CN118335375A - System and method for drying radioactive residual liquid - Google Patents

Abstract

The present invention discloses a system and method for drying radioactive evaporative residues, the system comprising: a high-integrity container for containing radioactive evaporative residues; a condenser connected to the high-integrity container for condensation; a gas-liquid separator connected to the condenser for gas-liquid separation of materials condensed by the condenser; a vacuum pump connected to the gas-liquid separator for extracting steam and non-condensable gas inside the high-integrity container to maintain drying pressure; a gas heater connected to the vacuum pump and the high-integrity container, respectively, for heating the non-condensable gas entering the high-integrity container. The present invention allows the drying process to be carried out at a relatively low temperature, which can be tolerated by the high-integrity container, and directly dries and reduces the volume of the radioactive evaporative residues in the high-integrity container, so that the space inside the high-integrity container is maximized, avoiding complex operations during drying, temporary storage and packaging.

Description

System and method for drying radioactive residual liquid

Technical Field

The invention belongs to the technical field of radioactive treatment, and in particular relates to a system and a method for drying radioactive evaporative residue.

Background technique

During the operation of nuclear facilities, a large amount of evaporative residues are generated. After being dried into salt cakes, these evaporative residues usually need to be packed into high-integrity containers to meet storage or disposal requirements.

The existing evaporation and drying process has a high temperature, which the high-integrity container cannot withstand. Usually, the salt cake waste is formed and temporarily stored in a cylindrical steel drum, which needs to be stacked and grouted when placed in the high-integrity container. Since the cylindrical geometry of the steel drum cannot completely fit the internal space of the high-integrity cuboid, a large amount of space inside the high-integrity container is wasted and needs to be filled with cement, resulting in a large overall capacity increase, which is not conducive to the minimization of radioactive waste and radiation protection design.

Summary of the invention

The technical problem to be solved by the present invention is to provide a system and method for drying radioactive evaporative residues in view of the above-mentioned deficiencies in the prior art, so that the volume increase during the drying, temporary storage and packaging of the evaporative residues is small and the level of radioactive waste minimization is high.

The technical solution adopted to solve the technical problem of the present invention is to provide a system for drying radioactive evaporative residues, comprising:

High integrity containers for holding radioactive evaporative residues;

A condenser connected to the high integrity container, the condenser is used for condensation;

A gas-liquid separator is connected to the condenser, and is used to separate gas and liquid from the material condensed by the condenser;

A vacuum pump connected to the gas-liquid separator is used to extract the steam and non-condensable gas inside the high-integrity container to maintain the drying pressure;

The gas heater is connected to the vacuum pump and the high-integrity container respectively, and is used to heat the non-condensable gas entering the high-integrity container.

Preferably, the system for drying radioactive residual liquid further comprises:

The entrainment filter is connected to the high-integrity container and the condenser respectively, and is used for filtering entrainment of steam evaporated from the high-integrity container.

Preferably, the system for drying radioactive residual liquid further comprises:

The gas distributor is arranged in the high-integrity container and is connected to the gas heater. The gas distributor is used to distribute the non-condensable gas introduced into the high-integrity container.

Preferably, the system for drying radioactive residual liquid further comprises:

The auxiliary heating device is connected to the high-integrity container and is used to heat the radioactive residual liquid in the high-integrity container.

Preferably, the auxiliary heating device is an infrared generating device or a microwave generating device.

Preferably, the number of auxiliary heating devices is 1 to 8, and the power of each auxiliary heating device is 0.5 to 3 kW.

Preferably, the high integrity container is made of ductile iron.

The present invention also provides a method for drying radioactive evaporative residue using the above system, comprising the following steps:

The radioactive evaporative residue in the high integrity container is heated so that the temperature of the radioactive evaporative residue is 40 to 80°C.

Preferably, the high integrity container is evacuated. In the initial stage of drying, the radioactive evaporation residue to be dried contains more free water, and the system is operated under high vacuum conditions, with a vacuum degree of 60 kPa to 95 kPa;

At the end of drying, the dried evaporation residue has formed a salt cake and contains less free water, which is not enough to boil and can only evaporate naturally. The operating system runs under low vacuum conditions, with a vacuum degree of 0kPa to 60kPa.

Preferably, the steam and non-condensable gas flowing out of the high-integrity container are condensed by a condenser and cooled to 5-15° C.;

The non-condensable gas is heated to 40-80°C by a gas heater.

The system and method for drying radioactive evaporative liquid in the present invention allow the drying process to be carried out at a relatively low temperature, which can be tolerated by a high-integrity container. At the same time, the radioactive evaporative liquid is directly dried and reduced in volume in the high-integrity container, so that the space inside the high-integrity container is maximized, and the complicated operation of the evaporative liquid during drying, temporary storage and packaging is avoided. The radioactive waste minimization level is high, and the subsequent overall volume increase of the high-integrity container is small, which is conducive to the minimization of radioactive waste and radiation protection design.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a system for drying radioactive residual liquid in Example 2 of the present invention.

In the figure: 1-high integrity container; 2-auxiliary heating device; 3-gas distributor; 4-mist filter; 5-condenser; 6-gas-liquid separator; 7-vacuum pump; 8-gas heater.

Detailed ways

In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

In the description of this patent, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this patent and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this patent.

In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

The present invention provides a high-integrity container for the treatment, storage and disposal of radioactive solid waste, comprising: a high-integrity container body and a high-integrity container top cover, wherein the high-integrity container top cover is arranged on the top opening of the high-integrity container body, and the high-integrity container body is used to contain radioactive residual liquid. The high-integrity container top cover can fit well with the top opening of the high-integrity container body to form a seal. The high-integrity container body is a box-shaped structure, and the high-integrity container top cover includes a storage inner cover, a process inner cover and an outer cover that can be sealed and connected by bolts. A lifting groove is provided on the side of the high-integrity container body, and a loading and unloading groove is provided on the bottom. The high-integrity container is used for the treatment, storage and disposal of radioactive solid waste. The upper opening of the high-integrity container body is used for the containing and treatment of radioactive waste (combined with the process inner cover).

The high-integrity container is connected to the radioactive waste treatment equipment, automatic capping equipment, and automatic lifting equipment to achieve fully automated operation.

The high integrity container top cover is connected to the high integrity container body by bolts. The high integrity container top cover has the functions of sealing, material inlet and outlet, air flow distribution, auxiliary heat supply, and important process parameter measurement.

Example 1

This embodiment provides a system for drying radioactive residual liquid, including:

High integrity containers for holding radioactive evaporative residues;

A condenser connected to the high integrity container, the condenser is used for condensation;

A gas-liquid separator is connected to the condenser, and is used to separate gas and liquid from the material condensed by the condenser;

A vacuum pump connected to the gas-liquid separator is used to extract the steam and non-condensable gas inside the high-integrity container to maintain the drying pressure;

The gas heater is connected to the vacuum pump and the high-integrity container respectively, and is used to heat the non-condensable gas entering the high-integrity container.

The system and method for drying radioactive evaporative residues in this embodiment allow the drying process to be carried out at a relatively low temperature, which can be tolerated by high-integrity containers. At the same time, the radioactive evaporative residues are dried and reduced in volume directly in the high-integrity container, so that the space inside the high-integrity container is maximized, and the complicated operation of the evaporative residues during drying, temporary storage and packaging is avoided. The radioactive waste minimization level is high, and the subsequent overall volume increase of the high-integrity container is small, which is conducive to the minimization of radioactive waste and radiation protection design.

Example 2

As shown in FIG1 , this embodiment provides a system for drying radioactive evaporative residues, comprising:

High integrity container 1, used to contain radioactive evaporative residual liquid;

A condenser 5 connected to the high integrity container 1, and the condenser 5 is used for condensation;

A gas-liquid separator 6 is connected to the condenser 5 and is used to separate the gas and liquid of the material condensed by the condenser 5;

A vacuum pump 7 is connected to the gas-liquid separator 6. The vacuum pump 7 is used to extract the steam and non-condensable gas inside the high-integrity container 1 to maintain the drying pressure, and the non-condensable gas is pumped back into the high-integrity container 1 to form a cycle;

The gas heater 8 is connected to the vacuum pump 7 and the high integrity container 1 respectively. The gas heater 8 is used to heat the non-condensable gas entering the high integrity container 1 to improve its drying capacity.

The high integrity container 1 is usually filled with waste that needs to be disposed of, such as a dried salt cake of the residual liquid. The system in this embodiment directly disposes radioactive solids in the high integrity container 1 and directly dries radioactive residual liquid in the high integrity container 1.

Specifically, the condenser 5 is used to condense and cool the steam and non-condensable gas mixture to form dry non-condensable gas and condensed water.

The non-condensable gas and condensed water are separated in the gas-liquid separator 6, the condensed water is discharged from the drain port of the gas-liquid separator 6, and the non-condensable gas enters the vacuum pump 7. Specifically, the gas-liquid separator 6 in this embodiment is a gas-liquid separation tank.

The vacuum pump 7 is used to suck the steam and non-condensable gas in the high integrity container 1, the mist filter 4, the condenser 5, and the gas-liquid separator 6.

The gas heater 8 heats the radioactive residual liquid in the high integrity container 1 indirectly by heating the non-condensable gas.

Preferably, the system for drying radioactive residual liquid further comprises:

The mist filter 4 is connected to the high-integrity container 1 and the condenser 5 respectively. The mist filter 4 is used to filter the mist of the steam evaporated from the high-integrity container 1.

Preferably, the system for drying radioactive residual liquid further comprises:

The gas distributor 3 is disposed in the high-integrity container 1 . The gas distributor 3 is connected to the gas heater 8 . The gas distributor 3 is used to distribute the non-condensable gas introduced into the high-integrity container 1 .

The non-condensable gas flows through the gas distributor 3 to various gas phase spaces inside the high integrity container 1 and then reaches the steam discharge port.

Preferably, the system for drying radioactive residual liquid further comprises:

The auxiliary heating device 2 is connected to the high-integrity container 1 , and is used to directly heat the radioactive residual liquid in the high-integrity container 1 .

The cooperation of the gas heater 8 and the auxiliary heating device 2 maintains the temperature of the liquid in the high integrity container 1 at 40-70°C.

Preferably, the auxiliary heating device 2 is an infrared generating device or a microwave generating device.

The auxiliary heating device 2 is, for example, an infrared generator or a microwave generator, which can feed energy into the high-integrity container 1 to heat the radioactive residual liquid.

Preferably, the number of the auxiliary heating devices 2 is 1 to 8, and the power of each is 0.5 to 3 kW. Specifically, according to the size of the top opening of the high-integrity container 1, 1 to 8 microwave generating devices or infrared generating devices can be arranged. The auxiliary heating device 2 is arranged on the top cover of the high-integrity container 1.

Preferably, the high integrity container 1 is made of ductile iron.

The top cover of the high-integrity container is provided with a feed port and a steam discharge port, and the top cover of the high-integrity container is also provided with an auxiliary heating device 2 and a gas distributor 3. The radioactive concentrated liquid or radioactive residual liquid enters the high-integrity container 1 from the feed port, and evaporates and dries therein to generate steam. The non-condensable gas can pass through the gas phase space inside the high-integrity container 1 as much as possible through the gas distributor 3, and is discharged from the steam discharge port along with the steam.

A mist filter 4 is provided on the pipeline of the steam discharge port of the top cover of the high integrity container to intercept the droplets entrained by the steam and the non-condensable gas.

The vacuum pump 7 transports the non-condensable gas through the gas heater 8 and then returns to the high integrity container 1 to form a cycle. The non-condensable gas can also be sent to the ventilation system to increase the negative pressure in the system.

The radioactive residual liquid enters the high-integrity container 1 from the feed port and evaporates to produce water vapor. The water vapor is entrained by the non-condensable gas sent from the gas heater 8 and leaves the high-integrity container 1 from the steam discharge port. The steam and non-condensable mixture is condensed and cooled in the condenser 5 to form dry non-condensable gas and condensed water. The non-condensable gas and condensed water are separated in the gas-liquid separator 6, and the condensed water is discharged from the drain port of the gas-liquid separator 6, and the non-condensable gas enters the vacuum pump 7. The vacuum pump 7 transports the non-condensable gas through the gas heater 8 and returns to the high-integrity container 1 to form a cycle. The non-condensable gas can also be sent to the ventilation system to increase the negative pressure in the system.

A gas distributor 3 is provided on the top cover of the high integrity container. The non-condensable gas can pass through the gas distributor 3 to sweep the gas phase space inside the high integrity container 1 as much as possible, and be discharged from the steam discharge port of the high integrity container 1 along with the steam.

This embodiment also provides a method for drying radioactive residual liquid using the above system, comprising the following steps:

The radioactive residual liquid in the high integrity container 1 is heated so that the temperature of the radioactive residual liquid is 40-80°C.

Preferably, the high integrity container 1 is evacuated. In the initial stage of drying, the radioactive residual liquid to be dried contains more free water. The system is operated under high vacuum conditions, and the vacuum degree is 60 kPa to 95 kPa.

At the end of drying, the dried evaporation residue has formed a salt cake and contains less free water, which is not enough to boil and can only evaporate naturally. The operating system runs under low vacuum conditions, with a vacuum degree of 0kPa to 60kPa.

The vacuum degree can lower the boiling point of the residual liquid and make the evaporation process easier.

Preferably, the steam and non-condensable gas flowing out of the high integrity container 1 are condensed by the condenser 5 and cooled to 5-15° C.;

The non-condensable gas is heated to 40-80° C. by the gas heater 8. The secondary steam and the non-condensable gas are first condensed and cooled at low temperature, so that the non-condensable gas can have a strong water absorption and drying ability at a relatively low temperature (40-80° C.).

Specifically, the method for drying radioactive evaporative residue using the above system comprises the following steps:

In the initial stage of drying, the radioactive evaporative residue to be dried contains a large amount of free water, and the system operates under high vacuum conditions (60kPa ~ 95kPa). After the radioactive evaporative residue enters the high integrity container 1 from the feed port, it boils and evaporates to produce water vapor and a very small amount of non-condensable gas. The water vapor is condensed and cooled in the condenser 5 to form dry non-condensable gas and condensed water. The non-condensable gas and condensed water are separated in the gas-liquid separator 6, and the condensed water is discharged from the drain port of the gas-liquid separator 6. The non-condensable gas enters the vacuum pump 7. By configuring the valve switch state, the vacuum pump 7 sends the non-condensable gas to the downstream ventilation system, and the non-condensable gas is discharged from the system to increase the negative pressure.

At the end of drying, the dried residual liquid has formed a salt cake and contains less free water, which is not enough to boil and can only evaporate naturally. The operating system operates under low vacuum conditions (0kPa~60kPa). The water in the salt cake in the high-integrity container 1 evaporates to produce water vapor and a very small amount of non-condensable gas. The water vapor is entrained by a large amount of non-condensable gas sent from the gas heater 8 and leaves the high-integrity container 1 from the steam discharge port. The steam and non-condensable mixture is condensed and cooled in the condenser 5 to form dry non-condensable gas and condensed water. The non-condensable gas and condensed water are separated in the gas-liquid separator 6, and the condensed water is discharged from the drain port of the gas-liquid separator 6, and the non-condensable gas enters the vacuum pump 7. By configuring the valve switch state, the vacuum pump 7 transports the non-condensable gas through the gas heater 8, heats it to the set temperature (40~80℃), and then enters the high-integrity container 1. The medium temperature (40-80°C) non-condensable gas is dispersed and flows in the high integrity container 1 under the action of the gas distributor 3, accelerating the material drying process, entraining the moisture generated by evaporation, and leaving the high integrity container 1 from the steam discharge port of the high integrity container 1 to enter the next cycle.

The system and method for drying radioactive evaporative residues in this embodiment allow the drying process to be carried out at a relatively low temperature, which can be tolerated by the high-integrity container 1. At the same time, the radioactive evaporative residues are dried and reduced in volume directly in the high-integrity container 1, so that the space inside the high-integrity container 1 is maximized, and the complicated operation of the evaporative residues during drying, temporary storage and packaging is avoided, and the level of radioactive waste minimization is high, so that the subsequent overall volume increase of the high-integrity container 1 is relatively small, which is conducive to the minimization of radioactive waste and radiation protection design.

It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims (10)

1. A system for drying a radioactive residual liquid, comprising:

A high integrity vessel for holding a radioactive residual liquid;

the condenser is connected with the high-integrity container and is used for condensing;

The gas-liquid separator is connected with the condenser and is used for separating gas from liquid of materials condensed by the condenser;

the vacuum pump is connected with the gas-liquid separator and is used for pumping out steam and noncondensable gas in the high-integrity container and maintaining the drying pressure;

And the gas heater is respectively connected with the vacuum pump and the high-integrity container and is used for heating the non-condensable gas entering the high-integrity container.

2. The system for drying a radioactive residual liquid according to claim 1, further comprising:

and the mist filter is respectively connected with the high-integrity container and the condenser and is used for filtering mist from steam evaporated in the high-integrity container.

3. The system for drying a radioactive residual liquid according to claim 1, further comprising:

the gas distributor is arranged in the high-integrity container, is connected with the gas heater and is used for distributing the noncondensable gas introduced into the high-integrity container.

4. The system for drying a radioactive residual liquid according to claim 1, further comprising:

and the auxiliary heating device is connected with the high-integrity container and is used for heating the radioactive residual distillation liquid in the high-integrity container.

5. The system for drying a radioactive residual liquid according to claim 1, wherein the auxiliary heating means is an infrared generating means or a microwave generating means.

6. The system for drying a radioactive residual liquid according to claim 1, wherein the number of auxiliary heating means is 1 to 8 and each power is 0.5 to 3kW.

7. The system for drying a radioactive residual liquid according to claim 1, wherein the material of the high-integrity container is ductile iron.

8. A method of drying a radioactive residual liquid using the system of any one of claims 1 to 7, comprising the steps of:

The radioactive residual liquid in the high-integrity container is heated to 40-80 ℃.

9. The method for drying radioactive residual liquid according to claim 8, wherein the high-integrity container is vacuumized, the dried radioactive residual liquid contains more free moisture in the initial drying stage, and the system is operated under the high-vacuum condition, and the vacuum degree is 60kPa to 95kPa;

at the end of drying, the dried raffinate has formed a salt cake and contains less free moisture, is insufficient for boiling to occur, is only naturally evaporated, and the operating system is operated at a low vacuum level of 0kPa to 60kPa.

10. The method for drying radioactive residual liquid according to claim 8, wherein the steam and non-condensable gas flowing out of the high-integrity container are condensed by a condenser, and the condensed and cooled to 5-15 ℃;

the noncondensable gas is heated to 40-80 ℃ by a gas heater.