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INVENTION
Russian Federation Patent RU2279726
METHOD FOR PROCESSING ORGANIC RADIOACTIVE WASTE
Name of the inventor: Terentyev Alexander (RU); Aleksandrov Aleksandr Borisovich (RU); Kovalev Igor V. (RU); Alexander Leonidovich Hlytin
The name of the patentee: Open Joint Stock Company "Novosibirsk Chemical Concentrates Plant"
Address for correspondence: 630110, Novosibirsk, st. B. Khmelnitsky, 94, JSC Novosibirsk Chemical Concentrates Plant, Patent Information Department
Starting date of the patent: 2004.07.15
The invention relates to the field of radioactive waste. The inventive method for the processing of organic radioactive waste, including waste incineration, followed by extraction of the radionuclides and waste gas purification. Feed waste is carried out discretely through pnevmoforsunku on top of the bottom of reactor warmed. Evaporated waste is burned in the reactor using an ignition source. Hot gaseous products of combustion due to expansion of the air supply and the reactor cooled in the upper part of the reactor and then bubbled trapped with sodium hydroxide solution, from purifying phosphoric anhydride, carbon oxides and nitrogen. Next purified gas from aerosols of sodium hydroxide to the aerosol filter, and then heated to oxidize at 250-300 ° C the copper-containing catalyst, solid waste is removed from the walls of the lower part of the reactor for subsequent recovery of radionuclides. The advantages of the invention are to increase the depth of purification and simplification of the process.
DESCRIPTION OF THE INVENTION
This invention relates to methods of processing radioactive waste organic providing clearance to the organic part of the waste substances and environmentally safe transfer of radionuclides, particularly uranium, into a compact form suitable for subsequent extraction of radionuclides.
A method of processing radioactive waste by flaring and then fired a multistage neutralization of liquid and gaseous wastes, described in Sec. 2.5 "Shaft furnaces" Bernadiner MN Shurigin AP / In the book "Fire recycling and disposal of industrial waste", Chemistry 1990
The method consists in burning liquid and gaseous wastes in the furnace GIAP shaft type, which is a vertical cylindrical chamber equipped at the head of burners for liquid or gaseous fuels. The disadvantages of this method are: the complexity of the hardware design, the lack of completeness of combustion, the difficulty of extracting radionuclides.
The closest to the technological essence and achieved result - a prototype - a method for the processing of organic radioactive waste in the Russian Federation patent №2130209, IPC 6 G 21 F 9/32, 9/14, F 23 G 7/00, 5/30, 1999
The method involves spraying a liquid radioactive waste nozzle above the fluidized bed of granular catalyst at a temperature of 600-700 ° C, cooling the hot waste gases to 250-300 ° C by a heat exchanger located in the reactor waste gas cleaning from solids coarse fraction, in during which the temperature is lowered to 200-230 ° C, from the flue gas cleaning particulates and toxic components sulfur oxide (IV) and phosphorus pentoxide in a jet scrubber cleaning gases from solid aerosols and acidic gases in the absorber, condenser, additional cleaning gases from solid submicronic The filter particles.
Disadvantages of the prototype are: complex hardware design, the need to purify gases from coarse particles and medium size, the poisoning of the catalyst, the difficulty in recovering and returning the production of radionuclides, particularly uranium.
OBJECT OF THE INVENTION: simplify hardware design, increasing combustion efficiency and depth of the waste gas purification and simplification of extraction of radionuclides from the resulting solid waste.
The problem is solved thanks to a method for processing organic radioactive waste by incineration followed by extraction of radionuclides and purification of exhaust gases, according to claims feeding waste carried discretely through pnevmoforsunku on top warmed the bottom of the reactor, vaporized waste is burned in a reactor with a source of ignition, the hot gases combustion products due to the expansion and feeding air to the reactor cooled in the upper part of the reactor and then bubbled trapped with sodium hydroxide solution, purged of phosphoric anhydride, carbon oxides and nitrogen, more gas is purified of sodium hydroxide aerosol aerosol filter and is then fed to heated up 250-300 ° C Cu-containing catalyst, solid waste is removed from the walls of the lower part of the reactor for subsequent recovery of radionuclides.
Said combination of features is a new unknown in the art since the evaporation is difficult flammable liquid organic radioactive waste and its spark ignition gas phase practically allows to burn them in a short time resulting high temperature and high excess oxygen, thus fully concentrate the uranium in the combustion chamber and in the absorption solution, from the exhaust gases to neutralize toxic components to concentrations below the MPE (maximum permissible emissions) to receive solid waste combustor after stripping in small amounts and which are suitable for the extraction of uranium to return to production.
Spraying pnevmoforsunkoy applied due to the more simple way to transfer the liquid spray and mixing organic waste with oxygen to increase combustion efficiency. Vaporization of the liquid waste can easily ignite the organic waste compared to hard-ignition of combustible liquid aerosols. Flaming method of all thermal methods is simple execution and higher efficiency of sanitary disposal of combustible liquid waste. Bubbling through the sodium hydroxide solution was chosen as a cheap and easy in hardware design method of wet gas purification. Thermal catalytic oxidation to copper-containing catalyst at a temperature of 250-300 ° C necessary for neutralization of exhaust gases from a high concentration of carbon oxide (II), formed during this combustion process and allows 99,8-99,9% of the oxidized gas.
The method is carried out on the apparatus shown in FIG.
The plant consists of a reactor burning organic radioactive waste (1), comprising: the combustion chamber (2), the expansion chamber (3), pnevmoforsunki (4) the reactor bottom combustion (5), a compressed air supply tube (6) and outlet exhaust gases (7) elektrosvechi (8) and the heating element (9); pnevmozatvora (10) traps sodium hydroxide solution (11) and the aerosol filter (12) and the thermal catalytic oxidation reactor (13) with a copper-containing catalyst fixed bed (14).
A method of processing radioactive organic wastes is carried out as follows: organic liquid radioactive waste discretely sprayed under pressure in the reactor (1) through pnevmoforsunku (4) heated up to the heating element (9), the bottom of the reactor (5). Liquid wastes are vaporized. Couples ignited using an ignition source (8), operating in a constantly enabled network operation, while there is a short-term high temperature in the reactor (1) through a tube (6) on top of constantly supplied with air, and after the ignition is carried out a purge air from below, increasing the air flow rate pnevmoforsunke to (4), which allows the reactor to saturate the oxygen needed for combustion is able to compensate for the vacuum that occurs after an outbreak, and to cool the exhaust gases. The exhaust gases from the combustion chamber (2) enter into the expansion chamber of the reactor (3), which reduce their speed and temperature, then the exhaust gases are directed through the nozzle (7) in pnevmozatvor (10), which prevents a possible ingress of sodium hydroxide solution to the reactor (1) due to discharge occurring after the flash, and then fall into the trap (11) and is bubbled through a solution of sodium hydroxide. During the passage of exhaust gases through the sodium hydroxide solution is removed from the gas phase phosphorus pentoxide, significantly reduced the concentration of carbon dioxide and nitrogen oxides. Further, the waste gases are treated in the aerosol filter (12) of sodium hydroxide and aerosols enter the catalytic thermal oxidation reactor (13) with a copper-containing catalyst fixed bed (14) heated to a temperature of 250-300 ° C, wherein the carbon monoxide is oxidized (II ) and its content in the exhaust gas is lower than the MPE, which is safe for the environment. Solid waste is discharged from the combustion chamber and directed to the extraction of radionuclides.
Example of the method.
Liquid organic radioactive waste from the uranium concentration of 0.3 g / l at a pressure of about 0.8-1 atm discretely raspylyalyayut through pnevmoforsunku to warm up to 150-200 ° C bottom of the combustion chamber, is heated and vaporized. Pairs ignited via spark. The exhaust gases after the combustion chamber enter into the expansion chamber combustion reactor where its pressure is reduced to 0.3-0.5 atm and the temperature to 40-90 ° C. For oxygen saturation of the combustion chamber and the subsequent possibility of initiating ignition reaction in the expansion chamber, compressed air is additionally fed. Subsequent reaction of ignition and burning and further carbon accumulating on the walls of the combustion chamber, reducing the amount of soot formed and increasing the concentration of uranium in solid waste; Further exhaust gases passing pnevmozatvor, and are trapped therein bubbled through the sodium hydroxide solution with a concentration of 50-120 g / l. During the passage of exhaust gases through the sodium hydroxide solution from the gas phase is almost completely removed phosphoric anhydride, significantly reduces the concentration of carbon dioxide and nitrogen oxides. Next, the exhaust gases are cleaned from aerosols of sodium hydroxide to the aerosol filter is passed to the catalytic thermal oxidation reactor, where the preheating of the gases and the subsequent oxidation of carbon monoxide (II). While passing the gases through a fixed bed of copper-containing catalyst, heated to a temperature of 250-300 ° C, gases are cleaned to concentrations below the concentration limit of the working area - 20 mg / m 3.
The concentration of uranium in the solid residues is 6,69-16,27% and waste sodium hydroxide solutions 0,9-18 mg / l depending on the volume of the solution and the volume of exhaust gas passing sparging. Carbon content in the uranium-containing carbon black is about 17%.
The process parameters and test results are shown in Table 1.
Thus, the proposed method makes it possible to simplify the hardware design, reducing the quantity of solid waste, increase the burning of organic liquid radioactive waste, reduce flue gas temperature, neutralize the waste gases of toxic components to safe concentrations of uranium concentrate and get fit to return to production.
CLAIM
Method for processing organic radioactive waste by incineration followed by extraction of radionuclides and purification of flue gases, wherein the flow of waste is carried out discretely through pnevmoforsunku on top warmed the bottom of the reactor, vaporized waste is burned in the reactor with an ignition source, the hot gaseous products of combustion due to expansion and flow cooled air into the reactor in the upper part of the reactor and then bubbled trapped with sodium hydroxide solution, from purifying phosphoric anhydride, carbon oxides and nitrogen gases further purified by aerosols of sodium hydroxide to the aerosol filter, and then heated to oxidize at 250-300 ° C the copper catalyst solid waste is removed from the walls of the lower part of the reactor for subsequent recovery of radionuclides.
print version
Publication date 20.02.2007gg
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