CN112174155A

CN112174155A - Carbon-coated lithium orthosilicate tritium breeder and preparation method and preparation device system thereof

Info

Publication number: CN112174155A
Application number: CN202011043544.8A
Authority: CN
Inventors: 向茂乔; 朱庆山; 郑婕; 岳芬
Original assignee: Institute of Process Engineering of CAS; Nanjing Green Manufacturing Industry Innovation Research Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS; Nanjing Green Manufacturing Industry Innovation Research Institute of Process Engineering of CAS
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2021-01-05

Abstract

The invention provides a C-coated Li₄SiO₄A tritium breeder, a preparation method and a preparation device system thereof are disclosed, wherein the preparation method comprises the following steps: (1) make Li₄SiO₄The particles are in a fluidized state in a protective atmosphere; (2) mixing Li on the basis of the continuous operation of the step (1)₄SiO₄Particles and a carbon source gas; (3) obtaining C-coated Li after gas-solid separation₄SiO₄A tritium breeder. The preparation device system comprises a storage bin, a fluidized bed coating device, a tail gas treatment device and a product collection device. The invention overcomes the defect of Li₄SiO₄Corrosion to cladding material, and raising the content of lithium-base ceramic tritium breeder in He-H₂/H₂Stability in an O environment.

Description

Carbon-coated lithium orthosilicate tritium breeder and preparation method and preparation device system thereof

Technical Field

The invention belongs to the technical field of nuclear fusion, relates to a preparation method of an advanced lithium-based ceramic tritium breeder with a core-shell structure, and particularly relates to a C-coated Li₄SiO₄Tritium breeder, preparation method and preparation device system thereof.

Background

With the increasing world energy demand, the consumption rate of fossil energy on the earth is increasing, and the fossil energy is only used by human for about two or three hundred years, thereby bringing a series of increasingly outstanding environmental problems. The nuclear fusion energy has obvious advantages in the aspects of energy storage, cleanness and environmental protection, and is one of the most promising approaches for thoroughly solving the energy problem by human beings. However, the tritium fuel required for nuclear fusion is naturally low in content and must be bombarded by neutrons⁶Material acquisition of Li. Over decades of development, Li is now present₄SiO₄The microsphere is selected as one of candidate materials of the solid tritium breeding cladding due to the excellent characteristics of high Li density, good tritium release performance, large compressive strength, good moisture resistance and the like.

With the continuous and intensive research, people gradually find that Li is preferred in the actual service environment₄SiO₄The microspheres can corrode the clad material, e.g., react with 316 stainless steel, IN625 steel, low activation ferritic martensitic steel RAFM, European-97 steel, or ARAA alloy steel to form brittle Li₅FeO₄，LiCrO₂，LiFeO₂Isooxide corrosion layer, deterioration of mechanical properties of the cladding structure material, especially in He-H₂In the cleaning atmosphere, the corrosion phenomenon is more obvious, and great potential safety hazard is caused to the long-term stable operation of the nuclear reactor.

To solve this problem, the Japanese atomic energy mechanism was designed to have Er₂O₃Coated RAFM Steel (Fusion Eng. Des.87(2012)1777 and 1787), by design of Er₂O₃The coating layer creates a barrier layer between the microsphere and the steel substrate, and blocks Li₄SiO₄And the element between the cladding and the steel matrix diffuses and reacts, so that the safety of the cladding is improved. But as the service time increases, it results from the presence of greater thermal stresses between the oxide and the matrix of the RAFM steelThe coating is easy to fall off.

CN108550404A discloses a fluid state tritium breeding ceramic composite material, which is formed by mixing a liquid phase and a solid phase, and can eliminate the magnetohydrodynamic resistance effect and the corrosion effect on cladding structure materials of the existing liquid metal or molten salt tritium breeding agent, and also can eliminate the problems of low tritium release efficiency, low heat transfer property, fragility, carrier gas channel blockage caused by lithium volatilization and the like. However, the method has higher cost, is difficult to realize large-scale batch production, cannot fundamentally avoid element diffusion between the tritium breeder and the cladding material, and still has the problem of cladding material corrosion after long-term use.

CN110725006A discloses a method for preparing centimeter-level acicular solid tritium breeder lithium titanate single crystals, and the method utilizes a simple fluxing agent method to prepare centimeter-level acicular Li₂TiO₃The solid tritium breeder of the single crystal ensures the element ratio of Li and Ti by accurately controlling the feeding proportion and the cooling rate, and promotes the generation of large-size crystals. Li finally obtained₂TiO₃The single crystal size reaches centimeter level, the crystallization degree is high, the defects are few, and the problem of the existing powder Li is solved₂TiO₃Difficult to study the diffusion and migration process of tritium in crystal grains and Li₂TiO₃The small size of the single crystal is difficult to characterize. However, the solid tritium breeder is in direct contact with the cladding material during use, and the stability of the tritium breeder is affected.

CN108911735A discloses a high sphericity tritium breeder nanostructured lithium titanate ceramic pellet and a preparation method thereof, the preparation method adopts a premixed liquid composed of a high molecular dispersant and deionized water and precursor powder to prepare a slurry with good fluidity, the obtained slurry is further subjected to wet forming and high-temperature sintering to obtain a nano-structured lithium titanate ceramic pellet with high sphericity, which is not only beneficial to filling of a tritium breeder pellet bed and recovery of residual lithium, but also can increase pellet stacking density to obtain a high-lithium density tritium breeder, and can further reduce thermal stress and irradiation cracking conditions of the tritium breeder and prolong the service life of the tritium breeder. However, the invention also has the problem that the lithium titanate ceramic pellets are in direct contact with the cladding material in the use process, so that the phenomenon of corrosion of the cladding material is easily caused.

Therefore, how to further design and optimize a barrier layer between the tritium breeding agent and the cladding material and prevent the tritium breeding agent from directly contacting with the cladding material becomes a problem to be solved urgently in the prior art of the tritium breeding cladding module in the nuclear fusion reactor.

Disclosure of Invention

The invention aims to provide a C-coated Li₄SiO₄Tritium breeder, method and apparatus system for its preparation, which overcomes Li₄SiO₄Corrosion to cladding material, and raising the content of lithium-base ceramic tritium breeder in He-H₂/H₂Stability in an O environment.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a C-coated Li₄SiO₄A method of preparing a tritium proliferator, the method comprising the steps of:

(1) make Li₄SiO₄The particles are in a fluidized state in a protective atmosphere;

(2) mixing Li on the basis of the continuous operation of the step (1)₄SiO₄Particles and a carbon source gas;

(3) obtaining C-coated Li after gas-solid separation₄SiO₄A tritium breeder.

In the present invention, the fluidization state in the step (1) is such that not only Li₄SiO₄The particles are uniformly distributed in the reaction space, and air in the reaction space is removed, so that the reaction between oxygen in the air and the carbon source gas entering subsequently is prevented.

Preferably, the Li in the step (1)₄SiO₄The particles are spherical or spheroidal in shape.

Preferably, the Li₄SiO₄The particles may have an equivalent diameter of 0.1 to 1.2mm, and may be, for example, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm or 1.2mm, but are not limited theretoWhere numerical values are recited, other numerical values within the numerical range not recited are equally applicable.

In the present invention, when said Li is₄SiO₄When the particles are spherical in shape, the equivalent diameter is Li₄SiO₄The actual particle size of the particles; when said Li is₄SiO₄When the particles are spheroidal in shape, the equivalent diameter is Li₄SiO₄The average particle size of the particles.

Preferably, the gas in the protective atmosphere in step (1) comprises any one or a combination of at least two of nitrogen, argon, helium or neon, and typical but non-limiting combinations include a combination of nitrogen and argon, a combination of argon and helium, a combination of helium and neon, a combination of nitrogen, argon and helium, or a combination of argon, helium and neon.

In the present invention, the protective atmosphere may be such that the Li is₄SiO₄The particles keep a fluidized state, and can isolate oxygen in the environment, so that the subsequent C layer can be smoothly coated.

Preferably, the mixing in step (2) is performed by introducing the carbon source gas into the Li₄SiO₄The particles are in a protective atmosphere.

Preferably, the temperature of the mixing in step (2) is 500-900 ℃, for example 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃ or 900 ℃, but is not limited to the recited values, and other unrecited values within the range of values are equally applicable.

Preferably, the mixing time in step (2) is not less than 1min, for example, 1min, 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min, but is not limited to the recited values, and other non-recited values in the range are also applicable.

Preferably, the carbon source gas in step (2) comprises any one or a combination of at least two of methane, ethane, ethylene, acetylene or propylene, and typical but non-limiting combinations include a combination of methane and ethane, a combination of ethane and ethylene, a combination of ethylene and acetylene, a combination of acetylene and propylene, a combination of methane, ethane and ethylene, a combination of ethane, ethylene and acetylene, or a combination of ethylene, acetylene and propylene.

Preferably, the carbon source gas in step (2) is introduced at a flow rate of 50-200mL/min, such as 50mL/min, 60mL/min, 70mL/min, 80mL/min, 90mL/min, 100mL/min, 110mL/min, 120mL/min, 130mL/min, 140mL/min, 150mL/min, 160mL/min, 170mL/min, 180mL/min, 190mL/min or 200mL/min, but is not limited to the values listed, and other values not listed in this range are also applicable.

Preferably, the gas-solid separation method in step (3) comprises any one or a combination of at least two of gravity settling, centrifugal settling or filtration, and typical but non-limiting combinations include a combination of gravity settling and centrifugal settling, a combination of centrifugal settling and filtration, a combination of gravity settling and filtration, or a combination of gravity settling, centrifugal settling and filtration.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(1) making spherical or spheroidal Li with equivalent diameter of 0.1-1.2mm₄SiO₄The particles are in a fluidized state in a protective atmosphere; the gas in the protective atmosphere comprises any one or the combination of at least two of nitrogen, argon, helium or neon;

(2) on the basis of continuously carrying out the step (1), introducing a carbon source gas into Li₄SiO₄The mixing temperature is 500-900 ℃ in the protective atmosphere of the particles, and the mixing time is more than or equal to 1 min; the carbon source gas comprises any one or combination of at least two of methane, ethane, ethylene, acetylene or propylene; the gas introducing speed of the carbon source gas is 50-200 mL/min;

(3) obtaining C-coated Li after gravity settling, centrifugal settling or filtering₄SiO₄A tritium breeder.

In a second aspect, the present invention provides a C-coated Li prepared by the preparation method of the first aspect₄SiO₄Tritium breeder, said C coated Li₄SiO₄The thickness of the C layer of the tritium breeding agent is more than or equal to 1nmExamples of the above-mentioned compounds include 1nm, 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm, 4.5nm and 5nm, but the above-mentioned compounds are not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

In the present invention, the C-coated Li₄SiO₄The tritium breeder departs from the traditional idea of creating a barrier layer by depositing an oxide coating on a cladding material by depositing Li₄SiO₄The surface is provided with a corrosion-resistant and stable C shell, an inert protective layer is formed between the tritium breeder and the cladding material to achieve the purpose of corrosion resistance, and meanwhile, the hydrophobic C film isolates the tritium breeder from H in the scavenging gas₂/H₂The direct contact of O achieves the purpose of improving the stability of the tritium breeder, thereby solving the key problems of coating falling and tritium breeder breakage and finally obtaining the advanced lithium-based ceramic tritium breeder.

In a third aspect, the present invention provides a method for preparing C-coated Li₄SiO₄The device system for the tritium breeder comprises a storage bin, a fluidized bed coating device, a tail gas treatment device and a product collection device;

the storage bin is used for providing Li for the fluidized bed coating device₄SiO₄Particles;

the fluidized bed coating device is used for mixing Li in protective atmosphere₄SiO₄Reacting the particles with a carbon source gas to obtain C-coated Li₄SiO₄A tritium proliferating agent;

the tail gas treatment device is used for removing tail gas generated in the fluidized bed coating device;

the product collecting device is used for collecting the C-coated Li generated in the fluidized bed coating device₄SiO₄A tritium breeder.

Compared with the prior art, the invention has the following beneficial effects:

(1) the inert C film of the present invention blocks Li₄SiO₄The tritium breeder is directly contacted with the cladding material, so that the diffusion and reaction among Li, O, Fe and Cr elements are fundamentally avoided, and the safety of the cladding material is remarkably improved;

(2) the inert C film of the present invention blocks Li₄SiO₄Tritium breeder and H in sweep gas₂/H₂The direct contact of O obviously improves the stability of the proliferation agent in the cladding;

(3) preparation of C-coated Li₄SiO₄The tritium breeding agent has the advantages of simple method, uniform coating layer, controllable thickness, low cost and easy large-scale batch production.

Drawings

FIG. 1 is a schematic diagram of the process for preparing C-coated Li according to the present invention₄SiO₄A device system for tritium breeders;

FIG. 2 is a C-coated Li obtained by the preparation method provided in example 1₄SiO₄EDS profile of tritium breeder;

FIG. 3 is a C-coated Li obtained by the preparation method provided in example 1₄SiO₄SEM images of tritium proliferators.

Wherein: 1-a storage bin; 2-fluidized bed coating device; 3-a tail gas treatment device; 4-product collection device.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The present invention provides a method for preparing C-coated Li as shown in FIG. 1₄SiO₄The device system of tritium breeder, the device system includes feed bin 1, fluidized bed cladding device 2, tail gas processing apparatus 3 and product collection device 4.

In the present invention, the storage bin 1 is used for providing Li for the fluidized bed coating device 2₄SiO₄Particles; the fluidized bed coating device 2 is used for mixing Li in protective atmosphere₄SiO₄Reacting the particles with a carbon source gas to obtain C-coated Li₄SiO₄A tritium breeder, specifically, the fluidized bed coating device 2 is a fluidized bed; the tail gas treatment device 3 is used for treating tail gas generated in the fluidized bed coating device, and specifically, the tail gas treatment deviceSetting 3 as conventional compensation igniting device; the product collecting device 4 is used for collecting the C-coated Li generated in the fluidized bed coating device₄SiO₄Tritium breeder, specifically, product collection device 4 is the storage tank.

Example 1

This example provides a C-coated Li₄SiO₄The preparation method of the tritium breeding agent is carried out in the device system provided by the invention and shown in the figure 1, and comprises the following steps:

(1) spherical Li having a particle diameter of 0.6mm₄SiO₄The particles are in a fluidized state in a protective atmosphere of argon;

(2) on the basis of continuously carrying out the step (1), introducing carbon source gas methane into Li₄SiO₄The mixing temperature of the granules in the protective atmosphere is 800 ℃, and the mixing time is 30 min; the gas introducing speed of the carbon source gas is 125 mL/min;

(3) obtaining C-coated Li after gravity settling₄SiO₄A tritium breeder.

FIG. 2 is a view of the C-coated Li obtained by the preparation method provided in this example₄SiO₄EDS profile of tritium breeder with C content up to 14 at.%.

FIG. 3 is a view of the C-coated Li obtained by the preparation method provided in this example₄SiO₄In the SEM image of the tritium breeding agent, as can be seen from FIG. 3, the surface of the crystal grain of the microsphere is uniformly coated with a layer of nano C film.

The preparation method provided in this example can obtain C-coated Li₄SiO₄The thickness of the C layer of the tritium breeding agent is 2 nm.

Example 2

(1) spheroidal Li having an average particle diameter of 0.9mm₄SiO₄The particles are in a fluidized state in a protective atmosphere of nitrogen;

(2) in step (1) holdOn the basis of the subsequent process, carbon source gas ethane is introduced into Li₄SiO₄The mixing temperature of the granules in the protective atmosphere is 700 ℃, and the mixing time is 45 min; the gas introducing speed of the carbon source gas is 160 mL/min;

(3) obtaining C-coated Li after centrifugal sedimentation₄SiO₄A tritium breeder.

The C-coated Li obtained in this example₄SiO₄The thickness of the C film of the tritium breeder is 2.5nm, and the obtained C is coated with Li₄SiO₄The element composition and the micro-morphology of the tritium breeder are similar to those of example 1, and therefore, the details are not repeated herein.

Example 3

(1) spherical Li having a particle diameter of 0.3mm₄SiO₄The particles are in a fluidized state in a protective atmosphere of helium;

(2) on the basis of continuously carrying out the step (1), introducing carbon source gas ethylene into Li₄SiO₄The mixing temperature of the granules in the protective atmosphere is 600 ℃, and the mixing time is 15 min; the gas introducing speed of the carbon source gas is 85 mL/min;

(3) filtering to obtain C-coated Li₄SiO₄A tritium breeder.

The C-coated Li obtained in this example₄SiO₄The thickness of the C film of the tritium breeder is 1.5nm, and the obtained C is coated with Li₄SiO₄The element composition and the micro-morphology of the tritium breeder are similar to those of example 1, and therefore, the details are not repeated herein.

Example 4

(1) spheroidal Li having an average particle diameter of 1.2mm₄SiO₄GranulesIn a protective atmosphere of neon in a fluidized state;

(2) on the basis of continuously carrying out the step (1), introducing carbon source gas propylene into Li₄SiO₄Mixing the granules in a protective atmosphere at 900 deg.C for 1 min; the gas introducing speed of the carbon source gas is 200 mL/min;

(3) obtaining C-coated Li after gravity settling₄SiO₄A tritium breeder.

The C-coated Li obtained in this example₄SiO₄The thickness of the C film of the tritium breeder is 1nm, and the obtained C is coated with Li₄SiO₄The element composition and the micro-morphology of the tritium breeder are similar to those of example 1, and therefore, the details are not repeated herein.

Example 5

(1) spherical Li having a particle diameter of 0.1mm₄SiO₄The particles are in a fluidized state in a protective atmosphere of argon;

(2) on the basis of continuously carrying out the step (1), introducing carbon source gas acetylene into Li₄SiO₄The mixing temperature of the granules in the protective atmosphere is 500 ℃, and the mixing time is 60 min; the gas introducing speed of the carbon source gas is 50 mL/min;

The C-coated Li obtained in this example₄SiO₄The thickness of the C film of the tritium breeder is 3nm, and the obtained C is coated with Li₄SiO₄The element composition and the micro-morphology of the tritium breeder are similar to those of example 1, and therefore, the details are not repeated herein.

Comparative example 1

This comparative example provides Li₄SiO₄A method for treating a tritium breeding agent, wherein the method is carried out in the device system shown in figure 1, and the method comprises the following steps:

(2) introducing nitrogen into Li on the basis of continuous operation of the step (1)₄SiO₄The mixing temperature of the granules in the protective atmosphere is 800 ℃, and the mixing time is 30 min; the gas introducing speed of the nitrogen is 125 mL/min;

(3) obtaining Li after gravity settling₄SiO₄A tritium breeder.

Li obtained in example 1 and comparative example 1₄SiO₄The tritium proliferator was filled in each container of low activation steel, heated to 650 ℃ under an argon atmosphere and kept at that temperature for 10 days, and then the surface of the low activation steel was analyzed and tested, and as a result, it was found that the container was filled with Li obtained in example 1₄SiO₄Low activation steel with tritium breeder showed no significant corrosion, but was loaded with Li from comparative example 1₄SiO₄The low activation steel of tritium breeder found obvious corrosion, indicating Li₄SiO₄The tritium breeder obviously inhibits the corrosion of low-activation steel after coating a C layer.

It can be seen that the inert C film in the present invention blocks Li₄SiO₄The tritium breeder is directly contacted with the cladding material, so that the diffusion and reaction among Li, O, Fe and Cr elements are fundamentally avoided, and the safety of the cladding material is remarkably improved; the inert C film of the present invention blocks Li₄SiO₄Tritium breeder and H in sweep gas₂/H₂The direct contact of O obviously improves the stability of the proliferation agent in the cladding; preparation of C-coated Li₄SiO₄The tritium breeding agent has the advantages of simple method, uniform coating layer, controllable thickness, low cost and easy large-scale batch production.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims

1. C-coated Li₄SiO₄A process for the preparation of a tritium breeder, characterized in that it comprises the following steps:

(3) obtaining C-coated Li after gas-solid separation₄SiO₄A tritium breeder.

2. The production method according to claim 1, wherein the Li of step (1)₄SiO₄The shape of the particles is spherical or spheroidal;

preferably, the Li₄SiO₄The equivalent diameter of the particles is 0.1-1.2 mm.

3. The method according to claim 1 or 2, wherein the gas in the protective atmosphere of step (1) comprises any one of nitrogen, argon, helium or neon or a combination of at least two thereof.

4. The production method according to any one of claims 1 to 3, wherein the mixing in step (2) is performed by passing the carbon source gas through the Li₄SiO₄The particles are in a protective atmosphere;

preferably, the temperature of the mixing in the step (2) is 500-900 ℃;

preferably, the mixing time of the step (2) is more than or equal to 1 min.

5. The production method according to any one of claims 1 to 4, wherein the carbon source gas of step (2) comprises any one of methane, ethane, ethylene, acetylene or propylene or a combination of at least two thereof.

6. The production method according to any one of claims 1 to 5, wherein the carbon source gas in the step (2) is introduced at a gas flow rate of 50 to 200 mL/min.

7. The process of any one of claims 1 to 6, wherein the gas-solid separation in step (3) comprises any one or a combination of at least two of gravity settling, centrifugal settling or filtration.

8. The method of any one of claims 1 to 7, comprising the steps of:

9. C-coated Li prepared by the preparation method according to any one of claims 1 to 8₄SiO₄Tritium proliferator characterized in that said C coats Li₄SiO₄The thickness of the C layer of the tritium breeding agent is more than or equal to 1 nm.

10. For preparing C-coated Li₄SiO₄The device system for the tritium breeder is characterized by comprising a storage bin, a fluidized bed coating device, a tail gas treatment device and a product collection device;

the storage bin is used for coating the fluidized bedProvision of Li₄SiO₄Particles;