CN115779511A - A solid-liquid separation system for spent fuel reprocessing - Google Patents

Abstract

The invention belongs to the spent fuel reprocessing process, and specifically relates to a solid-liquid separation system for the spent fuel reprocessing process, which is used to separate insoluble solid impurities mixed in the tetravalent uranium feed liquid, including centrifugal equipment and centrifugal equipment connected respectively Feed pipe, discharge pipe and miscellaneous discharge pipe; the centrifugal equipment is a hollow structure; the feed pipe is connected to the upper part of the side wall of the centrifugal equipment, the discharge pipe extends into the inside of the centrifugal equipment, and the miscellaneous discharge pipe is connected to the bottom of the centrifugal equipment; the feed pipe , The discharge pipe and the miscellaneous discharge pipe are respectively equipped with control valves; the tetravalent uranium feed liquid enters the centrifugal equipment from the feed pipe for solid-liquid centrifugal separation, the separated feed liquid is discharged from the discharge pipe, and the solid impurities are discharged from the miscellaneous discharge pipe discharge. Compared with the prior art, the invention can fully separate small insoluble solid impurity particles in the tetravalent uranium feed liquid, and protects high-precision metering pumps and other equipment used in pipelines.

Description

A solid-liquid separation system for spent fuel reprocessing

technical field

The invention belongs to a spent fuel reprocessing process, in particular to a solid-liquid separation system for a spent fuel reprocessing process.

Background technique

In the spent fuel reprocessing process centered on the Purex process, the separation of uranium and plutonium needs to reduce plutonium from tetravalent to trivalent, and then use the difference in the distribution coefficient of hexavalent uranium and trivalent plutonium in TBP to achieve Separation of uranium and plutonium. The currently used reducing agent is tetravalent uranium, which also contains hydrazine as a supporting reducing agent, so that the reduction of plutonium can be achieved without introducing impurities. At present, tetravalent uranium is mainly obtained by electrolytic reduction of hexavalent uranium in an electrolytic cell. After seasoning (adjusting acidity), the tetravalent uranium feed liquid is transported to the buffer tank through a diode pump. It is sent from the buffer tank to the uranium-plutonium separation unit through a high-precision metering pump.

Since the tetravalent uranium feed liquid will contain small insoluble solid impurity particles, during the long-term operation of the system, these small solid particles will gradually accumulate on the pipeline from the tetravalent uranium feed liquid to the uranium-plutonium separation unit, causing the relevant pipelines to be blocked. In turn, the discharge of tetravalent uranium feed liquid is not smooth and the flow rate is unstable, which leads to poor separation effect of uranium and plutonium; further, when the blockage is serious, it is very likely to cause damage to the high-precision metering pump, and the tetravalent uranium feed liquid If it does not work at all, it will eventually cause the system to stop, seriously affect the production schedule, and may cause safety accidents. At the same time, the frequent damage of high-precision metering pumps also greatly increases the cost of operation and maintenance.

How to quickly and conveniently separate the small insoluble solid impurities in the tetravalent uranium feed solution to protect the high-precision metering pumps and other equipment in the pipeline has become an urgent problem to be solved.

Contents of the invention

The purpose of the present invention is to provide a solid-liquid separation system for the spent fuel reprocessing process in order to solve at least one of the above problems, which can fully separate the small insoluble solid impurity particles in the tetravalent uranium feed liquid, and protect the High-precision metering pumps and other equipment.

The object of the present invention is achieved through the following technical solutions:

A solid-liquid separation system for the spent fuel reprocessing process, used for separating insoluble solid impurities mixed in the tetravalent uranium feed liquid, including centrifugal equipment and feed pipes, discharge pipes and miscellaneous discharge pipes connected to the centrifugal equipment respectively ;

The centrifugal device is a hollow structure;

The feed pipe is connected to the upper part of the side wall of the centrifugal device, the discharge pipe extends into the inside of the centrifugal device, and the miscellaneous discharge pipe is connected to the bottom of the centrifugal device; the feed pipe, the discharge pipe and the discharge pipe are The miscellaneous pipes are respectively provided with control valves;

The tetravalent uranium feed liquid enters the centrifugal device through the feed pipe for solid-liquid centrifugal separation, the separated feed liquid is discharged through the discharge pipe, and the solid impurities are discharged through the miscellaneous discharge pipe.

The feed end of the feed pipe is connected to the diode pump, and the discharge end of the discharge pipe is connected to the buffer tank, which is equivalent to connecting the solid-liquid separation system of the present invention between the diode pump and the buffer tank in the original process.

The solid-liquid separation system for the tetravalent uranium feed liquid suitable for the spent fuel reprocessing process, including equipment, pipelines and valves, etc., is made of 316L stainless steel, and its standard grade is 022Cr17Ni12Mo2. The acidity of the tetravalent uranium feed solution is about 1mol/L, and this material can resist acid corrosion.

Preferably, the feed pipe is connected to the centrifugal device in a tangential direction tangent to the side wall of the centrifugal device. By designing and processing the feed liquid inlet pipeline, the inlet pipeline (feed pipe) is tangent to the inner wall of the centrifugal equipment, ensuring that the velocity direction of the feed liquid is tangent to the inner wall of the shell after entering the centrifugal equipment, and reducing the impact of the feed liquid and the inner wall degree, thereby reducing the velocity loss of the fluid.

Preferably, the inner sidewall of the centrifugal device is configured as an inclined twill structure, and channels for controlling the movement direction of the feed liquid are formed between adjacent twill lines. A twill structure is set on the inner wall of the housing, so that the flowing fluid can maintain its speed and direction as a circular motion along the inner wall surface, playing an auxiliary role.

Preferably, the inclination angle between the twill structure and the horizontal direction is 30-60°, and the distance between adjacent twill is 5 mm. The pitch of the twill is determined according to the size of the impurity particles. The impurity particles taken out from the blocked pipe are generally not larger than 2mm, and the pitch of the twill must be greater than the particle size of the impurity. Considering the difficulty of processing, it is more appropriate to choose the pitch of the twill to be 5mm. In addition, theoretically speaking, the smaller the inclination angle (angle with the horizontal plane) of the twill structure, the longer the flow time of the fluid in the centrifugal equipment, the slower the separation speed, and the better the separation effect; on the contrary, the shorter the flow time, the better the separation effect Poor, select the inclination range of 30-60°.

Preferably, the centrifugal device includes a cylindrical section and a conical section integrally formed; the conical section is connected below the cylindrical section; solid-liquid separation is performed in the cylindrical section, and solid impurities are collected in the conical section; The feed pipe is connected to the upper part of the side wall of the cylindrical section, the discharge pipe extends from the top of the cylindrical section into the interior of the cylindrical section, and the miscellaneous discharge pipe is connected to the bottom of the conical section. During the separation process, insoluble impurities will gradually accumulate to the bottom of the conical section of the centrifugal equipment, and can be discharged through the drain valve after accumulating to a certain extent.

Preferably, the discharge pipe is set away from the center of the cylindrical section. The outlet pipeline is arranged eccentrically, compared with the design of the outlet pipeline at the center of the shell, the separation effect is significantly improved.

Preferably, the discharge pipe is arranged at the third point of the diameter of the cylindrical section.

Preferably, the outlet pipe extends to half the height of the cylindrical section.

Preferably, a bypass pipe is connected between the feed pipe and the discharge pipe, and the bypass pipe is connected in parallel with the centrifugal device; a bypass valve is provided on the bypass pipe. A bypass line is set up to ensure that the conventional supply of tetravalent uranium feed liquid can be maintained even when the centrifuge equipment is blowing down.

Preferably, the centrifugal device is also connected with a blowback inlet pipe and a blowback exhaust pipe for the blowback and anti-blocking of the solid-liquid separation system; the blowback inlet pipe is provided with a blowback inlet valve, The blowback exhaust pipe is provided with a blowback exhaust valve. Solid-liquid centrifugal equipment is usually prone to clogging. By introducing steam backflushing pipelines and switching corresponding valves, the function of purging and discharging sewage on the inlet and outlet pipes and miscellaneous discharge pipes can be realized, thereby ensuring the continuous operation of the system.

Working principle of the present invention is:

During normal operation, the feed liquid inlet valve and feed liquid outlet valve are opened, and other valves are closed. After the feed liquid enters the centrifugal equipment from the feed pipe, it has a speed along the tangential direction of the inner surface of the shell. Make a circular motion and create a centrifugal effect. Due to the difference in density, the separation of the feed liquid and insoluble impurities is achieved through centrifugation, and then the feed liquid flows out of the centrifugal equipment through the discharge pipe and enters the subsequent connected uranium-plutonium separation unit; the insoluble impurities are deposited at the bottom of the conical structure and are discharged by opening the impurity The valve can discharge the impurities through the drain pipe.

When the centrifugal equipment is blocked or blocked, the centrifugal equipment can be backwashed by opening the steam backflush inlet valve, steam backflush exhaust valve and impurity discharge valve) and closing other valves; If the liquid is transported, the main feed valve and the bypass valve are opened at the same time, and the bypass pipeline is used to ensure the supply of the feed liquid.

Compared with the prior art, the present invention has the following beneficial effects:

By designing and processing the position and structure of the feed pipe and the discharge pipe, the present invention makes the feed pipe tangent to the inner wall of the centrifugal device, ensures that the velocity direction of the feed liquid enters the separation device is tangent to the inner wall of the shell, and reduces the flow rate of the feed liquid. The degree of impact with the inner wall surface, thereby reducing the velocity loss of the fluid; at the same time, a twill structure is set on the inner wall of the shell to maintain its velocity direction for the fluid, so that the material liquid can always move circularly along the inner wall surface, playing an auxiliary role; this The two designs make the material and liquid move in a circular motion at a higher speed in the separation equipment, and better separate the solid and liquid through centrifugal action.

At the same time, the eccentric arrangement of the outlet pipeline, compared with the design of the outlet pipeline at the center of the shell, enables the fluid to have a larger flow section just after entering the centrifugal device, reduces the resistance of the inlet section, and facilitates the fluid to flow tangentially along the wall according to the pre-design , to achieve a better separation effect, the separation effect has been significantly improved. And it is further preferably installed at the third point, so as to avoid the inlet of the outlet pipeline being too close to the wall surface, causing too many impurities to directly leave the centrifugal device through the outlet pipeline during the separation process, resulting in a reduction in the separation effect.

The establishment of the invention can fundamentally solve the problem of poor discharge of tetravalent uranium feed liquid. The invention of this system can filter out the solid impurities in the tetravalent uranium feed liquid to ensure the quality and stable delivery of the tetravalent uranium feed liquid, which is of great significance to the operation of the uranium-plutonium separation unit. At the same time, the invention of this device can greatly extend the service life of the high-precision metering pump and reduce the operating cost.

Description of drawings

Fig. 1 is the structural representation of solid-liquid separation system of the present invention;

Fig. 2 is a structural schematic diagram of the twill structure of the inner wall of the centrifugal device;

In the figure: 1-cylindrical section; 2-conical section; 3-centrifugal equipment; 4-feed pipe; 5-discharge pipe; 6-twill structure; Material liquid outlet valve; 10-bypass valve; 11-impurity discharge valve; 12-feeding main valve; 13-back blowing intake valve; 14-back blowing exhaust valve.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

A solid-liquid separation system for the spent fuel reprocessing process, as shown in Figure 1 and Figure 2, is used to separate insoluble solid impurities mixed in the tetravalent uranium feed liquid, including a centrifugal device 3 and a centrifugal device 3 respectively connected Feed pipe 4, discharge pipe 5 and miscellaneous discharge pipe 7;

The centrifugal device 3 is a hollow structure;

The feed pipe 4 is connected to the upper part of the side wall of the centrifugal device 3, the discharge pipe 5 extends into the inside of the centrifugal device 3, and the drain pipe 7 is connected to the bottom of the centrifugal device 3; the feed pipe 4. The discharge pipe 5 and the miscellaneous discharge pipe 7 are respectively provided with control valves;

The tetravalent uranium feed liquid enters the centrifugal device 3 through the feed pipe 4 for solid-liquid centrifugal separation, the separated feed liquid is discharged through the discharge pipe 5 , and the solid impurities are discharged through the miscellaneous discharge pipe 7 .

More specifically, in this example:

The upstream of the system is connected to the buffer tank, and the downstream is connected to the uranium-plutonium separation unit; all components of the system are made of 316L stainless steel (standard grade is 022Cr17Ni12Mo2), which can resist the acid corrosion of tetravalent uranium feed solution.

As shown in FIG. 1 , the main body of the solid-liquid separation system is a hollow centrifugal device 3 , which is integrally formed by an upper cylindrical section 1 and a lower conical section 2 . Among them, the cylindrical section 1 is the position for solid-liquid separation of the feed liquid and impurities, and the conical section 2 is used to collect solid impurities.

The feed pipe 4 is connected to the upper position of the outer wall of the centrifugal device 3 and connected to the centrifugal device 3 in a form tangent to the inner wall, that is, the extension direction of the feed pipe 4 at the place where it enters the centrifugal device 3 is the tangential direction there . The design of the tangential form makes the velocity direction of the feed liquid entering the centrifugal device 3 also be tangent to the inner wall, and continue to advance against the inner wall, effectively reducing the loss of fluid velocity and kinetic energy caused by the collision between the feed liquid and the inner wall. Further, the inner wall of the centrifugal device 3 adopts a twill structure 6 as shown in Figure 2, which is arranged along the advancing direction of the feed liquid, the direction of the twill has a certain angle with the horizontal direction, and there is a certain interval between the twill, so that the fluid can be kept. The speed and direction of the twill always perform circular motion along the inner wall surface, which plays an auxiliary role; generally speaking, the distance between the twill lines only needs to be greater than the particle size of the impurity particles. In order to facilitate mass production in the factory, the distance between the twill lines can be set at 5mm , to meet the particle size of most of the magazine particles; the angle of the twill can be a suitable angle within 30-60°, so that the impurity particles and the fluid can be effectively separated in the centrifugal equipment. The two structural designs enable the feed liquid to perform circular motion at a higher speed in the centrifugal device 3, and better separate solid and liquid through centrifugal action.

The discharge pipe 5 extends from the top of the centrifugal device 3 into the inside of the centrifugal device 3. Specifically, in this embodiment, the discharge pipe 5 vertically extends from the third point of the diameter into the centrifugal device 3 to the half of the height of the cylindrical section 1. Compared with the design of the discharge pipe 5 at the center of the centrifugal device 3, the eccentric arrangement of the discharge pipe 5 has a significantly improved separation effect.

A waste discharge pipe 7 is connected to the bottom side wall of the conical section 2, and a waste discharge valve 11 is arranged on it for discharging solid particle impurities by opening the waste discharge valve 11 after accumulating a certain amount of impurities.

There is also a bypass pipe connected between the feed pipe 4 and the discharge pipe 5, which forms a parallel connection with the centrifugal device 3, so that the bypass valve can still pass through the centrifugal device 3 during the process of discharging impurities. 10. Send tetravalent uranium feed liquid to the downstream uranium-plutonium separation unit. In order to control each pipeline, a feed liquid inlet valve 8 and a bypass valve 10 are respectively arranged on the two branches of the feed pipe 4 and the bypass pipe formed separately, and the main feed valve 12 is set on the main pipeline, and the discharge pipe 5 The feed liquid outlet valve 9 is arranged on the top, please refer to Fig. 1 for details.

In addition, in order to perform steam blowback, the centrifugal device 3 is also connected with a blowback inlet pipe and a blowback exhaust pipe, on which a blowback intake valve 13 and a blowback exhaust valve 14 are respectively arranged. The blowback inlet pipe is arranged in line with the feed pipe 4 at the part entering the centrifugal equipment 3, and the blowback exhaust pipe is arranged in line with the discharge pipe 5 at the part entering the centrifugal equipment 3. Please refer to Figure 1 for details.

The working principle is:

During normal operation, the feed liquid inlet valve 8 and the feed liquid outlet valve 9 are opened, and other valves are closed. After the feed liquid enters the centrifugal device 3 from the feed pipe 4, it has a speed along the tangential direction of the inner surface of the shell, and the twill structure 6 on the inner wall With the help, make a circular motion along the inner wall and produce a centrifugal effect. Due to the difference in density, the separation of the feed liquid and insoluble impurities is achieved through centrifugation, and then under the feed pressure, the separated feed liquid flows out of the centrifugal device through the discharge pipe 5 and enters the subsequent connected uranium-plutonium separation unit; the insoluble impurities The impurities are deposited at the bottom of the conical structure, and the impurities can be discharged through the exhaust pipe 7 by opening the impurity discharge valve 11 .

When the centrifuge equipment 3 appears to be blocked or blocked, the steam blowback inlet valve 13, the steam blowback exhaust valve 14 and the impurity discharge valve 11) can be opened, and other valves can be closed to backwash the centrifugal equipment 3; At this time, it is necessary to transport the feed liquid, then open the main feed valve 12 and the bypass valve 10 at the same time, and use the bypass pipeline to ensure the supply of the feed liquid.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A solid-liquid separation system of a spent fuel post-treatment process is used for separating insoluble solid impurities mixed in tetravalent uranium feed liquid, and is characterized by comprising centrifugal equipment (3), and a feed pipe (4), a discharge pipe (5) and an impurity discharge pipe (7) which are respectively connected with the centrifugal equipment (3);

the centrifugal equipment (3) is of a hollow structure;

the feeding pipe (4) is connected to the upper part of the side wall of the centrifugal equipment (3), the discharging pipe (5) extends into the centrifugal equipment (3), and the impurity discharging pipe (7) is connected to the bottom of the centrifugal equipment (3); the feeding pipe (4), the discharging pipe (5) and the impurity discharging pipe (7) are respectively provided with a control valve;

the tetravalent uranium feed liquid get into centrifugal equipment (3) by inlet pipe (4) and carry out solid-liquid centrifugal separation, the feed liquid after the separation is discharged by discharging pipe (5), solid impurity is discharged by row miscellaneous pipe (7).

2. The solid-liquid separation system of the spent fuel reprocessing process according to claim 1, wherein said feed pipe (4) is connected to the centrifugal device (3) in a tangential direction tangential to a sidewall of the centrifugal device (3).

3. The solid-liquid separation system of the spent fuel reprocessing process according to claim 1 or 2, wherein the inner side wall of the centrifugal device (3) is provided with an inclined twill structure (6), and a channel for controlling the feed liquid moving direction is formed between adjacent twills.

4. The solid-liquid separation system of the spent fuel post-treatment process according to claim 3, wherein the inclined angle between the diagonal structure (6) and the horizontal direction is 30-60 degrees, and the distance between adjacent diagonals is 5mm.

5. The spent fuel reprocessing process solid-liquid separation system according to claim 1, wherein said centrifugal device (3) comprises an integrated cylindrical section (1) and conical section (2); the conical section (2) is connected below the cylindrical section (1); solid-liquid separation is carried out in the cylindrical section (1), and solid impurities are collected in the conical section (2); the feeding pipe (4) is connected to the upper portion of the side wall of the cylindrical section (1), the discharging pipe (5) extends into the cylindrical section (1) from the top of the cylindrical section (1), and the impurity discharging pipe (7) is connected to the bottom of the conical section (2).

6. The solid-liquid separation system of the spent fuel post-treatment process according to claim 5, wherein the discharge pipe (5) is arranged at the center of the cylindrical section (1).

7. The solid-liquid separation system of the spent fuel post-treatment process according to claim 6, wherein the discharge pipe (5) is arranged at the third point of the diameter of the cylindrical section (1).

8. The solid-liquid separation system of the spent fuel reprocessing process according to claim 6, wherein said tapping pipe (5) extends to a position half the height of the cylindrical section (1).

9. The spent fuel reprocessing process solid-liquid separation system according to claim 1, wherein a bypass pipe is further connected between the feed pipe (4) and the discharge pipe (5), and the bypass pipe is connected in parallel with the centrifugal device (3); the bypass pipe is provided with a bypass valve (10).

10. The solid-liquid separation system of the spent fuel post-treatment process according to claim 1, wherein the centrifugal device (3) is further connected with a back-flushing air inlet pipe and a back-flushing exhaust pipe for back-flushing and anti-blocking of the solid-liquid separation system; and a blowback air inlet valve (13) is arranged on the blowback air inlet pipe, and a blowback exhaust valve (14) is arranged on the blowback exhaust pipe.

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