CN110634586B - Method and system for treating radioactive organic waste by using three-phase fluidized bed - Google Patents

Method and system for treating radioactive organic waste by using three-phase fluidized bed Download PDF

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CN110634586B
CN110634586B CN201910899802.3A CN201910899802A CN110634586B CN 110634586 B CN110634586 B CN 110634586B CN 201910899802 A CN201910899802 A CN 201910899802A CN 110634586 B CN110634586 B CN 110634586B
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fluidized bed
organic waste
waste
reaction
radioactive
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CN110634586A (en
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林力
章航洲
李文钰
祝杰
骆枫
梁毅
马兴均
张劲松
陈莉
李振臣
陈先林
高峰
段治强
刘文磊
廖俊喃
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Nuclear Power Institute of China
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    • 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
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • 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
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/16—Processing by fixation in stable solid media
    • G21F9/162—Processing by fixation in stable solid media in an inorganic matrix, e.g. clays, zeolites
    • 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
    • G21F9/04—Treating liquids
    • G21F9/20—Disposal of liquid waste
    • 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
    • G21F9/28—Treating solids
    • G21F9/30—Processing
    • 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
    • G21F9/28—Treating solids
    • G21F9/30—Processing
    • G21F9/301—Processing by fixation in stable solid media
    • G21F9/302—Processing by fixation in stable solid media in an inorganic matrix
    • 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
    • G21F9/28—Treating solids
    • G21F9/34—Disposal of solid waste

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Abstract

The invention discloses a method and a system for treating radioactive organic waste by using a three-phase fluidized bed, which comprises the following steps: (a) filling a fluidized substrate and a catalyst in the three-phase fluidized bed; (b) introducing radioactive organic waste into a three-phase fluidized bed, and simultaneously introducing a metal ion mineralizer, superheated steam, charcoal and air; (c) the radioactive metal ions in the radioactive organic waste are subjected to mineralization containing reaction in the fluidized bed reaction section to generate a mineralization product, and nuclides are contained in the mineralization product; (d) carrying out steam reforming reaction on organic components in the radioactive organic waste in a reaction section of the fluidized bed to produce combustible small molecule gas; (e) the mineralized product is separated. The invention is used for solving the defects of organic radioactive waste treatment modes in the prior art, realizing the treatment of various radioactive organic wastes, and realizing the purposes of reducing the volume to a greater degree and carrying out mineralization containment on unstable pollutant nuclide contained in the radioactive organic wastes.

Description

Method and system for treating radioactive organic waste by using three-phase fluidized bed
Technical Field
The invention relates to the field of nuclear chemical industry, in particular to a method and a system for treating radioactive organic waste by utilizing a three-phase fluidized bed.
Background
Nuclear reactors inevitably produce large quantities of radioactive solid waste during operation and maintenance, including: ion exchange resin, active carbon, filter cores, sludge, waste oil, waste organic solvent, labor protection supplies, plastic cloth, wiping decontamination supplies and the like generated by daily maintenance. Most of the wastes are organic wastes, and the conventional physical treatment can only realize the waste preparation in a short time, but cannot ensure the safety of long-term disposal. Although new nuclear power plants have improved the introduction of waste treatment technologies, such as new technologies for resin treatment, they still do not fundamentally solve the objectives of safe waste treatment and disposal and volume reduction.
The ion exchange resin is one of the most difficult radioactive wastes to treat in a pressurized water reactor nuclear power station, the radioactivity level of the ion exchange resin is high and can reach the middle radioactivity level, the main components are styrene and divinylbenzene cross-linked polymer which is used as a framework, and sulfonated or aminated styrene resin with a three-dimensional network structure is stable in structure and difficult in change of physical and chemical forms, most pressurized water reactor power stations in the world adopt physical methods to treat waste resins, but the long-term safety evaluation of the methods is uncertain.
The most common resin treatment means of domestic pressurized water reactor power stations is cement solidification, the principle of cement solidification is a method for solidifying wastes based on hydration and hydraulic gelation of cement, cement is used as an inorganic cementing material, and a hard cement solidified body is formed after hydration reaction, so that radioactive nuclide is solidified in the cement solidified body, and the nuclide is prevented from being leached out. The method can realize the fixation of the resin and the contained radioactive nuclide in a short time, but as time goes on, the resin is degraded by irradiation and the cement structure is possibly changed to cause the instability of a solidified body, and in addition, the outer packaging container is failed, so that the risk of nuclide migration exists, and the long-term safe disposal is not facilitated; on the other hand, the cement solidification technology has large capacity increase and is not beneficial to minimizing wastes.
Another class of resin processing techniques is High Integrity Container (HIC) direct fill and hot press techniques. High Integrity Containers (HIC) can achieve long-term safe containment of contents for up to 300 years or more. The waste resin is directly filled in the HIC, and can be directly disposed after the free water in the waste body is ensured to be less than 1 percent after multiple dehydration operations. The core of the technology is to realize the containment of the resin and the contained radionuclide by a packaging container, and the container has good performance of preventing the migration of the nuclide, so compared with the cement curing technology, the technology can ensure the long-term disposal safety. However, since the technology does not perform any treatment on the resin, the radioactive resin may leak out once the container is broken, so that additional measures are required to ensure the safety of the container in the transportation, temporary storage and disposal stages, and the volume reduction effect of the technology is general.
The hot pressing technology of resin is to dewater wet resin and send the resin into a drier. The dryer heats the waste resin to 160 ℃, residual moisture in the waste resin is carried by the vacuum pump and is gradually evaporated to dryness in the dryer. The dryer forms the resin into a high-density dried product. At the final stage of drying, special additives are added to enhance the bonding and tightness among the resins, and when the resins are in a hot state, the resins are barreled and covered, and then the resins are sent to a super compressor for overpressure treatment. The technology mainly aims at realizing the volume reduction of the resin, but in practice, overpressure is found to have a certain volume reduction effect on the resin, but the radioactivity ratio is improved, the resin property is not changed, and the long-term stability of the treated product after radiation degradation needs to be considered in a key way; on the other hand, this technique chooses ordinary metal bucket as packaging container for use, and there is great risk in the container safety.
In summary, the existing ion exchange resin treatment technology adopts a physical treatment method, and the technology has the following disadvantages: (1) the potential risk of poor stability in the long-term safe disposal process of the prepared waste body caused by the irradiation degradation of the resin can not be solved; (2) the bulk volume reduction of the resin cannot be achieved and the waste minimization principle is not satisfied. Therefore, in order to satisfy the principles of safe disposal and waste minimization, the advanced resin treatment technology should consider changing the macromolecular structure of the resin, converting the organic form of the resin into the inorganic form, and fundamentally realizing safe volume reduction.
The most productive radioactive waste in pressurized water reactor power plants, with the exception of resins, is technical waste, including: labor protection supplies, plastic cloth, wiping decontamination supplies and the like produced by daily maintenance. These wastes generally have low radioactivity levels, and are mostly made of organic materials such as fibers and plastics. The method for treating the wastes in all domestic pressurized water reactor power stations is compression, the essence of the compression technology is to eliminate free gaps in the wastes as much as possible and compact the wastes, but as time goes on, the materials are degraded and unstable risks are generated, even if a 2000 t-pressure super compressor is adopted, the compression volume reduction ratio can only reach 3-6 times, and the volume reduction effect is relatively limited.
Besides solid organic wastes such as waste resin and technical wastes, some radioactive liquid organic wastes such as waste oil and waste organic solvents in a pressurized water reactor power station can only be temporarily stored in a factory at present due to lack of proper treatment means. In order to treat the radioactive wastes generated from the above nuclear facilities, various practices are also being carried out in some countries and regions, wherein the most common and effective technology is a thermal process technology, which can be classified into pyrolysis, excess air incineration, controlled air incineration, plasma incineration, and the like according to the difference of the thermal process technology. However, the thermal treatment technique has some inherent drawbacks, mainly including: (1) the problem of combustion and explosion is that when the combustible gas in the incinerator suddenly increases instantly or the combustible gas composition is in the explosion range and meets open fire suddenly, the incinerator is subjected to instant positive pressure or combustion and explosion; (2) the problem of corrosion is prominent because substances containing halogen, sulfur, phosphorus and the like are incinerated, and the incinerator material is selected to be anticorrosive; (3) the secondary waste treatment problem, if the control is not good, the incineration process will produce dioxin, thereby causing secondary harm. (4) The problem of nuclide capture, the temperature of thermal treatment is often high, part of volatile nuclides can enter a tail gas treatment system, and the requirements on tail gas purification equipment are extremely strict; in addition, a part of the non-volatile species is difficult to form a stable structure, and may be dissolved in water.
In recent years, some prior art has been disclosed for the treatment of radioactive organic waste: "pyrolysis of organic waste" (CN99811428.6), this patent adopts a two-stage pyrolysis method to treat organic waste, the treatment object is limited to waste resin, this method has the problems of complicated flow, high energy consumption, single treatment object, etc. The 'treatment system of radioactive wastes and the treatment method containing the same' (CN201611201164.7) adopt the fixed bed gasification technology to treat the organic wastes, and have the problems of coking, catalyst failure and the like. In addition, there are some volume reduction treatment technologies for waste resin, but other types of organic waste such as technical waste, waste oil, and waste organic solvent cannot be treated.
In summary, there is a certain deficiency in the prior art for the treatment method and apparatus of radioactive waste resin, technical waste, waste oil and waste organic solvent, and there is a need to develop a new method for heat treatment of radioactive waste organic solvent, which can improve the treatment efficiency of waste resin, technical waste, waste oil and waste organic solvent, and realize the safe treatment, storage and volume reduction of radioactive waste.
Disclosure of Invention
The invention aims to provide a method and a system for treating radioactive organic waste by using a three-phase fluidized bed, which aim to overcome the defects of organic radioactive waste treatment modes in the prior art, treat various radioactive organic wastes, reduce the volume to a greater extent and mineralize and contain unstable pollution nuclides contained in the radioactive organic wastes.
The invention is realized by the following technical scheme:
a method for treating radioactive organic waste using a three-phase fluidized bed, comprising the steps of:
(a) filling a fluidized substrate and a catalyst in the three-phase fluidized bed;
(b) introducing radioactive organic waste into a three-phase fluidized bed, and simultaneously introducing a metal ion mineralizer, superheated steam, charcoal and air;
(c) the radioactive metal ions in the radioactive organic waste are subjected to mineralization containing reaction in the fluidized bed reaction section to generate a mineralization product, and nuclides are contained in the mineralization product;
(d) carrying out steam reforming reaction on organic components in the radioactive organic waste in a reaction section of the fluidized bed to produce combustible small molecule gas;
(e) the mineralized product is separated.
Based on the defects of the prior art in the organic radioactive waste treatment mode, the inventor thinks that in order to meet the principles of safe disposal and waste minimization, the advanced radioactive organic waste treatment technology considers changing the macromolecular structure of the waste and converting the organic form of the waste into the inorganic form, thereby fundamentally realizing safe volume reduction. Specifically, the method provided by the invention adopts a three-phase fluidized bed as a reactor, and the three-phase fluidized bed is a device capable of simultaneously realizing physical operation or chemical reaction on materials in three phases of gas phase, liquid phase and solid phase. After radioactive organic waste is introduced into a three-phase fluidized bed, the organic waste and a metal ion mineralizer are subjected to steam reforming and mineralization containing reaction to generate small-molecule combustible gas and mineralization products, nuclides are contained in the small-molecule combustible gas and the mineralization products, wherein a fluidized base material is used as a bed material, and a catalyst is used for improving the reaction efficiency of the steam reforming reaction. In the reaction process, high-temperature superheated steam is used as carrier gas, a prepared metal ion mineralization formula, a catalyst and the like and radioactive organic waste are subjected to reforming and mineralization reaction in a fluidized bed, finally tail gas is treated until the tail gas reaches the standard and is discharged, and nuclide is contained in a mineralization product to meet the condition of final barreling treatment. The final disposal container can be a high integrity container or a waste steel barrel. The invention is characterized in that the high-temperature atmosphere provided by superheated steam can create the condition similar to hydrothermal reaction formed by mineralized substances, and under the condition, metal oxide generated after organic waste is decomposed reacts with the added metal ion mineralizer to realize the mineralization containment of nuclides. Different metal ion mineralizers are selected according to different valence states of the nuclide, and the type of the metal ion mineralizer is specifically selected by the skilled person according to the actual situation (such as the kind of the nuclide to be treated).
The radioactive organic waste comprises one or more of solids, liquids, resins; the solid is technical waste, and the technical waste is put into a reaction section of a fluidized bed after being sorted, cut, crushed and pressed in sequence; the liquid is atomized and enters a fluidized bed reaction section under the action of compressed air; the resin is pumped into the fluidized bed reaction zone.
The organic components of the solid form waste organic matter undergo a steam reforming reaction under the action of superheated steam and a catalyst. The catalyst is Al adsorbed with fine Fe, Ni and other metal particles2O3And (3) a molecular sieve. The solid technical waste, the catalyst and the high-temperature steam passing through the gas distributor form a gas-solid phase fluidized state, and the surface of the technical waste and the high-temperature steam at 650-750 ℃ generate H under the action of the nickel-based or iron-based catalyst2，CO，CH4And a small amount of C2H6，C2H4，C2H2And the like. The radioactive metal ions in the technical waste react with the added mineralizing formula under the high-temperature atmosphere provided by the superheated steam to form spinel or feldspar-like mineralized substances. The reaction is endothermic, so air and charcoal can be added during the reaction to keep the reaction and ensure no excess of air and charcoal, and the fluidized bed in the form of electric heating can be used to control the internal temperature and keep the internal temperature constant.
Preferably, the small molecule combustible gas generated by decomposition enters a subsequent full oxidizer of the fluidized bed to be fully combusted with the added excessive fresh air and a small amount of supplemented natural gasGenerating H2O and CO2。
Preferably, the mineralized substance generated by the reaction is separated by a cyclone separator and a high-temperature filter which are connected with the rear end of the fluidized bed, and then the mineralized substance can be loaded into an HIC high integral container or a steel barrel for fixing, so that the receiving condition of a final disposal site is required to be met. The generated tail gas is treated by a tail gas treatment system to be qualified and then discharged after reaching the standard.
The invention adopts the three-phase fluidized bed to treat the solid organic waste and simultaneously treat the liquid organic waste. After passing through a liquid atomization distributor arranged at the fluidization section of the fluidized bed, the liquid organic waste forms small fog drops, is quickly gasified under the action of high-temperature steam, and then undergoes a reforming reaction with the high-temperature steam under the action of a catalyst in the fluidized bed.
In the steam reforming reaction process of the present application, the main reactions occurring in the fluidized bed include:
CaHbOcSm+H2O←→C+CH4+CO+H2+C2H6+C2H4+C2H2+SOx；
CaHbOcNm+H2O←→C+CH4+CO+H2+C2H6+C2H4+C2H2+NOx；
H2O+C←→H2+CO；
CO+H2O←→CO2+H2；
C+O2←→CO2；
2CO+O2←→2CO2；
2H2+O2←→2H2O。
the fluidizing base comprises Al2O3Or SiO2(ii) a The catalyst is a nickel-based or iron-based catalyst. The fluidized base material may be alumina balls, quartz sand balls, etc.
The metal ion mineralizer comprises one or more of kaolin, nepheline, sodium sulfate, sodium chloride, magnetite and alumina.
The monovalent cations form three-phase feldspar-like aluminosilicate mineralizers with the added kaolin mineralizer, which are present in cage and ring structures. Nepheline is the most basic aluminosilicate mineralized substance with the chemical formula Na2O-Al2O3-2SiO2. If sodium sulfate occupies the hollow positions of the cage structure, tetrahedrite is formed, of the formula 3Na2O-3Al2O3-6SiO2·Na2SO4. When sodium chloride occupies the hollow position of the cage structure, sodalite is formed, and the chemical formula of the sodalite is 3Na2O-3Al2O3-6SiO 22 NaCl. Depending on the composition of the waste, process additives such as magnetite may also be added to the reaction process to convert Cr to FeCr2O4Is fixed. The divalent or trivalent metal cations form spinel mineralizers with the added alumina mineralizer. The main components of spinel are metal, oxygen, and (if present) selenium and sulfur. The main factor controlling the spinel formation is the redox state of the metal, so the invention needs to control the internal reduction atmosphere of the reactor to fix the radioactive and harmful metals into the loss-resistant spinel structure, such as FeCr2O4、CoAl2O4And NiFe2O4And the like.
The main mineralization containment reactions that occur in the above process are as follows:
2NaOH+ Al2O3-2SiO2 ＝2NaAlSiO4+H2O
8NaOH+2Cl+ 3(Al2O3-2SiO2) ＝Na6Al6Si6O24(2NaCl)+3H2O+OH-
8NaOH+SO4+ 3(Al2O3-2SiO2) ＝Na6Al6Si6O24(Na2SO4)+3H2O+OH-
8NaOH+ReO4+ 3(Al2O3-2SiO2) ＝Na6Al6Si6O24(2NaReO4)+3H2O+OH-
6NaAlSiO4+ 2NaReO4 ＝Na6Al6Si6O24(2NaReO4)
2NaOH+ Al2O3-2SiO2 ＝2NaAlSiO4+H2O
8NaOH+2Cl+ 3(Al2O3-2SiO2) ＝Na6Al6Si6O24(2NaCl)+3H2O+OH-
8NaOH+SO4+ 3(Al2O3-2SiO2) ＝Na6Al6Si6O24(Na2SO4)+3H2O+OH-
8NaOH+ReO4+ 3(Al2O3-2SiO2) ＝Na6Al6Si6O24(2NaReO4)+3H2O+OH-
6NaAlSiO4+ 2NaReO4 ＝Na6Al6Si6O24(2NaReO4)
FeO+ Al2O3 ＝Fe(Al2O4)
NiO+ Al2O3 ＝Ni(Al2O4)
CoO+ Al2O3 ＝Co(Al2O4)
SrO+ Al2O3 ＝Sr(Al2O4)
the reaction temperature of the steam reforming reaction is 650-750 ℃, and the reaction pressure is-5 kPa to-20 kPa. Wherein-5 kPa and-20 kPa respectively represent the absolute pressure values of standard atmosphere minus 5kPa and standard atmosphere minus 20 kPa.
The technical waste is cut and crushed into particles with the diameter of 1.5 mm-6.0 mm; the liquid is atomized into droplets having a diameter of 100 to 200 μm.
In the method, the gas discharged from the three-phase fluidized bed contains H generated after reforming2，CO，CH4And a small amount of C2H6，C2H4，C2H2And the like, and a small amount of particle mineralization products are mixed. After the reaction of the three-phase fluidized bed, the particle size of the mineralized product is generally controlled to be 20-200 μm, wherein the mineralized product with the particle size of more than 50 μm can be separated by a built-in cyclone separator, and the mineralized product with the particle size of less than 50 μm can be separated by a high-temperature filter externally arranged on the three-phase fluidized bed. The radioactive organic waste is treated by the method, the volume reduction ratio of the waste is large, the generated tail gas is clean, the final product is stable, conditions are created for minimizing the final waste, and the technical guarantee is indirectly provided for normal operation of nuclear facilities.
The system for treating the radioactive organic waste by utilizing the three-phase fluidized bed comprises a three-phase fluidized bed, wherein the three-phase fluidized bed sequentially comprises a fluidized bed gas inlet section, a fluidized bed reaction section and a fluidized bed expansion section from bottom to top, and the fluidized bed gas inlet section is separated from the fluidized bed reaction section by a steam gas distributor; filling a fluidized base material and a catalyst in the fluidized bed reaction section;
the fluidized bed gas inlet section is communicated with a steam generator, and the steam generator is used for providing superheated steam into the fluidized bed gas inlet section;
the fluidized bed reaction section is communicated with a mineralizer storage tank and an organic waste introducing system, the mineralizer storage tank is used for providing a metal ion mineralizer into the fluidized bed reaction section, and the organic waste introducing system is used for introducing radioactive organic waste to be treated into the fluidized bed reaction section;
and the top exhaust end of the fluidized bed expansion section is connected with a filter.
The system is provided with a steam gas distributor in the three-phase fluidized bed for separating the air inlet section of the fluidized bed from the reaction section of the fluidized bed, and is used for uniformly distributing superheated steam which enters through a steam inlet and is generated by a steam generator and providing a stable fluidized gas source for the fluidized bed. Preferably, the steam generated by the steam generator is superheated by a steam superheater. The fluidized bed reaction section is communicated with a mineralizer storage tank and an organic waste introducing system. The top exhaust end of the fluidized bed expansion section is connected with a filter, and waste gas after the reaction is finished is filtered through the filter, so that the waste gas is conveniently discharged after reaching the standard.
The organic waste introducing system comprises a waste resin storage tank and a resin feeding port extending into the fluidized bed reaction section, and a resin feeding pump is arranged between the waste resin storage tank and the resin feeding port.
The organic waste introducing system comprises a technical waste sorting device, a technical waste cutting and crushing device and a technical waste compressing and packaging device which are sequentially arranged, and the compressed and packaged technical waste enters the fluidized bed reaction section through a technical waste feeder.
The organic waste lets in the system and includes organic waste liquid storage tank, stretches into the waste liquid atomization distributor in the fluidized bed reaction section, organic waste liquid material loading pump has between organic waste liquid storage tank and the waste liquid atomization distributor, the intercommunication has compressed air feeding device between organic waste liquid material loading pump and the waste liquid atomization distributor.
For the system, steam enters the tower body of the fluidized bed reaction section from the bottom of the tower body of the fluidized bed feeding section through a steam gas distribution plate. The steam gas distribution plate can ensure that steam is uniformly distributed in the fluidized bed tower body, provides stable airflow and is beneficial to normal reaction. Technical waste feeding system includes cutting unit, compression unit and conveying unit, cuts, compresses the technical waste after will sorting, makes it form the cuboid structure and is convenient for carry to inside the fluidized bed. The technical waste entering the fluidized bed is put into the fluidized bed tower body, is rapidly dispersed under the action of compressed air in the liquid atomizer, realizes fluidization under the action of steam flow, and generates steam reforming and mineralization containing reaction. The middle area in the tower body of the reaction section is provided with a liquid atomization distributor, which can realize the feeding and atomization of waste oil and waste organic solvent, accelerate the gasification process, and carry out reforming and mineralization reaction with steam under the action of catalyst in the reaction section. The waste resin is directly conveyed into the fluidized bed through a resin feeding pipe arranged in the lower area of the tower body of the reaction section, fluidization is realized in the reaction section under the action of steam, and steam reforming and mineralization accommodation reaction are carried out.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention relates to a method and a system for treating radioactive organic waste by utilizing a three-phase fluidized bed, which can realize gas-liquid-solid three-phase reaction by adopting the three-phase fluidized bed, can carry out steam reforming on radioactive solid and liquid organic waste and can carry out mineralization and containment on unstable pollution nuclide contained in the radioactive solid and liquid organic waste. By arranging the liquid atomization distributor and the solid waste feeding system, the processing object of steam reforming can be expanded to liquid organic waste and technical waste. By controlling the oxygen input amount and the steam flow, the temperature and the gas speed operation range of the fluidized bed can be controlled in a proper interval, and the liquid and solid radioactive organic wastes can be reformed, reduced in volume and mineralized and contained in the interval. The generated tail gas is clean, the final product is stable, conditions are created for minimizing the final waste, and the method has good application prospect in the field of radioactive organic waste treatment.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 is a schematic structural diagram of an embodiment of the present invention.
Reference numbers and corresponding part names in the drawings:
1-a fluidized bed gas inlet section, 2-a fluidized bed reaction section, 3-a fluidized bed expansion section, 4-a steam inlet, 5-a resin feed inlet, 6-a technical waste feeder, 7-an electric heater, 8-a cyclone separator, 9-a compressed air supply device, 10-a technical waste sorting device, 11-a technical waste cutting and crushing device, 12-a technical waste compression and packing device, 13-a waste resin storage tank, 14-a steam generator, 15-a steam gas distributor, 16-a packed technical waste, 17-a resin feeding pump, 18-a steam superheater, 19-a waste liquid atomization distributor, 20-an organic waste liquid storage tank, 21-an organic waste liquid feeding pump, 22-a mineralizer storage tank, 23-a feeding pump and 24-a filter.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1:
the embodiment comprises the following steps:
(a) filling a fluidized substrate and a catalyst in the three-phase fluidized bed;
(b) introducing radioactive organic waste into a three-phase fluidized bed, and simultaneously introducing a metal ion mineralizer, superheated steam, charcoal and air;
(c) the radioactive metal ions in the radioactive organic waste are subjected to mineralization containing reaction in the fluidized bed reaction section to generate a mineralization product, and nuclides are contained in the mineralization product;
(d) carrying out steam reforming reaction on organic components in the radioactive organic waste in a reaction section of the fluidized bed to produce combustible small molecule gas;
(e) the mineralized product is separated.
The radioactive organic waste comprises one or more of solids, liquids, resins; the solid is technical waste, and the technical waste is put into a reaction section of a fluidized bed after being sorted, cut, crushed and pressed in sequence; the liquid is atomized and enters a fluidized bed reaction section under the action of compressed air; the resin is pumped into the fluidized bed reaction zone.
The added mineralizer can be matched differently according to different valence states of the waste nuclide. The final product can form feldspar-like aluminosilicate mineralized matter with kaolin mineralizer, and the spinel mineralized matter with alumina mineralizer.
Filling a high-density fluidization base material including but not limited to bauxite balls and quartz sand balls in the three-phase fluidized bed; the particle size range of the fluidization base material is 1000-2000 microns.
Example 2:
the system device includes: a fluidized bed gas inlet section 1, a fluidized bed reaction section 2 and a fluidized bed expansion section 3. Wherein a steam inlet 4 is arranged in the gas inlet section 1 of the fluidized bed. A steam gas distributor 15 is arranged for separating the gas inlet section 1 and the reaction section 2 of the fluidized bed, and is used for uniformly distributing steam which enters through a steam inlet 4 and is generated by a steam generator 14 and superheated by a steam superheater 18 so as to provide a stable fluidizing gas source for the fluidized bed. The fluidized bed reaction section 3 is internally provided with a waste liquid atomization distributor 19, a technical waste feeder 6, a resin feed port 5 and an electric heater 7.
The waste resin is from a waste resin storage tank 13, is conveyed to a resin feed port 5 through a resin feeding pump 17, is fluidized in the fluidized bed reaction section 3 under the action of superheated steam, and is subjected to steam reforming reaction.
The technical wastes mainly comprise solid organic wastes such as clothes, gloves, masks, shoe covers and the like. The technical waste is firstly sorted by a technical waste sorting device 10 (which can be a glove box or other sorting devices) into parts (mainly metal parts) which are not allowed to enter a fluidized bed, and the rest parts are firstly cut and crushed by a technical waste cutting and crushing device 11 to be generally crushed into small particles (with the diameter of 1.5 mm-6.0 mm) meeting fluidization conditions. After cutting, the technical waste cut into fragments is pressed into packed technical waste 16 (generally 10cm multiplied by 6cm multiplied by 2cm, and the packed technical waste is packed into cuboid structures with different sizes according to fluidized beds with different processing capacities) with a cuboid structure by adopting a technical waste compression packing device 12, is conveyed into the fluidized bed reaction section 2 through a conveying mechanism, and is put into the fluidized bed reaction section through a technical waste feeder 6.
The liquid organic waste liquid stored in the organic waste liquid storage tank 20 enters the waste liquid atomizing distributor 19 through the organic waste liquid feeding pump 21, and forms mist droplets with the diameter of 100-200 μm in the atomizing distributor 19 under the action of the compressed air supplied by the compressed air supply device 9. The compressed air provided in the atomization distributor can act on the packing technical waste 16 at the same time, and under the combined action of the internal fluidization steam, the packing technical waste 16 can be rapidly dispersed into particles with the diameter of 1.5-6.0 mm, so that the condition of sufficient contact of the steam is met, and the fluidization reaction process is realized at the same time. The compressed air supply device 9 in the present embodiment is a compressed air storage tank.
The formation of mineralizers requires the addition of mineralizers. The mineralizer is stored in a mineralizer storage tank 22 and is delivered to the fluidized bed reaction section 2 through a mineralizer feeding pump 23. The solid and liquid organic wastes entering the reaction section 2 of the fluidized bed through the above process are fully mixed, heat-transferred, mass-transferred and reacted with the bed material (Al 2O3, or SiO2) which is added into the fluidized bed in advance. The solid waste particles are subjected to chemical reaction in a high-temperature environment, the particle size is gradually reduced, and the solid waste particles gradually rise to the expansion section 3 for further volume reduction under the action of airflow drag force. The liquid waste is quickly gasified in a high-temperature environment, and radioactive salt is quickly separated out. The residue after the volume reduction of the solid waste and the salt separated out after the gasification of the liquid waste are synthesized with a mineralizer in a proper reaction temperature range (650-750 ℃) to form a stable mineralized structure. The average residence time of the reactants is 600 s-1200 s. The treated solid residue (mainly mineralized products) is conveyed to the cyclone separator 8 in the middle of the expansion section 3 along with the air flow, and is captured by the cyclone separator 8 for circular reaction, so that the reaction efficiency is improved. The final product is captured by the rear filter 24 as a thermally treated final product. The temperature in the fluidized bed reaction section 2 is controlled by adjusting the solid feed ratio and the composition of the fluidized medium, and an electric heater 7 may be added to the outer wall of the fluidized bed reaction section 2 to maintain a specific reaction temperature in the bed.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (9)

1. Method for treating radioactive organic waste using a three-phase fluidized bed, characterized in that it comprises the following steps:
(a) filling a fluidized substrate and a catalyst in the three-phase fluidized bed;
(b) introducing radioactive organic waste into a three-phase fluidized bed, and simultaneously introducing a metal ion mineralizer, superheated steam, charcoal and air;
(c) the radioactive metal ions in the radioactive organic waste are subjected to mineralization containing reaction in the fluidized bed reaction section to generate a mineralization product, and nuclides are contained in the mineralization product;
(d) carrying out steam reforming reaction on organic components in the radioactive organic waste in a reaction section of the fluidized bed to produce combustible small molecule gas;
(e) separating the mineralized product;
the radioactive organic waste comprises one or more of technical waste, organic waste liquid and resin;
the technical waste is put into a reaction section of a fluidized bed after being sorted, cut, crushed and pressed in sequence; the organic waste liquid is atomized and enters a fluidized bed reaction section under the action of compressed air; feeding the resin into a fluidized bed reaction section by a resin feed pump;
the reaction process takes high-temperature superheated steam as carrier gas;
the three-phase fluidized bed is a vertical container with a material inlet at the lower part and a material outlet at the upper part, and is provided with a superheated steam inlet, a resin inlet, a technical waste inlet and an organic waste liquid inlet from bottom to top in sequence in the vertical direction;
during the steam reforming reaction, the main reactions taking place in the fluidized bed include:
CaHbOcSm+ H2O ←→ C + CH4 + CO + H2+ C2H6 + C2H4 + C2H2+SOx，
CaHbOcNm+ H2O ←→ C + CH4 + CO + H2+ C2H6 + C2H4 + C2H2+NOx；
the high-temperature atmosphere provided by the superheated steam can create conditions similar to hydrothermal reaction formed by mineralized substances, and under the conditions, metal oxides generated after the decomposition of the organic waste react with the added metal ion mineralizer to realize mineralization accommodation of nuclides;
after the mineralized substance generated by the reaction is separated by a cyclone separator and a high-temperature filter which are connected with the rear end of the fluidized bed, the mineralized substance can be loaded into an HIC high integral container or a steel barrel for fixation, and the acceptance condition of a final disposal site is required to be met.
2. The method of claim 1, wherein the fluidizing base comprises Al2O3Or SiO2(ii) a The catalyst is a nickel-based or iron-based catalyst.
3. The method of claim 1, wherein the metal ion mineralizer comprises one or more of kaolin, nepheline, sodium sulfate, sodium chloride, magnetite, and alumina.
4. The method of claim 1, wherein the steam reforming reaction has a reaction temperature of 650 ℃ to 750 ℃ and a reaction pressure of-5 kPa to-20 kPa.
5. The method for treating radioactive organic waste using a three-phase fluidized bed according to claim 2, wherein the technical waste is cut and crushed into particles having a diameter of 1.5mm to 6.0 mm; the organic waste liquid is atomized into fog drops with the diameter of 100-200 mu m.
6. The system for treating the radioactive organic waste by utilizing the three-phase fluidized bed comprises a three-phase fluidized bed, wherein the three-phase fluidized bed sequentially comprises a fluidized bed gas inlet section (1), a fluidized bed reaction section (2) and a fluidized bed expansion section (3) from bottom to top, and is characterized in that the fluidized bed gas inlet section (1) and the fluidized bed reaction section (2) are separated by a steam gas distributor (15); a fluidized base material and a catalyst are filled in the fluidized bed reaction section (2);
the fluidized bed gas inlet section (1) is communicated with a steam generator (14), and the steam generator (14) is used for providing superheated steam into the fluidized bed gas inlet section (1);
the fluidized bed reaction section (2) is communicated with a mineralizer storage tank (22) and an organic waste introducing system, the mineralizer storage tank (22) is used for providing a metal ion mineralizer into the fluidized bed reaction section (2), and the organic waste introducing system is used for introducing radioactive organic waste to be treated into the fluidized bed reaction section (2);
the top exhaust end of the fluidized bed expanding section (3) is connected with a filter (24);
the three-phase fluidized bed is a vertical container with a material inlet at the lower part and a material outlet at the upper part, and is provided with a superheated steam inlet, a resin inlet, a technical waste inlet and an organic waste liquid inlet from bottom to top in sequence in the vertical direction;
during the steam reforming reaction, the main reactions taking place in the fluidized bed include:
CaHbOcSm+ H2O ←→ C + CH4 + CO + H2+ C2H6 + C2H4 + C2H2+SOx，
CaHbOcNm+ H2O ←→ C + CH4 + CO + H2+ C2H6 + C2H4 + C2H2+NOx；
the high-temperature atmosphere provided by the superheated steam can create conditions similar to hydrothermal reaction formed by mineralized substances, and under the conditions, metal oxides generated after the decomposition of the organic waste react with the added metal ion mineralizer to realize mineralization accommodation of nuclides;
after the mineralized substance generated by the reaction is separated by a cyclone separator and a high-temperature filter which are connected with the rear end of the fluidized bed, the mineralized substance can be loaded into an HIC high integral container or a steel barrel for fixation, and the acceptance condition of a final disposal site is required to be met.
7. The system for treating radioactive organic waste using a three-phase fluidized bed according to claim 6, wherein the organic waste introducing system comprises a waste resin storage tank (13), a resin feed port (5) extending into the fluidized bed reaction section (2), and a resin feeding pump (17) is provided between the waste resin storage tank (13) and the resin feed port (5).
8. The system for treating radioactive organic waste using a three-phase fluidized bed according to claim 6, wherein the organic waste introducing system comprises a technical waste sorting device (10), a technical waste cutting and crushing device (11), and a technical waste compressing and packing device (12) which are sequentially arranged, and the compressed and packed technical waste enters the fluidized bed reaction section (2) through the technical waste feeder (6).
9. The system for treating radioactive organic waste by using a three-phase fluidized bed according to claim 6, wherein the organic waste introducing system comprises an organic waste liquid storage tank (20) and a waste liquid atomizing distributor (19) extending into the fluidized bed reaction section (2), an organic waste liquid feeding pump (21) is arranged between the organic waste liquid storage tank (20) and the waste liquid atomizing distributor (19), and a compressed air supply device (9) is communicated between the organic waste liquid feeding pump (21) and the waste liquid atomizing distributor (19).
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