阅读说明：本技术 通过减少六氟化铀的热解生产二氧化铀粉末的反应室 (Reaction chamber for producing uranium dioxide powder by reducing pyrolysis of uranium hexafluoride ) 是由 D·Y·奥斯特罗夫斯基 A·L·克莉汀 Y·V·奥斯特罗夫斯基 G·M·扎博采夫 I·I·哲 于 2019-09-05 设计创作，主要内容包括：本发明涉及用于生产金属化合物的方法,即,通过减少热解将六氟化铀(UF6)转化为陶瓷二氧化铀(UO2)粉末(U235富集率高达5％)的装置。本发明的实质：反应室是带有上盖和下盖的壳体。有一个上部过滤区,其中设有金属陶瓷过滤器,用氮气再生。有第一反应区用于将六氟化硫转化为氟化铀。有第二个反应区设有气体分配网,用于创建流化床,用于通过蒸汽、氢气和氮气混合物的进料管将氟化铀还原为二氧化铀。在反应室主体的第一反应区的侧壁上,用于供应六氟化铀、氢气和水蒸气的两个喷嘴对称布置。反应室配备了用于卸载粉末的装置。供应六氟化铀、氢气和水蒸气的喷嘴可在垂直平面内移动。另外,这些喷嘴可以单独使用：一个喷嘴可以是供应六氟化铀的入口,第二个喷嘴可以是供应氢气和水蒸气的入口。所提出的反应室可以解决以下问题：增加维修之间的反应室的使用寿命,增加滤芯的使用寿命,通过消除中间体的积累提高其生产率。(The invention relates to a method for producing metal compounds, namely a device for converting uranium hexafluoride (UF6) into ceramic uranium dioxide (UO2) powder (U235 enrichment of up to 5%) by means of reduced pyrolysis. The essence of the invention is as follows: the reaction chamber is a housing with an upper cover and a lower cover. There is an upper filtration zone in which a cermet filter is placed, regenerated with nitrogen. There is a first reaction zone for converting sulphur hexafluoride to uranium fluoride. There is a second reaction zone provided with a gas distribution network for creating a fluidized bed for reducing uranium fluoride to uranium dioxide through the feed of a mixture of steam, hydrogen and nitrogen. On the side wall of the first reaction zone of the reaction chamber body, two nozzles for supplying uranium hexafluoride, hydrogen and water vapor are symmetrically arranged. The reaction chamber is equipped with means for unloading the powder. The nozzle supplying uranium hexafluoride, hydrogen and water vapour is movable in a vertical plane. In addition, these nozzles can be used alone: one nozzle may be an inlet for supplying uranium hexafluoride and a second nozzle may be an inlet for supplying hydrogen and water vapour. The proposed reaction chamber can solve the following problems: increase the service life of the reaction chamber between repairs, increase the service life of the filter element, and increase the productivity thereof by eliminating the accumulation of intermediates.)

1. Reaction chamber for the production of uranium dioxide powder by means of pyrohydrolysis for the reduction of uranium hexafluoride, having an upper cover and a lower cover, having an upper filtering zone equipped with a cermet filter regenerated with nitrogen, having a first reaction zone for the conversion of uranium hexafluoride into uranium fluoride and a second reaction zone with a gas distribution network for the creation of a fluidized bed for the reduction of uranium fluoride into uranium dioxide, having a conduit for supplying a mixture of steam, hydrogen and nitrogen, and having a nozzle for supplying uranium hexafluoride, hydrogen and water vapour, located on a side wall of the first reaction zone of the housing, and having a device for unloading powder from the reaction chamber, an important difference being that the body of the reaction chamber is additionally equipped with a second nozzle for supplying uranium hexafluoride, hydrogen and water vapour, located on a wall of the first reaction zone of the body, symmetrical to the first.

2. A reaction chamber as claimed in claim 1 wherein the nozzle for supplying uranium hexafluoride, hydrogen and water vapour is movable in a vertical plane.

3. A reaction chamber as claimed in claim 1 wherein one nozzle is used as an inlet for the supply of uranium hexafluoride and a second nozzle is used as an inlet for the supply of hydrogen and water vapour.

Technical Field

The invention relates to a method for producing metal compounds, namely a device for converting uranium hexafluoride (UF6) into ceramic uranium dioxide (UO2) powder (U235 enrichment rate is up to 5%) by reducing pyrolysis.

The process is described by the following chemical reaction:

UF_6(g)+2H₂O_(g)→UO₂F_2(g)+4HF_(g) (1)；

UO₂F_2(g)+H_2(g)→UO_2(g)+2HF_(g) (2).

background

In the technical field, plants are known for the production of uranium dioxide powder from uranium hexafluoride. It comprises a reaction chamber for the formation of uranium fluoride by hydrolysis of uranium hexafluoride in the presence of water vapour. It also has a rotating tube furnace connected to it for the subsequent production of uranium dioxide by reduction of uranium fluorides and hydrogen. It has a device for heating and supplying water vapor and hydrogen gas in a counter-current manner (see Russian patent No. 2162058).

The disadvantage of this installation is that the separate chemical reactions for the production of uranium oxide are divided into several stages. They are implemented in different nodes. This results in an increase in installation size and an increase in operating costs. The technical essence and the achievement of the invention are closest to the plants for the production of uranium dioxide powder from uranium hexafluoride by means of pyrolysis. It has a heated reaction chamber. The reaction chamber has a filtration zone with a filter regeneration system. It also has a first reaction zone for converting uranium hexafluoride to uranium fluoride and a second reaction zone with a gas distribution network for creating a fluidized bed for reducing uranium fluoride to uranium dioxide. There is also a device for unloading the uranium dioxide powder obtained (see russian patent No.2381993) which is a prototype).

A disadvantage of this device is that intermediate deposits of uranium hexafluoride converted into dioxide are formed on the walls of the reaction chamber and the filter element. These deposits consist mainly of uranium fluoride and nitrous oxide. The solid deposits were located in the upper corner of the filtration zone. It is located opposite the nozzle for supplying a mixture of uranium hexafluoride, hydrogen and water vapour. The localized position is caused by the interaction of the uranium hexafluoride, hydrogen and water vapor mixture (which is delivered to the reaction zone through the nozzle) and the water vapor, hydrogen and nitrogen mixture (which enters the lower reaction zone below the gas distribution grid).

During this interaction, a non-uniform loading of the filter elements of a fine fraction of solid product particles of uranium hexafluoride pyrolysis (UO2F2, U3O8 and others) was observed within the reaction chamber. Therefore, filter regeneration systems that are back flushed with nitrogen do not always cope with the task of ensuring that the filter is fully regenerated. In particular the filters, the solid deposits which accumulate in the region of the filtering zone located in the upper corner.

Due to the incomplete regeneration of the filters, they gradually become clogged by the uranium hexafluoride pyrolysis products. As a result, the hydraulic resistance of the entire reaction chamber increases. This results in the need to stop the process for long periods of time to cool the reaction chamber and replace the cermet filter.

The intermediates of the uranium hexafluoride pyrolysis reaction are formed primarily due to the lack of reaction time (i.e., the reaction necessary to form uranium fluoride particles). The particles can be moved independently from the first reaction zone to the second reaction zone where the uranium fluoride particles are reduced to uranium dioxide in the fluidized bed).

The lack of reaction time results in the formation of small fractions of uranium fluoride and dinitrogen monoxide-uranium oxide, and their dense accumulation in the filtration zone. This inevitably leads to clogging of the filter element.

Disclosure of Invention

The technical aim of the present invention is to increase the operating time of the reaction chamber (between repairs), as well as to increase the service life of the filtering element and to increase the productivity of the chamber by minimizing the formation of intermediates.

This problem is solved by the fact that in the reaction chamber for obtaining uranium dioxide powder by reducing the pyrohydrolysis of uranium hexafluoride, there is a zone equipped with an upper and a lower lid and having:

an upper filtering zone (which has a cermet filter regenerated by nitrogen). The first reaction zone is used for converting sulfur hexafluoride into uranium fluoride. At the same time, a nozzle for supplying uranium hexafluoride, hydrogen and water vapor is provided in the first reaction zone on the side wall of the body. A second reaction zone having a gas distribution grid for creating a fluidized bed for reducing uranium fluoride to uranium dioxide. There is a pipe for supplying a mixture of steam, hydrogen and nitrogen. There is a device for unloading the powder. According to the invention, the first reaction zone of the chamber additionally has a second nozzle for supplying uranium hexafluoride, hydrogen and water vapour. The first nozzle is located on the side wall of the housing symmetrically.

This task is also solved as follows: the two nozzles for supplying uranium hexafluoride, hydrogen and water vapour are movable in a vertical plane. These objectives are also achieved when one nozzle of the first reaction zone supplies uranium hexafluoride and the other nozzle supplies equal amounts of hydrogen and water vapor.

The first reaction zone of the reaction chamber body has additional nozzles for supplying uranium hexafluoride, hydrogen and water vapor. It is located symmetrically on the nozzle on the body of the reaction chamber. This makes it possible to equalize the gas flow in the upper filtering zone, parallel to its walls, and to ensure the small particles provided during the pyrolysis of the uranium hexafluoride on a uniform load of the filter. In other words, this ensures uniform regeneration of all filters during the back purge and eliminates rapid overgrowth of filters produced by the high temperature hydrolysis products of uranium hexafluoride.

If the nozzle for supplying uranium hexafluoride, hydrogen and water vapour is moved in a vertical plane, this will allow you to adjust the angle of the nozzle. This will allow for adjustment of the time that the resulting fluorourethane particles are located in the first reaction zone. This will also affect the formation of solid particles of the desired size. Furthermore, the conditions for forming nitrous oxide-uranium oxide by reaction (3) will be minimized, and therefore the load on the entire filter element will be reduced:

3UO₂F_2(g)+ЗН₂O_(g)→U₃O_8(g)+1,5O_2(g)+6НF_(g) (3)

supplying hydrogen to the first reaction zone through an additional nozzle will increase the concentration of hydrogen and increase the rate of the pre-recovery reaction of uranium fluoride and nitrous oxide-uranium oxide particles in reactions (2) and (4):

U₃O_8(g)+2H_2(g)→3UO_2(g)+2Н₂O_(g) (4)

the hydrodynamic conditions of the process for reducing the fluorourethane with hydrogen in the "boiling" layer of the second reaction zone are not affected.

Supplying uranium hexafluoride to one nozzle and hydrogen and water vapour to the other nozzle allows more precise control of the supply of each component of the mixture to the reaction chamber. This affects the quality and quantity of the overall process.

Drawings

The essence of the invention is illustrated in the accompanying drawings.

The figure shows a reaction chamber for the production of uranium dioxide powder by pyrolytic reduction of uranium hexafluoride.

The reaction chamber has a housing (1), an upper cover (2) and a lower cover (3), the upper cover (2) carrying a gas distribution grid (not shown). The three units are hermetically connected to each other by a flange connection. A replaceable cermet filter (4) is sealingly fastened to the flange of the upper cover (2). Each cermet filter (4) is equipped with an inlet system (5) which is mounted in the upper cover (2). This is necessary for the nitrogen pulse supply required for filter regeneration. A branch pipe (6) for an exhaust outlet is arranged on the side wall of the compensation volume upper cover (2). The body (1) of the reaction chamber comprises an upper filtering zone, a first reaction zone (8) for converting sulphur hexafluoride into uranium fluoride and a second reaction zone (9) for creating a fluidized bed for reducing uranium fluoride into uranium dioxide. The cermet filter (4) is mounted in the upper filter zone (7). The upper filtering area is positioned at the upper part of the shell (1). The first reaction zone (8) of the reaction chamber body is connected with the filtering zone (7) and the second reaction zone (9). The second reaction zone is a fluidized bed zone. In the first reaction zone (8), two nozzles (10) and (11) are symmetrically placed to supply uranium hexafluoride, hydrogen and water vapour. The lower cover (3) is provided with a branch (12) for supplying a mixture of steam, hydrogen and nitrogen and a branch (13) for the powder discharge device, which branch is connected in a gas-tight manner to the gas distribution network.

Detailed Description

The reaction chamber operates as follows.

The reaction chamber is preheated to a temperature of 450 ℃ to 500 ℃ in the upper filtration zone (7) and the first reaction zone (8), and to a temperature of 580 ℃ to 635 ℃ in the second reaction zone (9). Uranium hexafluoride, hydrogen and water vapour are supplied to the first reaction zone (8) through nozzles (10) and (11). The two nozzles are symmetrically located on opposite walls of the first reaction zone (8) of the housing (1). The introduced reagents react with each other to form a fluorourethane powder. The large particles are reduced into the second reaction zone (9) (fluidized bed zone). These large particles are then captured by the gas distribution grid on the lower cover plate (3). The fine particles rise, are captured by the cermet filter (4), and are periodically regenerated by nitrogen backwash. The fluorourethane particles blown in with nitrogen enter the second reaction zone (9) of the fluidized bed. The mixture of water vapor, hydrogen and nitrogen is sent to the lower part of the gas distribution grid through a pipeline (12) of the lower cover (3). This mixture creates a fluidized bed above the gas distribution grid in which the uranium fluoride is reduced to uranium dioxide. As the uranium dioxide powder accumulates, it is evacuated from the reaction chamber through a nozzle (13), means for unloading the powder from the reaction chamber.

The symmetrical arrangement of the nozzles (10) and (11) ensures that the gas flow in the upper filtering zone (7) is aligned parallel to its walls and that the loading of the filter (4) is uniform. As a result, the operating time between repairs of the reaction chamber increases. Eliminating the accumulation of intermediates results in an increase in the productivity of the reaction chamber.

INDUSTRIAL APPLICABILITY

Therefore, if an additional nozzle is provided in the reaction chamber for producing uranium dioxide powder by reducing the pyrohydrolysis of uranium hexafluoride, it is possible to solve the existing problems. Namely: increasing the operating time between chamber repairs, increasing the useful life of the filter element, and increasing the productivity of the chamber by minimizing the formation of intermediates.