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    • 专利摘要:
    "In-situ" gasification process by means of pyrolysis and catalytic photo-oxidation of radioactive waste of low activity (RBBA) from the nuclear industry, which includes: the fragmentation and crushing of radioactive waste; the gasification of the waste crushed by a pyrolysis process with the production of a synthesis gas (syngas); the recovery of the oils present in the gaseous effluent through the cooling and subsequent washing of the syngas and the concentration of the oils recovered by evaporation in vacuum; the photo-oxidation of the organic compounds present in the syngas by means of a photo-oxidation process: the conversion of H2CH4and CO present in the gaseous effluent in CO2and H2O by a catalytic oxidation process; and the purification of the gas stream by filtration with activated carbon. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2684540A1
    申请号:ES201700305
    申请日:2017-03-29
    公开日:2018-10-03
    发明作者:Sergio TUSET MÉNDEZ；Daniel VILDOZO CORTEZ
    申请人:CONDORCHEM ENVITECH S L；CONDORCHEM ENVITECH SL；
    IPC主号:
    专利说明:

    DESCRIPTION

    In-situ gasification procedure by pyrolysis and catalytic photo-oxidation of low-level radioactive waste (RBBA) from the nuclear industry.
     5
    Object of the invention

    The object of the present invention is a process of gasification of low-level radioactive waste to obtain a reduction in volume and weight. This process may reduce these types of waste (RBBA) by more than 80% by volume and more than 60% by weight. This process meets the technical requirements to be carried out on-site, that is, at the nuclear power plants themselves, radioactive material handling centers or nuclear fuel factories. Thus avoiding transport and management costs to radioactive waste storage centers.
     fifteen
    Field of application of the invention

    This invention is applicable for the treatment of low-level radioactive waste, essentially including waste related to handling and maintenance operations, such as work clothing, safety shoes, used filters, disposable products such as gloves, masks, fabrics , rags, wooden pallets, plastics and packaging, etc., that is, all material that is generally combustible and / or of organic origin from handling and processes in the nuclear industry and radioactive components.
     25
    State of the art

    One of the most delicate aspects of nuclear activity is the generation of radioactive waste from this type of industry.
     30
    In Spain, for example, fundamentally low and medium activity waste is generated (approximately 95%), these come from nuclear activity, but also many are generated in hospitals, research centers or certain industrial activities. Its management begins in the center itself with its conditioning for the transfer to specialized storage and disposal centers. For the adequate confinement of these radioactive waste, natural and engineering barriers are interposed, so that the contaminated materials are completely isolated for as long as they need for their radioactive activity to disappear.

    Another process used is the transfer of these radioactive waste to incineration plants. The Incineration is a combustion process in the presence of oxygen, in which toxic gases (NOx, SOx, Dioxins, Furans) can be generated which must be treated with a high maintenance cost and without guarantee of not exceeding the limits of emissions

    To reduce the amount of waste for temporary storage and minimize disposal costs, all countries apply or plan to apply measures to reduce the volume of waste generated, when possible. The volume reduction is particularly interesting for low activity wastes that are generally of large volume but of low radioactivity.
     fifty
    One of the essential objectives of this new process is to reduce as much as possible the volumes of waste to be stored or evacuated, that is, to concentrate as much as possible the radioactivity contained in the waste.
    Experience has shown that between 50% and 80% of solid radioactive waste produced in nuclear power plants and nuclear fuel production factories can be classified as combustible waste.

    This invention presents a substantial improvement from several points of view with respect to compaction / management and incineration. A very high volume reduction can be achieved up to 80% and up to 60% by mass. The final product is an inert homogeneous ash that can be packed in containers for evacuation, and a gaseous stream that is purified for subsequent emission into the atmosphere, complying with the corresponding environmental standards. 10

    The reason for this patent is not to claim the processes of pyrolysis, photo-oxidation and catalytic oxidation that are in the public domain, but focuses on the use of these three technologies together, optimizing them for application to reduction in volume, and in Weight of low level radioactive waste. fifteen

    The applicant of the present invention is unaware of the existence of antecedents that allow the reduction of this type of reactive waste by means of these three technologies together.

    The rising cost of radioactive waste disposal provides an incentive to adopt procedures aimed at minimizing waste quantities and developing new technologies to minimize volumes in the conditioning of this type of waste.

    Description of the invention

    The process begins, with a conditioning of the mixed solid waste, prior to gasification, cutting, fragmentation and crushing are used to reduce the physical size of the various waste elements. Paper, plastics, clothing, cardboard, wood, etc. They fragment into small pieces smaller than 10 mm. 30

    These already crushed parts are introduced into an optimized pyrolysis reactor in which thermal energy is applied, either by electrical systems (electrical resistors, induction, etc.) or with gas combustion (natural gas, butane, propane, syngas, etc. .), to reach the ideal temperature and nitrogen to inert the process. This process will be carried out at 35 temperatures between 500 - 700 ° C and in the absence of O2. The bonds of the molecules of the residues present in the pyrolytic chamber will break, forming atoms and compounds of short carbon chains.

    The products of this process are a synthesis gas (syngas) and a solid fraction rich in 40 carbon (inert ash) that will also contain the radioactive particles and that non-gasifiable solid fraction (metals, inerts, etc.).

    The syngas will consist mainly of hydrogen (H2) gases, in a proportion of 10% - 40%, depending on the total composition. To a lesser extent, we will also obtain: methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), pentane (C5H12), ammonia (NH3), oxygen (O2), monoxide and carbon dioxide (CO , CO2), in addition to light oils (mixtures of benzene (C6H6), toluene (C7H8), xylene (C8H10) and others).

    The composition of the syngas produced by the pyrolysis of the solid waste will depend on the 50 process conditions such as the operating temperature, the heating rate and mainly on the composition of the feed waste.

    The ash formed is removed from the process for its respective storage and management.
    The produced syngas is sent to a fast gas cooler or quench where it will be cooled to a temperature between 20 ° C and 45 ° C and subsequently washed with water by means of a scrubber, this with the aim of eliminating bituminous compounds present in the gas stream. The scrubber wash water purge will be treated by a vacuum evaporator, to minimize the volume of this residue that can be mixed with the ashes and managed externally.

    To avoid risks in the purification of syngas, due to its high hydrogen content, it is diluted with ambient air in a proportion of 1/100 to 1/400, this in order to reduce the total concentration of H2 (<1%) , and is directed to a purification process that uses two oxidation technologies, one in the gas phase (photo-oxidation) and the other in the catalytic phase (oxidation-catalytic).

    In gas photo-oxidation, volatile organic compounds produced such as CH4, C2H6, C3H8, etc. they are reduced thanks to the formation of very oxidizing free radicals such as 15 OH- and O-. These radicals are capable of oxidizing most of the organic compounds, resulting in several by-products and other oxidizing radicals, thus causing a chain reaction until complete oxidation of the contaminant. The oxidizing radicals will be formed in the presence of air and moisture existing in the gas flow and UV irradiation from quartz lamps (185 nm. And 254 nm.) Present in the photo-oxidation reactor.

    Once the gas has been purified from organic and odorizing compounds, it is directed to a second process, which is that of catalytic oxidation. At a temperature of 300 ° C to 400 ° C and thanks to the presence of a catalyst (PdAl2O3), the remaining H2, CH4 and CO from the gasification of 25 radioactive waste are converted into CO2 and H2O. This process is exothermic, therefore, once the reaction temperature is reached it will be a self-thermal process, thus avoiding the consumption of external energy.

    The gas stream thus treated will go through a final stage, which consists of a battery of 30 filtration of the volatile gaseous radio-nuclides that may still be present. This battery of activated carbon-based filters allows this type of compound to be retained, allowing its radioactive decay to occur.

    Description of the figures 35

    To complement the description that is being made and in order to facilitate the understanding of the characteristics of the invention, a set of figures is attached to the present specification in which, for illustrative and non-limiting purposes, the following has been represented: 40

    - Figure 1 shows a diagram with the different phases or stages of the gasification process of low-level radioactive waste.

    Preferred Embodiment of the Invention

    In Figure 1 the phases of the procedure described above have been schematically represented, including:

    a) The cutting, fragmentation and crushing of low-level radioactive waste 50 until a mixture of radioactive waste of a size equal to or less than 10 mm is reached.

    b) The gasification of radioactive waste through a pyrolysis process at a temperature between 500 ° C and 700 ° C, with the production of a synthesis gas (syngas).

    c) The recovery of the oils present in the gaseous effluent, by rapid cooling 5 to a temperature of 20 ° C to 45 ° C and subsequent washing of the syngas produced in the pyrolysis in order to eliminate the bituminous hydrocarbons present in the stream soda after cooling; and the concentration of the oils recovered by evaporation under vacuum.
     10
    d) The photo-oxidation of the organic compounds and odorants present in the syngas by means of a photo-oxidation process in a reactor with ultraviolet irradiation thanks to the presence of the radicals formed in said ultra-violet reactor.

    e) The conversion of 100% of H2, CH4 and CO present in the gaseous effluent into CO2 and 15 H2O through a catalytic oxidation process.

    f) Purification of the gas gaseous by filtration with activated carbon, before being sent to the atmosphere, avoiding any emission of volatile radioactive compounds. twenty

    The main component in the process of gasification of radioactive waste by means of pyrolysis, is a pyrolytic reactor consisting of a chamber with external heating, hermetic and coated with a thermally insulating envelope.
     25
    This chamber rotates slowly and reaches a temperature between the mentioned 500 ° C and 700 ° C; counting said camera with a small inclination in the direction of feeding towards the discharge.

    In the catalytic oxidation process a catalyst is used, for example PdAI2O3, which has a high selectivity for the removal of H2.

    Once the nature of the invention has been sufficiently described, it is noted that the changes deemed appropriate may be introduced therein, provided that this does not imply an alteration of the essential characteristics of the invention claimed then.
    权利要求:
    Claims (1)
    [1]

    1. "In-situ" gasification process by pyrolysis and catalytic photo-oxidation of low-level radioactive waste (RBBA) from the nuclear industry, characterized in that it comprises:
    a) The cutting, fragmentation and crushing of low-level radioactive waste until a mixture of radioactive waste of a size equal to or less than 10 mm is reached.
     10
    b) The gasification of radioactive waste through a pyrolysis process at a temperature between 500 ° C and 700 ° C, with the production of a synthesis gas (syngas).
    c) The recovery of the oils present in the gaseous effluent, by cooling to a temperature of 20 ° C to 45 ° C and subsequent washing of the syngas produced in the pyrolysis; and the concentration of the oils recovered by evaporation under vacuum.
    d) The photo-oxidation of the organic compounds and odorants present in the syngas by a photo-oxidation process in a reactor with ultraviolet irradiation thanks to the presence of the radicals formed in said ultra-violet reactor.
    e) The conversion of 100% of H2 CH4 and CO present in the gaseous effluent into CO2 and H2O through a catalytic oxidation process.
     25
    f) The purification of the gas stream by filtration with activated carbon, before being sent to the atmosphere, avoiding any emission of volatile radioactive compounds.
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    同族专利:
    公开号 | 公开日
    ES2684540B1|2019-07-10|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DE3224054A1|1982-06-28|1983-12-29|Kiener Pyrolyse Gesellschaft für thermische Abfallverwertung mbH, 7000 Stuttgart|Process and apparatus for volume reduction of organic waste of low radioactivity|
    ES2008214A6|1987-09-14|1989-07-16|Tecnicas Especiales De Reducci|Mobile incinerator system for low level radioactive solid waste.|
    FR2766954A1|1997-07-30|1999-02-05|Hankuk Fiber Co Ltd|Low level radioactive media or waste treatment apparatus|
    KR101622336B1|2015-11-18|2016-05-18|예평이앤씨|Volume compaction and carbonization system for low-level radioactive waste|
    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
    ES201700305A|ES2684540B1|2017-03-29|2017-03-29|"In situ" gasification procedure by pyrolysis and catalytic photo-oxidation of low-level radioactive wastefrom the nuclear industry|ES201700305A| ES2684540B1|2017-03-29|2017-03-29|"In situ" gasification procedure by pyrolysis and catalytic photo-oxidation of low-level radioactive wastefrom the nuclear industry|
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