RU2797576C1 - Pellet sintering plant containing a transport channel - Google Patents

Abstract

FIELD: nuclear energy.

SUBSTANCE: equipment for sintering fuel pellets, intended to confirm the parameters and design solutions adopted in the development of the technical design of the plant. The pellet sintering plant consists of a transport channel, includes modules for loading 1 and unloading 4 carts with boats filled with pellets, a sintering oven 2, a refrigerator 3 and a gas cleaning unit 6. The transport channel for moving the pellets is formed by the internal chambers of the loading module 1, the unloading module 4, the refrigerator 3 and the internal channel of the sintering furnace 2, made in the form of a retort, articulated into a single whole. The loading module 1 is separated from the sintering pellet furnace 2 by a gate 8 with a gas barrier. Gates 9, 10, 11 of similar design are installed between the refrigerator 3 and the unloading module 4, as well as at the inlet to the loading module 1 and the exit from the unloading module 4, respectively.

EFFECT: increasing the reliability of operation of the main design solutions of the plant with the provision of a given performance of the working cycle.

6 dwg

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The invention relates to the field of nuclear energy, in particular to technological non-standardized equipment for the manufacture of pellets of uranium-plutonium fuel (SNUP and MOX fuel) and is intended to confirm the parameters and design solutions adopted in the development of a technical design for a pellet sintering plant, taking into account the possibility of its service by a robotic complex in the conditions of robotic production of uranium-plutonium fuel.

BACKGROUND OF THE INVENTION

The standard process for making fuel pellets for nuclear reactors is to form uranium-plutonium oxide or nitride powders into green pellets, which are then sintered to the required density. Sintered pellets are subject to fairly stringent requirements for density, microstructure, thermal stability, and other parameters, which are ensured by appropriate technological processes on special technological equipment, mainly in the form of gas-filled multi-chamber resistive heating furnaces.

From the prior art, a device is known for implementing a method for manufacturing pelletized fuel from uranium dioxide (RU 2158030 C2, G21C 3/62, 2000), in which the sintering mode is provided by advancing boats with tablets in a tunnel-type furnace operating in continuous mode and having three temperature zones : heating and removing the binder, sintering tablets in a reducing environment and cooling.

However, with this method, the sintering of tablets begins long before the maximum temperature is reached. In this case, first of all, sintering and compaction of the surface layers of the tablet occurs. The compacted sintered surface layer of the tablet makes it difficult for the release of gaseous products formed during the decomposition of binders, which leads to cracking and destruction of the tablets.

There is also known a method for the manufacture of pelletized fuel for fuel elements (RU 2256245 C2, G21C 3/62, 2005), which implements the sintering of pellets by gradual, longer preparation of pellets for subsequent heat treatment in a tunnel-type furnace with three sections of heating, sintering and cooling, which have nine temperature zones. In the first three zones, the “raw” tablets are gradually heated, preparing them for subsequent heat treatment, in the fourth and fifth zones, the tablets are further heated, in the sixth and seventh zones, tablets are sintered, in the eighth zone, tablets continue to be sintered with hydrogen afterburning, in the ninth zone cool the tablets with a drop in temperature.

With this technology of sintering tablets, due to the longer preparation of tablets for sintering, the quality of tablets increases and the yield increases. On the other hand, it is necessary to preheat the tablets for 4-5 hours, to keep the tablets in the high-temperature zone for up to 6 hours, and to bring the duration of complete removal of the binder to the residual up to 14 hours. At the same time, the entire tablet production cycle from loading into the oven to unloading from the oven will take 30-35 hours, which lengthens the technological process and reduces its productivity, which in turn does not allow the implementation of a more modern technology for sintering tablets in pusher-type furnaces with the possibility of their maintenance by robotic technology. complex.

In this case, it is advisable to remove the binder in a separate furnace, and sinter the tablets in another furnace, moving the boats with tablets along a common transport channel.

From the prior art, a method is known for sintering pellets into fuel pellets and a device for implementing this method (US 4655978 A, G21C 3/62, 1987), in which the pellets are moved along a transport channel made in the form of a muffle of a tunnel furnace by forcing the pellets through the muffle on the guide a device mounted at the entrance to the muffle and containing boats for loading pellets into them.

The well-known technical solution of the sintering furnace according to the invention US 4655978 A can be taken as the closest analogue (prototype) in terms of the largest number of essential features identical with the claimed invention.

The disadvantage of the prototype lies in the complexity of the design of the well-known furnace due to the use of a specific technology for the manufacture of fuel pellets from pellets of primary raw materials, followed by sintering in the form of a fuel column in the same multi-zone resistive heating tunnel furnace of the pusher type, using a single transport channel for moving the boats.

DISCLOSURE OF THE INVENTION

The objective of the claimed invention is to create a tablet sintering plant of a simplified design, containing a single transport channel in order to confirm the parameters and design solutions adopted in the development of the technical design of the sintering plant, including:

- the possibility of heating the working retort to a maximum temperature of up to 1900 degrees. WITH;

- the possibility of accident-free cyclic loading, unloading and movement of transport carts with boats through the retort at a temperature of 1100 degrees. WITH;

- the possibility of optimizing the supply and maintenance of the gaseous medium into the body and retort of the sintering furnace and the body of the chambers of the loading / unloading modules;

- the possibility of effective cooling of transport carts with boats to a given temperature parameter in a given time period;

- the possibility of servicing individual units of the installation by a robotic complex in the conditions of robotic production of uranium-plutonium fuel.

The technical result is to increase the reliability of the operation of the main units and mechanisms of the tablet sintering plant with the provision of the specified productivity of the working cycle.

The task set can be realized, and its technical result can be achieved by means of a specific technical solution of the invention, which consists in the fact that the tablet sintering plant, containing a transport channel, mainly for moving sintered tablets, includes loading / unloading modules for carts with boats filled with tablets, tablet sintering oven, refrigerator and gas cleaning unit. The transport channel for moving the tablets is formed by the internal chambers of the loading module, the unloading module, the refrigerator and the internal channel of the tablet sintering furnace, made in the form of a retort, articulated into a single whole. The loading module is separated from the tablet sintering furnace by a gate with a gas barrier, gates of similar design are installed between the cooler and the unloading module, as well as at the entrance to the loading module and the exit from the unloading module, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by drawings:

figure 1 - General view of the plant sintering tablets;

figure 2 - loading module;

figure 3 - furnace sintering tablets;

figure 4 - shipping container;

Fig.5 - gate with a gas barrier;

Fig.6 - installation of gas cleaning.

IMPLEMENTATION OF THE INVENTION

Further, with reference to the accompanying drawings, a preferred embodiment of the claimed invention is described.

As can be seen from figure 1, the claimed invention of a tablet sintering plant containing a transport channel includes a loading module 1, a tablet sintering furnace 2, a refrigerator 3, an unloading module 4, a gas cleaning unit 6 for regulating and supplying gas to the tablet sintering plant. The internal chambers of the loading module 1, the unloading module 4, the refrigerator 3 and the internal channel of the pellet sintering furnace 2, made in the form of a retort, articulated together into a single whole, form a transport channel for moving sintered pellets.

The unit is mounted on a base 5, in the lower part of which there is a water-gas panel 12 and connectors 13 for supplying water, gases and electricity to the unit.

The loading module 1 is separated from the tablet sintering furnace 2 by a gate 8 with a gas barrier. The same gate 9 is installed between the refrigerator 3 and the unloading module 4. Similar gates 10 and 11 are installed at the entrance to the loading module 1 and the exit from the unloading module 4, respectively.

Figure 2 shows the loading module 1. The module includes a body 14, a linear displacement drive 15, a manipulator 16 and a linear drive 17 with a table 18. The body 14 has flanges 19 and 20. The design of the unloading module 4 is similar to the design of the loading module 1, while the modules loading / unloading 1, 4 are mounted mirror to each other.

Figure 3 shows a pellet sintering furnace 2. The furnace includes a housing 21 with thermal insulation 22 and a water cooling system 23 in the form of a casing 24 mounted on the outer surface of the housing 21, inside which the coolant circulates. The housing 21 is divided into parts by heat-insulating partitions 25 according to the number of thermal zones. The furnace is equipped with heaters 26 and thermoelectric converters 27, which provide heating, maintaining and controlling the temperature regime.

Covers 28 and 29 are installed on both end parts of the housing 21, hermetically isolating the internal cavity of the housing 21. Inside the housing 21 there is a through retort 30 with exhaust pipes 31, through which the gases of the processed product are removed. The heaters 26 with their flange part are hermetically installed in the housing 21 with quick-release clamps 33. A cooler 34 with a bellows 35 is attached to the end cover 29.

4 shows a shipping container 32. The shipping container 32 includes a shipping cart 36 with a boat 37 filled with fuel pellets. The transport cart 36 has rollers 38 to allow the transport container 36 to move along the retort 30.

Figure 5 shows a gate with a gas barrier. The gate 9 contains a sealed housing 38, flanges 39 and 40, a slide gate 41 with screens 42 attached to the gate 41 from the side of the sintering furnace 2 and dividing the internal cavity of the housing 38 into two parts. Slide gate 41 is installed with the possibility of vertical movement with the help of an actuator 43. Gas is supplied to the internal cavity of the housing through pipes 44, creating a gas curtain.

Figure 6 shows the installation of gas cleaning. The gas cleaning unit 6 contains two gas cleaning units 45 connected through pipelines 46 to a three-way valve 47, which allows switching the gas flow from one unit to another. The gas cleaning unit 45 consists of gas cooled traps 48 and filters 49. Thermoelectric converters 50 make it possible to control the temperature of the gases passing through the traps 48. Water is supplied through the supply 51 and drainage 52 pipelines to the traps 48 to cool the traps and gases passing through them. Valves 53 allow you to control the flow of water, and sensors 54 control the parameters of the outgoing water and send a signal to valves 53.

The principle of operation of the tablet sintering unit is as follows.

The transport container 32 with tablets from the external transport corridor enters the loading module 1 through the open gate 41 of the gate 10, in which it is reloaded onto the table 18 with the help of a manipulator 16, and then with the help of a linear drive 17 it moves to the loading zone of the sintering furnace 2 in the direction of the gate 8 This closes the gate 10 and purges the loading module with process gas, providing an inert atmosphere in the loading module 1.

Next, gate 8 opens and container 32 with trolley 36 and boat 37 is pushed into retort 30 of sintering furnace 2 by linear displacement drive 15. Gate 8 closes, blocking the communication of the atmosphere in retort 30 with the atmosphere in loading module 1. The cycle of loading one boat with tablets into the retort ended. Similarly, sequential loading of the remaining containers 32 is carried out.

In the process of moving a string of containers 32 with boats 37 along the retort 30 in the sintering furnace 2, the tablets are heated stepwise to a predetermined temperature. In this case, the reaction products are removed through the exhaust pipes 31, which enter the gas cleaning unit 6. The sintered pellets are cooled in the refrigerator 3.

When the container 32 is pushed out of the refrigerator 3, the gate 9 opens and the container 32 enters the unloading module 4. The gate 9 closes, interrupting the communication of the gas medium in the unloading module 4 and the sintering furnace 2 with the refrigerator 3. The principle of operation of the components and mechanisms of the unloading module 4 is similar to the principle of operation loading module 1. Next, the gate 11 opens and one container 32 with the boat 37 is unloaded.

Similarly, all other containers 32 are sequentially unloaded with boats 37 containing cooled sintered pellets.

The above-described working process of sintering fuel pellets, provided that the required parameters of the main technological characteristics, due to the specified mode of operation, are ensured, it guarantees an increase in the reliability of the operation of the main design solutions of the pellet sintering plant with the specified productivity.

Claims (1)

Tablet sintering plant containing a transport channel, mainly for moving sintered tablets, including modules for loading / unloading carts with boats filled with tablets, a tablet sintering oven, a refrigerator and a gas cleaning unit, characterized in that the transport channel for moving tablets is formed articulated with each other in a single unit internal chambers of the loading module, the unloading module, the refrigerator and the internal channel of the tablet sintering furnace, made in the form of a retort, while the loading module is separated from the tablet sintering furnace by a gate with a gas barrier, gates of similar design are installed between the refrigerator and the unloading module, as well as at the inlet into the loading module and exiting the unloading module, respectively.

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