RU145990U1 - INSTALLATION FOR DISPOSAL OF WASTE CONTAINING URANIUM COMPOUNDS - Google Patents

Abstract

Installation for the disposal of waste, including uranium compounds, containing a thermal decomposition chamber with external heating, a burner, a catalytic afterburner, a heat exchanger, a dust cleaning system, and a smoke exhauster, characterized in that the entrance to the thermal decomposition chamber is equipped with a discrete loading gateway device, the chamber has an internal volume of thermal decomposition is equipped with a continuous moving device; the exit from the thermal decomposition chamber is equipped with a coxo sluice discharge device of the residual residue and the vapor-gas mixture removal device connected to the burner device, the output of which is connected to the entrance to the catalytic afterburner, the output of which is connected to the entrance to the heat exchanger, and all the geometrical dimensions of the units are made in accordance with nuclear safety requirements, eliminating the possibility of critical accumulation masses of uranium compounds during the process. 2. Installation according to claim 1, characterized in that the internal volumes of all the units of the installation do not exceed 4 liters, and their transverse dimensions do not exceed 110 mm.

Description

The claimed utility model relates to the field of disposal of organo-waste.

A known installation for the processing of radioactive waste, providing for the burning of waste in a shaft furnace. [Markelov N.I. and other installation for the processing of radioactive waste. Patent model-22837, 07/09/2002].

The disadvantage of this installation is that since the waste is burned due to the operation of the burner with excess air and the supply of flue gases to the material layer, the entire process takes place under excessive pressure and there is the possibility of uncontrolled release of radioactive materials into the atmosphere.

Another disadvantage of the installation is the lack of devices that prevent the possibility of radioactive components entering the atmosphere during loading and unloading operations, as well as the mismatch between the design of individual components and nuclear safety requirements.

Known installation for the thermal destruction of solid waste contaminated with radioactive components [Dvoskin G.I, Starostin AD et al. RF Patent No. 81292 of 03/10/2009] containing a thermal decomposition chamber equipped with a device for loading waste, a means for unloading a coke ash residue, a grate for burning coke residue, a channel for discharging gaseous products of thermal decomposition, a vertical cyclone furnace with a burner device, catalytic afterburner, heat exchanger, gas purification system and smoke exhaust.

The disadvantage of the installation is the pulsation of the operational parameters of the process due to the uneven cyclical decomposition of the waste in the thermal decomposition chamber and, accordingly, the cyclical intake and combustion of gaseous products in the burner of the cyclone furnace with uneven, short-term (volley) evolution of a large amount of heat, which, in its First of all, it requires the presence of large surfaces of heat-exchange equipment, which is used inefficiently, since it works in non-optimal pulsating m mode. This process flow is explained by the following:

The subject of disposal is, as a rule, a mixture of wastes contaminated with uranium oxides with the following composition: rubber products –50%, rags –35%, plastics –10%, other –5%. The average calorific value of the mixture is approximately 20-22 MJ / kg. Usually, in the process of pyrolysis of organics, the main time is heating the material to the temperature of the beginning of its thermal decomposition, and the process of pyrolysis occurs very quickly. When a portion of the material is loaded into the thermal decomposition chamber once, its decomposition cycle is divided into three time periods: heating — about 35% of the total cycle time, the main pyrolysis process — 20%, and residual processes — 45%. Thus, the main load on the equipment, including heat transfer, accounts for only 20% of the total cycle time. The rest of the time, energy resources, calculated to the maximum for supplying the amount of air necessary for burning a gas-vapor mixture and a cooling agent (air) into a heat exchanger, are wasted. This is especially true for the pyrolysis of high-calorie material, when there is a rapid evolution of a vapor-gas mixture and, accordingly, a large amount of heat for several minutes. To remove a large amount of heat in a limited time, the heat exchange equipment must have a large surface, which, based on nuclear safety requirements, limiting the geometric dimensions of the equipment (transverse diameters of not more than 110 mm), must be assembled from a large number of small units, which is not technologically and uneconomical. It is impossible to equalize the pulsation of the process by adding a new portion of material to the reaction device because of the danger of a critical mass of uranium 235 accumulating in it (more than 2.5 kg).

Another disadvantage of the installation is that when burning coke residue on the grate, ash accumulation can also lead to the formation of a critical mass of uranium 235, since the bulk of the radioactive components remain in the ash.

Another disadvantage of the installation is that when loading another portion of the waste and unloading the coke-ash residue, air from the environment may enter the thermal decomposition chamber and vice versa, the pyrolysis products into the environment.

The technical result, which this utility model is aimed at, is to reduce the metal consumption of heat exchange equipment and save energy by ensuring the uniformity of the process of thermal decomposition; ensuring the impossibility of air entering the thermal decomposition chamber, and thermal decomposition products into the environment due to the blocking of the waste feed into the thermal decomposition chamber; and ensuring the impossibility of accumulating a critical mass of 235 uranium compounds in individual units of the facility due to their implementation in accordance with nuclear safety requirements.

The task is achieved by the fact that the entrance to the thermal decomposition chamber of the installation is equipped with a discrete loading lock device, the internal volume of the thermal decomposition chamber is equipped with a continuous moving device, the exit from the thermal decomposition chamber is equipped with a discrete discharge coking residue discharge device and a vapor-gas mixture removal device connected to burner device, the output of which is connected to the entrance to the catalytic afterburner It is connected to the inlet to the heat exchanger, and the internal volumes and geometrical dimensions of the installation units do not exceed 4 liters and 110 mm, respectively.

The essence of the proposed technical solution is illustrated by the drawing, where in FIG. 1 is a schematic diagram of a plant implementing the thermal decomposition of waste containing uranium 235 compounds.

The installation comprises a waste preparation device 1 with a moving device 2, a discrete gateway loading device 3, a thermal decomposition chamber 4 equipped with an external heater 5 and a continuous moving device 6, a discrete gateway device for unloading coke residue 7, a hopper box 8, a burner device 9, catalytic afterburner 10, heat exchanger 11, cyclone 12, wet scrubber 13, exhaust fan 14.

Installation works as follows:

The thermal decomposition chamber 4 is preheated using an external heater 5. From the waste preparation device 1, a portion of waste weighing no more than 2.5 kg is transferred by a moving device 2 to a discrete loading lock device 3. After the transfer of the waste portion to the lock loading device 3 is completed, it is closed upper shutter and open the lower shutter. After emptying the gateway device 3, close its lower shutter, open the upper shutter and the loading operation is repeated. Waste from the sluice device 3 is poured onto the input section of the constantly operating moving device 6 of the thermal decomposition chamber 4 and then it is uniformly fed into the inner volume of the chamber. As the waste moves along the axis of the heated thermal decomposition chamber 4 to its exit, the waste gradually heats up, pyrolyzes, and turns into gaseous products and a solid coke-ash residue. At the exit from the thermal decomposition chamber 4, the coke ash residue uniformly enters the lock device 7, and gaseous products evenly enter the burner device 9. After filling the lock device 7 with the specified mass of the coke ash residue, open its lower gate and discharge the coke ash residue into the hopper box 8. By the time the gateway device 7 is filled with the specified mass of coke-ash residue in the gateway loading device 3, a new portion of the waste is prepared and the operations are repeated.

After the combustion of gaseous products in the burner 9, the resulting flue gases enter the catalytic afterburner 10, where the organic residues are catalytically burned, and then into the shell-and-tube heat exchanger 11. The flue gases cooled in the heat exchanger 11 are cleaned of dust in a cyclone 12 and washed in a “wet” scrubber 13 and through the exhaust fan 14 are removed from the process.

The supply of the thermal decomposition chamber 4 with a lock loading device 3 and a lock device for unloading coke ash residue 7 eliminates the possibility of air entering from the external environment into the thermal decomposition chamber 4 and, conversely, gaseous pyrolysis products from the thermal decomposition chamber 4 into the external environment.

The supply of the thermal decomposition chamber 4 with an internal continuous transfer device 6 ensures uniform movement of the waste in the thermal decomposition chamber 4 and, as a result, an almost uniform steady state heating and pyrolysis of the waste over the temperature zones of the thermal decomposition chamber 4, which in turn ensures a uniform supply of gaseous products pyrolysis of a full-time device 9 burned. In turn, a uniform supply of flue gases to the heat exchanger 11 allows the production of s of cooling time in a uniform one heat exchanger, thereby avoiding the need to use multiple heat exchangers for the removal of such large amounts of heat in a short period of time with "volley" separation of the pyrolysis products. In addition, there is no need for a sharp increase in the flow rate of the cooling medium supplied to the heat exchanger, with the "volley" allocation of pyrolysis products. The consequence of this is a decrease in the total metal consumption of the installation and energy savings

The supply of the thermal decomposition chamber 4 with a discrete loading lock device 3 with a continuously operating transfer device 6 and the installation of units in accordance with nuclear safety requirements preclude the possibility of accumulating a critical mass of uranium compounds during the process.

Thus, the claimed technical solution reduces the metal consumption of heat exchange equipment and saves energy due to the uniformity of the cooling of the combustion products, makes it impossible for air to enter the thermal decomposition chamber by supplying waste to the thermal decomposition chamber, and removes coke ash residue through discrete gateway feeders and makes it impossible the accumulation of a critical mass of uranium 235 due to the implementation of the installation nodes in accordance with nuclear safety concerns.

Claims (2)

Installation for the disposal of waste, including uranium compounds, containing a thermal decomposition chamber with external heating, a burner, a catalytic afterburner, a heat exchanger, a dust cleaning system, and a smoke exhauster, characterized in that the entrance to the thermal decomposition chamber is equipped with a discrete loading gateway device, the chamber has an internal volume of thermal decomposition is equipped with a continuous moving device; the exit from the thermal decomposition chamber is equipped with a coxo sluice discharge device of the residual residue and the vapor-gas mixture removal device connected to the burner device, the output of which is connected to the entrance to the catalytic afterburner, the output of which is connected to the entrance to the heat exchanger, and all the geometrical dimensions of the units are made in accordance with nuclear safety requirements, eliminating the possibility of critical accumulation masses of uranium compounds during the process. 2. Installation according to claim 1, characterized in that the internal volumes of all the units of the installation do not exceed 4 liters, and their transverse dimensions do not exceed 110 mm.