidation activity of the isoactive oxide on hydrogen isotopes (mainly residual tritium) and also for the elimination of O 3 The influence on the environment is that an active oxygen catalytic unit is connected in series behind the discharge reactor unit, a catalyst is arranged inside the active oxygen catalytic unit, and finally O is formed 3 And trace tritium are further purified.
In terms of catalyst use, neither the catalysts in example 1 nor example 2 supported any noble metal. In order to ensure the catalytic effect and ensure the uniform discharge in the reactor, all catalysts are prepared by taking one or more of triangle spiral, dixon ring or small balls as a carrier and growing micro-nano structured transition metal oxides on the surface of the carrier through surface modification, wherein the transition metal oxides are mainly micro-nano oxides of transition metals such as Co, mn, ni and the like. In addition, to further optimize the discharge performance, the catalyst may be mixed with particulate barium titanate and particles of a high dielectric constant material. The same granular barium titanate and high dielectric constant material particles also need to be subjected to surface modification treatment, so that the surface of the granular barium titanate and high dielectric constant material particles needs to closely grow a metal oxide micro-nano structure. The pure metal type catalyst cannot be directly used.
In addition, for the single tube type structure in example 1, in order to observe the internal discharge condition conveniently, ensure the safety of tritium and reduce the possibility of permeation, the external structure can refer to a multi-tube type discharge reactor structure, a metal shell is also arranged outside a single discharge reactor unit, the 3×3 array in fig. 3 is changed into a single reaction unit, and an alumina tritium-resisting coating is also arranged inside the shell. In order to facilitate observation of the discharge condition in the reaction tube, a video probe can be installed in the shell to observe the discharge condition. In addition, the discharge reactor unit can be combined with a heat exchanger to transfer the redundant heat energy to the active oxygen catalytic unit so as to improve the catalytic capacity of the active oxygen catalytic unit.
Example 3
Based on the apparatus of examples 1 and 2, a low temperature plasma enhanced atmosphere tritium removal method is presented herein. The tritium removal method requires the use of an atmosphere tritium removal treatment system as shown in FIG. 6. The system sequentially comprises: the device comprises a filter 31, a first buffer tank 32, an air pump 33, a first ionization chamber 34, a mass flow controller 35, two first low-temperature plasma enhanced atmosphere tritium removal 36, a second low-temperature plasma enhanced atmosphere tritium removal 37 which are arranged in parallel, a cooler 38, two first adsorption beds 39, second adsorption beds 40, a second ionization chamber 41 and a second buffer tank 42 which are arranged in parallel. Wherein V1-V16 are pneumatic valves.
When the atmosphere tritium removal is carried out, the method mainly comprises the following steps:
s10, performing tritium-containing atmosphere treatment, enabling the tritium-containing atmosphere to enter the system from an air inlet by starting a dry pump, filtering dust and organic matters in the tritium-containing atmosphere to be treated through a filter 31, purifying the tritium-containing atmosphere, and then entering a first buffer tank 32.
S20, pumping air by using an air pump 33, wherein the air pump 33 is a dry pump, and a mechanical pump is strictly forbidden.
S30 uses the first ionization chamber 34 to monitor the tritium content of the tritium-containing gas.
S40, controlling the mass flow of the tritium-containing atmosphere through a mass flow controller 35, and injecting the tritium-containing atmosphere into a first low-temperature plasma enhanced atmosphere tritium removal device 36 or a first low-temperature plasma enhanced atmosphere tritium removal device 37; the low-temperature plasma enhanced atmosphere tritium removal device is one-by-one, is convenient to replace and maintain, and can be used alternately to increase the working time.
S50 tritium-containing gas plasma synergistic catalytic oxidation and conventional catalytic oxidation two-stage reaction
The plasma is used for synergistic catalytic oxidation reaction, then conventional catalytic oxidation is carried out, tritium-containing atmosphere reacts with oxygen under the synergistic effect of low-temperature plasma and a catalyst, and tritiated water vapor is oxidized.
S60, heat exchange is carried out to normal temperature or below
Tritiated water vapor discharged from the low-temperature plasma enhanced atmosphere tritium removal device is subjected to heat exchange to normal temperature or below, for example, below 10 ℃ through a cooler.
S70 adsorption by adsorption bed
The mixed atmosphere is passed through either a first adsorbent bed 39 or a second adsorbent bed 40, which is a molecular sieve adsorbent bed or a cold trap, or a combination of both. The adsorption bed is one-use and one-standby, is convenient to replace and ensures that tritiated water can be effectively adsorbed during use. The adsorption bed adopts a water cooling or electric to cold method, so that the temperature in the bed reaches 0-3 ℃. Taking a molecular sieve adsorption bed as an example, the built-in molecular sieve can efficiently adsorb water in the atmosphere, thereby realizing recovery of tritium in the atmosphere and purification of the atmosphere.
S80 detects the concentration of the purged atmosphere using the second ionization chamber 41, and finally discharges into the space. The ionization chamber is monitored and discharged to standard, otherwise, the gas is input into the first buffer tank 32 to continue to circularly remove tritium.
In order to further optimize the discharge performance, barium titanate with high dielectric constant material is also mixed in the low-temperature plasma enhanced atmosphere tritium removal device.
The system mainly adopts a built-in or pipeline circulation mode to treat the glove box or the workshop. The built-in type is to arrange the system in a glove box or a room, and due to the small volume, the system can circularly exhaust and treat the interior of the glove box without adding external gas, and is convenient to use. The pipeline circulation means that the system does not enter a glove box or a room, and is connected with the glove box and the like through the gas input and output pipes, so that atmosphere circulation treatment in the space is realized, no extra atmosphere is required to be introduced, and the gas treatment capacity is reduced.
After the low-temperature plasma technology is introduced and the catalyst is optimized, the synergistic effect of the low-temperature plasma and the catalyst is realized, and the conversion efficiency of the hydrogen isotope is greatly improved. Fig. 7 shows the performance curve of oxidizing hydrogen by the low-temperature plasma synergistic dirk ring catalyst after the surface of different dirk rings is grown and oxidized, and it can be seen from the graph that the oxidized dirk ring has hydrogen oxidizing capability, and when the micro-nano structure of the surface is grown, the hydrogen oxidizing capability is rapidly improved to 99%, so that the high-efficiency oxidation of hydrogen isotopes (tritium gas) can be greatly realized by the low-temperature plasma synergistic catalytic reaction.
Claims (5)
1. The low-temperature plasma enhanced atmosphere tritium removal device is characterized by comprising a discharge reactor unit and an active oxygen catalytic unit connected in series behind the discharge reactor unit, wherein the tritium-containing atmosphere is required to be treated by the discharge reactor unit and the active oxygen catalytic unit in sequence to complete the low-temperature plasma synergistic catalytic reaction;
the discharge reactor unit comprises an inner electrode, a reaction tube and an outer electrode which are coaxially arranged from inside to outside, and the inner electrode, the reaction tube and the outer electrode form a double-medium barrier discharge structure, and a single-side discharge gap of the double-medium barrier discharge structure is less than or equal to 4mm;
the inner electrode comprises a metal electrode and a tubular medium layer coated on the surface of the metal electrode, wherein the tubular medium layer is made of high-strength ceramic or high-strength quartz glass; the metal electrode is connected with a low-temperature plasma power supply; the outer surface of the tubular medium layer is coated with an aluminum oxide tritium-resisting coating;
the reaction tube is a place for tritium removal reaction in atmosphere, and is made of high-strength ceramic or high-strength quartz glass; the two ends of the reaction tube and the inner electrode are connected with flanges in a sealing way, and the flanges are made of high-strength ceramic or high-strength quartz glass; an air inlet channel is arranged in the flange at one end, and an air outlet channel is arranged in the flange at the other end and is respectively used for injecting tritium-containing atmosphere and discharging the atmosphere after discharge reaction treatment; the surface of the flange, which contacts with tritium-containing atmosphere, and the inner surface of the reaction tube are coated with an aluminum oxide tritium-resisting coating;
a catalyst is arranged in the reaction tube, and the catalyst is a transition metal oxide which takes one or more of triangle spiral, dickson ring or small balls as a carrier and grows a micro-nano structure on the surface of the carrier;
the external electrode is arranged on the outer surface of the reaction tube in a coating manner, and is grounded;
the active oxygen catalytic unit comprises an active oxygen catalytic unit shell and a catalyst which is arranged in the active oxygen catalytic unit shell and is the same as that in the reaction tube.
The low-temperature plasma power supply is connected, the power supply type is a direct-current high-frequency, alternating-current high-frequency, modulated pulse or pulse power supply, and the output voltage is 3 kV-15 kV; wherein, the frequency of the modulated pulse or the pulse power supply is adjustable from 1kHz to 30kHz, and the duty ratio is adjustable from 1 percent to 99 percent.
2. The low temperature plasma enhanced atmosphere tritium removal device of claim 1, wherein the aluminum oxide tritium-resistant coating is less than or equal to 2mm.
3. The low temperature plasma enhanced atmosphere tritium removal device of claim 1, wherein the catalyst has a carrier size less than or equal to half of a single side discharge gap; the transition metal oxide is Co, mn or Ni oxide, and the micro-nano structure is needle-shaped, cluster-shaped, saw tooth flake-shaped or ribbon-shaped, etc.
4. The low-temperature plasma enhanced atmosphere tritium removal device according to claim 1, wherein the plurality of double-dielectric barrier discharge structures in the low-temperature plasma enhanced atmosphere tritium removal device are arranged in parallel in an array manner, a shell is further arranged outside the double-dielectric barrier discharge structures arranged in the array manner, an air inlet is formed in one end of the shell, which is located in an air inlet channel, and an air outlet is formed in one end of the shell, which is located in an air outlet channel; the inner surface of the shell is provided with an alumina tritium-resisting coating.
5. A tritium removal method based on the low temperature plasma enhanced atmosphere tritium removal device as claimed in any one of claims 1 to 4, characterized in that the tritium removal method comprises the following steps:
s10, removing particles and organic matters in tritium-containing gas, and purifying the tritium-containing atmosphere;
s20, pumping air by using a dry pump;
s30, monitoring tritium content of tritium-containing gas in an ionization chamber;
s40, controlling the mass flow of the tritium-containing atmosphere, and injecting the tritium-containing atmosphere into a low-temperature plasma enhanced atmosphere tritium removal device;
s50 tritium-containing gas plasma synergistic catalytic oxidation and conventional catalytic oxidation two-stage reaction
Firstly, carrying out plasma synergistic catalytic oxidation reaction, and then carrying out conventional catalytic oxidation; the low-temperature plasma enhanced atmosphere tritium removal device is also filled with barium titanate with high dielectric constant material;
s60, heat exchange is carried out to normal temperature or below
Tritiated steam discharged from the low-temperature plasma enhanced atmosphere tritium removal device is subjected to heat exchange to normal temperature or below through a cooler;
s70 adsorption by adsorption bed
Passing the mixed atmosphere through an adsorption bed, wherein the adsorption bed is a molecular sieve adsorption bed or a cold trap or a combination of the molecular sieve adsorption bed and the cold trap;
s80, monitoring the ionization chamber, discharging the ionization chamber after reaching standards, and otherwise, continuously circularly removing tritium.
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