RU219181U1 - Device for extracting plutonium dioxide bottom sediment from the precipitator - Google Patents

Abstract

The utility model can be used in the purification of liquids from sediments in the process of nuclear fuel reprocessing. The device for extracting plutonium dioxide bottom sediment from the precipitator contains a pneumatic drive 7 and a bearing assembly 8 fixed on the rotor shaft. The rotor is made in the form of a hollow cylinder, the lower part of which has the shape of a truncated cone with a hole in the lower central part and holes 5 in the upper end for fluid flow. A fixed cup 3 is fixed on the body of the device 2, mounted coaxially outside the rotor 9. The rotor 9 is driven by a pneumatic drive 7 by supplying compressed air. The bearing assembly is located in the neck of the precipitator and contains a tube 10 for supplying compressed air after a pneumatic drive to cool the bearing assembly and a tube 11 for removing excess air from the bearing assembly. The technical result makes it possible to increase the reliability of the device for extracting bottom sediment. 1 w.p. f-ly, 1 ill.

Description

The utility model relates to devices for cleaning various liquids from coarse sediments and fine suspensions and can be used, in particular, in the nuclear power industry during the processing of nuclear fuel by a pyrochemical precipitation method in molten salts.

A device is known, described in patent No. 2236307 IPC B04B1 / 00, 11/04, 15.12, G21C 19/42 2004, which contains a drive, a bearing assembly, a rotor mounted on a shaft, and a base plate. The rotor of the device has the shape of a cylinder with a plugged upper end and a narrowing in the lower part in the form of a truncated cone with a central hole and windows in the upper part of the rotor. The rotor is surrounded by a fixed cylinder with holes in the side. The device is immersed directly into the liquid to be clarified, and by rotating the rotor, the liquid is circulated through its internal cavity, while sucking up sediments and suspensions and thus settling the solid phase inside the rotor. Then the rotor is raised above the liquid surface and the sediment is squeezed out of the trapped liquid. After that, the rotor with sediment is moved into a washing liquid to wash the sediment from impurities, and then, to unload the product, the rotor is moved into a volatile liquid and the sediment is washed out of the rotor.

The use of this device in the processing of nuclear fuel by the pyrochemical precipitation method in molten salts implies the presence of high radiation fields when working with highly irradiated and short-aged spent nuclear fuel, which can lead to the fact that the electric motor in conditions of powerful radiation fields can fail and this will require process shutdown for motor replacement. Therefore, it becomes necessary to use other engine options. In the claimed technical solution, this problem is solved by using a pneumatic drive as a motor that rotates the rotor.

As an analogue of the proposed device, a device for extracting solid sediments and suspensions from liquid media (RF patent No. 135936 MPK B01D 21/26, B04V 1/00 2013) a rotor in the form of a hollow cylinder with a narrowing in the form of a truncated cone with a central hole in the lower part and windows in the upper end. Holes are made on the side surface of the outer stationary cylinder, and a helical spiral is made on the outer side surface of the rotor, wound in the direction of rotation of the rotor.

In the conditions of fulfilling the requirements of nuclear safety, there are restrictions both on the diameter of the equipment and on the volume of the working environment in which technological processes are carried out. This analog, when used to extract sediment from molten salts in the form of highly active melts, requires an increase in the length of the shaft to eliminate the effects of high temperature and radiation on the drive. This imposes additional requirements on the dimensions of the radiation shielding chamber in which this facility will be used, which may require an increase in capital costs to increase the size of the radiation shielding chamber.

Salt melts have a high viscosity, which imposes additional requirements on the strength of the shaft of the device, and this, in turn, leads to a decrease in its length. The presence of a shaft that is too long complicates the movement, transportation, and storage of the device inside the radiation-protective chamber, which makes it urgent to create a more compact device.

The inventive device for extracting plutonium dioxide bottom sediment from the precipitator, as well as analogue, contains a drive, a bearing assembly. The design of the apparatus is represented by a rotor (collector glass) with a narrowing in the form of a truncated cone, fixed on a shaft located inside a fixed cylinder, on the side surface of which holes are made. In the upper part of the rotor, like the analog, there are windows and a central hole located at the bottom of the rotor.

However, unlike analog, it is proposed to place the bearing assembly in the neck of the precipitator, and this will inevitably lead to high temperature exposure from the salt melt, which will require additional cooling, which is proposed to be carried out by supplying compressed air. An additional difference between the claimed device and its analogue is that a pneumatic drive is used, after which compressed air is supplied to cool the bearing assembly, which ensures its reliable operation under operating conditions in an aggressive environment at a temperature in the range from 450°C to 650°C. Due to this cooling design, the bearing assembly is fixed not on the base plate, as in the analogue, but directly in the neck of the precipitator.

An important advantage of the proposed technical solution is that, due to the reduced cantilever length of the shaft, the load on the shaft bending is reduced, which makes it possible to make it more compact compared to its counterpart. This design simplifies the possibility of intra-chamber transportation of the device, and also expands the possibilities of its use in different devices or technological processes.

In addition, to improve the mulching of the sucked liquid through the lower central hole of the rotor, grooves are made on the inner surface at the lowest point of the rotor near the central hole in such a way as to create sufficient turbulence necessary to lift coarse sediments and fine suspensions located at the bottom of the precipitator.

The figure schematically shows the claimed device:

1 - shaft;

2 - device case;

3 - fixed glass;

4 - holes in a fixed glass;

5 - holes in the rotor;

6 - grooves for creating turbulence;

7 - pneumatic drive;

8 - bearing assembly;

9 - rotor (glass-collector);

10 - tube for supplying compressed air to cool the bearing assembly;

11 - tube for removing excess air from the bearing assembly.

The device for extracting plutonium dioxide bottom sediment from the precipitator contains a shaft 1, a body of the device 2, a fixed cup 3 with holes 4 on its side surface, a rotor 9 with holes 5 on its side surface, a pneumatic drive 7, a bearing assembly 8, tubes 10 for supplying compressed air to cool the bearing assembly 8 and tube 11 to remove excess air from the bearing assembly 8.

The rotor 9 is made in the form of a hollow cylinder. The lower part of the rotor 9 has the shape of a truncated cone with a hole in the lower central part and holes 5 in the upper end for fluid flow.

The fixed cup 3 is fixed on the body 2 of the device and installed coaxially outside the rotor 9.

The pneumatic actuator 7 is configured to ensure the movement of the rotor 9 by supplying compressed air.

The bearing assembly 8 is located in the neck of the precipitator and contains a tube 10 for supplying compressed air after the pneumatic drive for cooling the bearing assembly 8 and a tube 11 for removing excess air from the bearing assembly 8.

In a particular case of the device execution, grooves 6 are made at the lowest point of the rotor 9 near the central hole 5.

The device is placed inside the precipitator in such a way that the movable rotor 9 is completely immersed in a liquid medium (molten salt).

After the compressed air is supplied to the pneumatic drive 7 through the shaft 1, the rotor 9 is set in rotation, and the compressed air is supplied through the tube 10 to cool the bearing assembly 8.

When the rotor 9 rotates, immersed in the melt, the melt is sucked along with the bottom sediment into its internal cavity. Due to centrifugal forces, the sediment is pressed against the inner wall of the rotor 9. The liquid (molten salt) is removed from the rotating rotor 9 through the holes 5 in its upper part into the annular space between the rotor 9 and the fixed glass 3. The melt from the annular gap between the moving and stationary parts through special holes 4 in the lower part of the stationary glass 3 returns to the volume of the precipitator and stirs up the sediment, providing circulation of the suspension through the volume of the hollow rotor 9. The grooves 6 in the lower part of the rotating rotor help to raise the bottom sediment from the bottom of the precipitator. Excess air is removed from the bearing assembly through the tube 11. Thus, the device is intensive mixing of the melt with the bottom sediment and repeated circulation of the suspension through the cavity of the rotating rotor. In this case, the sediment is quantitatively collected on the inner surface of the rotor 9.

After collecting the bottom sediment, the rotation frequency is reduced, the device is removed from the molten medium and kept in the precipitator above the melt, without stopping the rotation of the rotor 9 until the salts together with the sediment solidify in the internal cavity of the rotor 9.

The design of the device makes it possible to exclude the effect of high temperatures from molten salts on it due to cooling with compressed air supplied from a pneumatic drive, and sufficient turbulence necessary to lift coarse sediments and fine suspensions located at the bottom of the precipitator.

The device can be used to recover from the melt precipitation of impurity elements (oxides, phosphates, etc.) obtained during periodic purification of the electrolyte.

The technical result is an increase in the reliability of the device due to the placement of the bearing assembly in the neck of the precipitator and the arrangement of tubes for supplying air to cool the bearing assembly and for removing air from it.

Claims (2)

1. A device for extracting plutonium dioxide bottom sediment from a precipitator, containing a drive, a bearing assembly, a rotor mounted on a shaft in the form of a hollow cylinder, the lower part of which has the shape of a truncated cone with a hole in the lower central part and holes in the upper end for liquid overflow , and a stationary glass fixed on the body of the device, mounted coaxially outside the rotor, on the side surface of which holes are made, characterized in that the drive is pneumatic and is configured to ensure the movement of the rotor due to the supply of compressed air, while the bearing assembly is located in the neck of the apparatus - precipitator and contains a tube for supplying compressed air after the pneumatic drive to cool the bearing assembly and a tube for removing excess air from the bearing assembly. 2. The device according to claim 1, characterized in that grooves are made at the lowest point of the rotor near the central hole.

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