Radioactive waste liquid treatment methods and systems

Abstract

This invention discloses a method for treating radioactive waste liquid. The method includes: continuously feeding radioactive waste liquid into an evaporator, where the waste liquid circulates between a heating device and a separation device; wherein the heating device heats the radioactive waste liquid to bring it to a boil, and the boiling waste liquid undergoes vapor-liquid separation in the separation device to generate secondary steam, thereby concentrating the radioactive waste liquid; the secondary steam generated from the evaporation of the radioactive waste liquid is introduced into a steam compression device, where it is compressed and heated before being sent to the heating device as a primary heat source for heat exchange with the radioactive waste liquid; and the concentrated radioactive waste liquid is continuously discharged from the evaporator, with the discharge flow rate controlled to ensure that the radioactive waste liquid is concentrated to a predetermined multiple. Furthermore, this invention also provides a radioactive waste liquid treatment system.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of radioactive waste treatment technology, specifically to a method and system for treating radioactive waste liquid. Background Technology

[0002] Currently, the treatment of radioactive waste liquid usually uses evaporation concentration technology. This technology mainly involves sending preheated radioactive waste liquid into an evaporator, using high-temperature steam to heat the radioactive waste liquid in the evaporator, so that the radioactive waste liquid is evaporated and separated into steam and concentrate. The steam can be directly discharged after condensation, while the concentrate needs further treatment.

[0003] However, traditional evaporation and concentration technologies mostly employ dedicated heat sources, requiring a continuous input of new steam to heat the feed liquid, resulting in high energy consumption. Furthermore, the large amount of secondary steam generated within the evaporator is directly condensed using cooling water, which prevents heat recovery and consumes cooling water. Summary of the Invention

[0004] An embodiment of the present invention provides a method for treating radioactive waste liquid. The method includes: continuously feeding radioactive waste liquid into an evaporator, the evaporator including a heating device and a separation device, the radioactive waste liquid circulating between the heating device and the separation device; wherein, the heating device heats the radioactive waste liquid to bring it to a boil, the boiling radioactive waste liquid undergoes vapor-liquid separation in the separation device to generate secondary steam, thereby concentrating the radioactive waste liquid; the secondary steam generated by the evaporation of the radioactive waste liquid is introduced into a steam compression device, the secondary steam is compressed and heated by the steam compression device, and then transported to the heating device as a first heat source for heat exchange with the radioactive waste liquid; continuously discharging the concentrated radioactive waste liquid from the evaporator, and controlling the discharge flow rate of the concentrated radioactive waste liquid to ensure that the radioactive waste liquid is concentrated to a predetermined multiple.

[0005] Embodiments of the present invention also provide a radioactive waste liquid treatment system. The system includes: an evaporator for evaporating and concentrating radioactive waste liquid; the evaporator includes: a heating device having a heating chamber for providing a flow channel for heating steam, and a liquid flow channel for the radioactive waste liquid to flow within the heating chamber, wherein the heating steam can exchange heat with the radioactive waste liquid to heat the radioactive waste liquid; a separation device connected to the liquid flow channel of the heating device for vapor-liquid separation of the boiled radioactive waste liquid after heat treatment to form secondary steam, thereby concentrating the radioactive waste liquid; a circulation pipeline connected to both the separation device and the heating device, providing a channel for the radioactive waste liquid to circulate between the heating device and the separation device; a steam compression device disposed between the inlet of the separation device and the heating chamber, used to compress and heat the secondary steam and serve as the first heat source for the heating device; and a residual liquid storage container connected to the heating device for receiving and storing the residual liquid formed after the radioactive waste liquid has been concentrated through evaporation; wherein a drain valve is provided between the residual liquid storage container and the heating device to control the discharge flow rate of the residual liquid.

[0006] The method and system described in this embodiment can recover and utilize the heat energy of the secondary steam generated by the evaporation of radioactive waste liquid, reduce the amount of cooling water used, and greatly reduce the energy consumption in the evaporation treatment process of radioactive waste liquid. Attached Figure Description

[0007] Other objects and advantages of the invention will become apparent from the following description of embodiments of the invention with reference to the accompanying drawings, and will help to provide a comprehensive understanding of the invention.

[0008] Figure 1 This is a schematic diagram of a radioactive waste liquid treatment system according to an embodiment of the present invention.

[0009] Figure 2 This is a schematic diagram of the structure of a separation device according to an embodiment of the present invention.

[0010] Figure 3 This is a schematic diagram of a purification device according to an embodiment of the present invention.

[0011] Figure 4 This is a schematic diagram of a sampling device according to an embodiment of the present invention.

[0012] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only one embodiment of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0014] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application should have the ordinary meaning understood by a person with ordinary skill in the art to which this application pertains. Where the terms "first," "second," etc., are used throughout the text, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data described by "first," "second," etc., can be interchanged where appropriate. Where "and / or" appears throughout the text, it means including three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. Furthermore, for ease of description, spatial relative terms such as "above," "below," "top," "bottom," etc., may be used here, only to describe the spatial positional relationship between one device or feature as shown in the figure and other devices or features. It should be understood that this also includes different orientations in use or operation besides those shown in the figure.

[0015] During the operation, decontamination, and decommissioning of nuclear industrial facilities, a large amount of radioactive waste liquid is inevitably generated. Due to the large volume of radioactive waste liquid generated, especially intermediate and low-level radioactive waste liquid, it is necessary to treat it to reduce its volume and facilitate solidification. In this embodiment of the invention, the radioactive waste liquid is evaporated. The water vapor formed by the evaporation of the radioactive waste liquid has reduced radioactivity intensity and can be directly discharged after condensation and cooling. The volume of the remaining concentrated liquid after evaporation is greatly reduced, and after solidification treatment, it is stored, thereby reducing the storage volume of the radioactive waste liquid and facilitating subsequent transportation.

[0016] Figure 1 A schematic diagram of a radioactive waste treatment system according to an embodiment of the present invention is shown. Figure 1As shown, the radioactive waste liquid treatment system in this embodiment of the invention includes an evaporator, a vapor compression device 20, and a residual vapor storage container 42. The evaporator heats the radioactive waste liquid to boil and evaporate it into steam, which is then concentrated to form residual vapor. The vapor compression device 20 is connected to the evaporator and compresses and heats the steam formed by the evaporation of the radioactive waste liquid in the evaporator to form heating steam. This heating steam is then transported to the evaporator to exchange heat with the radioactive waste liquid within the evaporator, serving as the primary heat source for the evaporation of the radioactive waste liquid. The residual vapor storage container 42 is connected to the evaporator and is used to receive and store the residual vapor formed after the radioactive waste liquid in the evaporator has been concentrated.

[0017] like Figure 1 As shown, the evaporator in this embodiment is a split-type evaporator, which includes a heating device 11 and a separation device 12. The heating device 11 has a heating chamber with a liquid flow channel inside. The liquid flow channel is used for the flow of radioactive waste liquid, and the high-temperature gas flowing in the heating chamber can exchange heat with the radioactive waste liquid in the liquid flow channel to heat the radioactive waste liquid. The separation device 12 is connected to the liquid flow channel of the heating device 11 and is used to perform vapor-liquid separation on the boiling radioactive waste liquid, thereby concentrating the radioactive waste liquid.

[0018] Furthermore, a circulation pipe is provided between the liquid flow channel of the heating device 11 and the separation device 12 to provide a channel for the circulation of radioactive waste liquid between the heating device 11 and the separation device 12. Specifically, the separation device 12 is located above the heating device 11. The heating device 11 has an inlet at its bottom and an outlet at its top. The separation device 12 has an outlet at its bottom and an inlet on its side wall. The circulation pipe includes a first circulation pipe 13 and a second circulation pipe 14. The first circulation pipe 13 connects the inlet at the bottom of the heating device 11 and the outlet at the bottom of the separation device 12. The second circulation pipe 14 connects the outlet at the top of the heating device 11 and the inlet on the side wall of the separation device 12, thereby allowing the radioactive waste liquid in the separation device 12 to flow downwards into the heating device 11, and the radioactive waste liquid in the heating device 11 to flow upwards into the separation device 12, forming a circulation.

[0019] In some embodiments, the separation device 12 is disposed above the heating device 11, and the radioactive waste liquid can circulate between the heating device 11 and the separation device 12 by relying on its own sealing difference. Specifically, after the radioactive waste liquid is heated to boiling in the heating device 11, it flows upward into the separation device 12 due to the decrease in density, while the radioactive waste liquid in the separation device 12 increases in density due to evaporation and concentration, and can flow downward into the heating device 11, thereby forming a natural circulation between the heating device 11 and the separation device 12, ensuring the continuity of the dynamic circulation of the radioactive waste liquid.

[0020] In some embodiments, a circulation pump 82 is provided on the first circulation pipe 13 to control the forced circulation of radioactive waste liquid between the heating device 11 and the separation device 12. Compared with natural circulation, this can increase the amount of radioactive waste liquid that the evaporator can process and the heat transfer efficiency, thereby improving the treatment efficiency of the radioactive waste liquid.

[0021] It should be noted that the evaporator in this embodiment is equipped with a working liquid level. After the material is fed into the evaporator to the working liquid level, heating and circulation begin. Furthermore, during normal operation of the radioactive waste treatment system, the radioactive waste liquid in the evaporator also needs to be maintained at the working liquid level. In this embodiment, the inlet of the separation device 12 is located at the working liquid level of the evaporator.

[0022] In some embodiments, the evaporator's discharge port is located on the first circulation pipe 13, between the circulation pump 82 and the heating device 11. A discharge pipe 103 connects the residual evaporation liquid storage container 42 and the discharge port. The residual evaporation liquid formed by evaporation and concentration in the evaporator is discharged through the discharge pipe 103 into the residual evaporation liquid storage container 42 for storage, facilitating subsequent processing. Furthermore, a discharge valve can be installed on the discharge pipe 103 to control the evaporator's discharge rate.

[0023] In some embodiments, the feed inlet of the evaporator may also be located on the first circulation pipe 13, between the circulation pump 82 and the separation device 12, and above the bottom of the heating device 11. In this embodiment, the discharge speed is kept constant by controlling the discharge valve, while the feed speed of the radioactive waste liquid into the evaporator is kept constant, so that continuous feeding and discharging can be maintained, and the operation of the entire treatment system can be kept stable.

[0024] like Figure 1 As shown, the processing system in this embodiment also includes a feeding device 41, which is connected to the inlet of the evaporator and is used to store the radioactive waste liquid to be treated. The radioactive waste liquid in the feeding device 41 can be fed into the evaporator for evaporation treatment. Specifically, a feed pipe 101 is connected between the feeding device 41 and the first circulation pipe 13. A feed pump 81 is installed on the feed pipe 101, which can transport the radioactive waste liquid in the feeding device 41 sequentially through the feed pipe 101 and the first circulation pipe 13 into the evaporator.

[0025] In addition, the processing system also includes a return pipe 102, one end of which is connected to the feeding device 41 and the other end to the feed pipe 101. At least a portion of the radioactive waste liquid in the feed pipe 101 can be returned to the feeding device 41 via the return pipe 102. In this embodiment, a return valve is provided on the return pipe 102. The flow rate of the radioactive waste liquid in the return pipe 102 can be controlled by adjusting the return valve, thereby controlling the feed flow rate of the radioactive waste liquid into the evaporator, thus preventing pressure fluctuations in the radioactive waste liquid in the feed pipe 101 and ensuring a stable feed of the radioactive waste liquid.

[0026] Furthermore, the inlet of the vapor compressor 20 is connected to the separator 12, and the outlet of the vapor compressor 20 is connected to the heating chamber of the heating device 11. The boiled radioactive waste liquid, after heat treatment, evaporates in the separator 12 to form secondary steam. The secondary steam is discharged from the top of the separator 12 to the vapor compressor 20, where it is compressed and heated to form heating steam. The heating steam is then transported to the heating chamber of the heating device 11 to exchange heat with the radioactive waste liquid in the liquid flow channel of the heating device 11, thereby achieving the heat treatment of the radioactive waste liquid.

[0027] In this embodiment, a vapor compression device 20 is used to recover the latent heat of the secondary steam generated during the evaporation of radioactive waste liquid. This allows the pressurized and heated secondary steam to be used as a heat source to heat the subsequent feed radioactive waste liquid, eliminating the need for a dedicated boiler room for heating and reducing energy consumption during the evaporation treatment of radioactive waste liquid.

[0028] like Figure 1 As shown, the radioactive waste liquid treatment system in this embodiment also includes a steam generator 30. The steam generator 30 can generate high-temperature steam and is connected to the evaporator, thereby providing a second heat source for heating the radioactive waste liquid in the evaporator. The steam generator 30 can serve as a heat source for the evaporator during the start-up of the treatment system, and can also provide supplementary steam to the evaporator during normal operation of the treatment system to compensate for heat loss.

[0029] Specifically, the steam generator 30 has a water-containing cavity and an electric heating element inside, which heats the water in the cavity to form high-temperature steam. In this embodiment, the steam generator 30 is connected to the heating cavity of the heating device 11, thereby providing a heat source for the heating device 11 to heat the radioactive waste liquid. The high-temperature steam generated by the steam generator 30 enters the heating cavity of the heating device 11 and exchanges heat with the radioactive waste liquid, causing the radioactive waste liquid to boil. In addition, the steam generated by the steam generator 30 and the pressurized and heated secondary steam exchange heat in the heating device 11 to form a condensate with a certain temperature, which then flows back into the steam generator 30, thereby keeping the liquid level in the steam generator 30 stable.

[0030] In some embodiments, the steam generated by the steam generator 30 can be delivered to the inlet of the steam compressor 20 to prevent surge in the steam compressor 20. Compared to the conventional method of circulating superheated steam from the outlet of the steam compressor 20 to the inlet of the steam compressor 20, in this embodiment, high-temperature and high-pressure heating steam is delivered to the heating device 11 for heat exchange before entering the steam generator 30. This allows the steam in the steam generator 30 to enter the steam compressor 20 from the inlet, thus avoiding excessively high inlet temperature of the steam compressor 20.

[0031] like Figure 1 As shown, the processing system also includes a preheating device. The evaporator is connected to the preheating device. When evaporating radioactive waste liquid, the preheating device is used to preheat the radioactive waste liquid before it is conveyed to the evaporator. In this embodiment, the preheating device includes a first preheating device 51, which is disposed between the feeding device 41 and the evaporator for preheating the radioactive waste liquid. In this embodiment, the radioactive waste liquid is preheated in the first preheating device 51 before being conveyed to the evaporator. Specifically, the first preheating device 51 can be a heat exchanger. The first preheating device 51 is also connected to a steam generator 30, which provides a heat source for the first preheating device 51.

[0032] In this embodiment, the radioactive waste liquid is transported to the tube side of the first preheating device 51, and the hot water generated by the electric heating unit in the steam generator 30 is transported to the first preheating device 51 to exchange heat with the radioactive waste liquid, thereby preheating the radioactive waste liquid at room temperature, reducing the temperature difference between the radioactive waste liquid and the phase transition temperature, and improving the efficiency of radioactive waste liquid treatment.

[0033] Furthermore, the processing system in this embodiment may also include a condensate storage container 43 connected to the first preheating device 51, for receiving and storing the condensate in the first preheating device 51 whose temperature has decreased after heat exchange with the radioactive waste liquid. In some embodiments, the processing system may not include a condensate storage container 43, and the condensate formed after heat exchange in the first preheating device 51 may be directly discharged.

[0034] In some embodiments, a cooling device is also provided on the condensate discharge pipe of the first preheating device 51. When the temperature of the condensate flowing out of the first preheating device 51 is high, the cooling device can cool and lower the temperature of the condensate before it is discharged. In this embodiment, the cooling device can be a heat exchanger, and cooling water serves as the cold source of the cooling device, used to exchange heat with the condensate to lower its temperature.

[0035] In some embodiments, the preheating device further includes a second preheating device 52, which is disposed between the first preheating device 51 and the evaporator. The second preheating device 52 is used to preheat the radioactive waste liquid again, so that the temperature of the radioactive waste liquid is raised to near the boiling point (e.g., 98°C) before being fed into the evaporator, thereby improving the evaporation and separation efficiency of the radioactive waste liquid.

[0036] In this embodiment, the radioactive waste liquid, after initial preheating, is transported to the tube side of the second preheating device 52, while steam is transported to the shell side of the second preheating device 52 to exchange heat with the radioactive waste liquid, thereby achieving reheating of the radioactive waste liquid, further increasing its temperature and improving treatment efficiency. The second preheating device 52 is connected to the steam generator 30. After heat exchange between the steam and the radioactive waste liquid, condensate is formed and flows into the steam generator 30 to replenish the water level within it.

[0037] It should be noted that during the startup phase, the steam used for preheating in the second preheating device 52 can be steam generated by the steam generator 30. The shell side of the second preheating device 52 is also connected to the heating chamber of the heating device 11. During normal operation, the steam used for preheating in the second preheating device 52 can be heating steam generated by the vapor compressor 20. This heating steam is then transported to the second preheating device 52 after passing through the heating chamber of the heating device 11, where it exchanges heat with the radioactive waste liquid. Furthermore, during normal operation, the steam generator 30 can also provide steam to the second preheating device 52 to compensate for system heat loss.

[0038] In some embodiments, a steam trap is also provided between the second preheating device 52 and the steam generating device 30, and a steam trap (not shown in the figure) can also be provided between the heating device 11 and the steam generating device 30. The steam trap is used to separate the condensate flowing out of the second preheating device 52 and the heating device 11 into vapor and liquid, so as to prevent the condensate from carrying gas into the steam generating device 30 and affecting the normal operation of the steam generating device 30.

[0039] Before the treatment system operates, a large amount of non-condensable gas (e.g., air) exists in the equipment, and a small amount of non-condensable gas is also generated during the heating of the radioactive waste liquid during system operation. To remove non-condensable gas from the treatment system, the treatment system in this embodiment is also equipped with a non-condensable gas emission and recovery device 70. For example... Figure 1 As shown, the non-condensable gas emission and recovery device 70 is connected to the second preheating device 52 and is used to discharge the non-condensable gas in the second preheating device 52 and recover the steam discharged from the second preheating device 52, so as to avoid excessive non-condensable gas in the second preheating device 52, which would affect the heat transfer efficiency.

[0040] Specifically, the non-condensable gas emission recovery device 70 is connected to the shell side of the second preheating device 52. Cooling water is introduced into the non-condensable gas emission recovery device 70. After the gas in the shell side of the second preheating device 52 is discharged into the non-condensable gas emission recovery device 70, it exchanges heat with the cooling water inside the non-condensable gas emission recovery device 70. The vapor in the discharged gas is condensed by the cooling water to form condensate, which can be directly discharged, while the non-condensable gas is directly discharged from the non-condensable gas emission recovery device 70. It should be noted that, in this embodiment, non-condensable gas refers to gas that will not be condensed by cooling water, such as air.

[0041] In this embodiment, the non-condensable gas emission recovery device 70 is also connected to the condensate storage container 43, and the condensate formed by the condensation of vapor in the non-condensable gas emission recovery device 70 can be recovered into the condensate storage container 43. When the condensate storage container 43 is not provided, the condensate generated in the non-condensable gas emission recovery device 70 is directly discharged.

[0042] In addition, the non-condensable gas emission and recovery device 70 in this embodiment can also be connected to the heating device 11 to discharge non-condensable gas in the heating chamber of the heating device 11 and recover the steam discharged by the heating device 11, so as to avoid excessive non-condensable gas in the heating device 11 and affect the heat exchange efficiency.

[0043] In some embodiments, the heating device 11 is provided with at least two exhaust ports. One exhaust port is connected to the second preheating device 52 for discharging the gas in the heating device 11 to the second preheating device 52, so that the steam therein exchanges heat with the radioactive waste liquid in the second preheating device 52; the other exhaust port is connected to the non-condensable gas emission and recovery device 70 for directly discharging the gas in the heating device 11 to the non-condensable gas emission and recovery device 70, so as to directly discharge the non-condensable gas in the heating device 11.

[0044] In addition, at least two exhaust ports are provided at different heights of the heating device 11 and are connected to exhaust valves respectively to discharge gas from different locations inside the heating device 11, thereby removing non-condensable gas.

[0045] Similarly, the second preheating device 52 is provided with at least two exhaust ports, which are located at different heights of the second preheating device 52 and are respectively connected to exhaust valves to discharge the gas at different locations in the second preheating device 52, thereby removing the non-condensable gas.

[0046] It should be noted that the processing system in this embodiment can be equipped with a cooling water storage container, which can store and provide cooling water. The cooling water can not only cool the condensate flowing out of the first preheating device 51, but also cool the steam in the non-condensable gas emission recovery device 70. In addition, the cooling water can also provide cooling for the oil tank and motor of the steam compression device 20, the circulating pump 82, and the mechanical seals of other pumps in the processing system.

[0047] like Figure 2 As shown, in some embodiments, the separation device 12 is equipped with a first demister 121 to remove radioactive waste liquid carried in the secondary steam generated by the evaporation of radioactive waste liquid, preventing the secondary steam from carrying droplets into the steam compression device and causing contamination. Specifically, the first demister 121 can be located at the top of the separation device 12, above the working liquid level of the evaporator.

[0048] In some embodiments, the first demister 121 includes a corrugated plate demister 1211, which comprises a plurality of corrugated plates arranged along the axial direction of the separation device 12, with gaps between the corrugated plates. When the secondary steam formed by the evaporation of radioactive waste liquid flows through the corrugated plate demister 1211, the secondary steam can flow out through the gaps between the corrugated plates. The droplets carried in the secondary steam collide with the corrugated plates at the bends and adhere to the surface of the corrugated plates, thereby defoaming the secondary steam and achieving initial purification of the secondary steam.

[0049] In some embodiments, the first demister 121 includes a wire mesh demister 1212, which is made of metal wire mesh. When the secondary steam formed by the evaporation of radioactive waste liquid flows through the wire mesh demister 1212, the droplets carried by the secondary steam are resisted and adhere to the metal wire, thereby playing the role of separating droplets and realizing the initial purification of the secondary steam.

[0050] Optionally, one of the corrugated plate demister 1211 and the wire mesh demister 1212 can be installed in the separation device 12. Alternatively, both the corrugated plate demister 1211 and the wire mesh demister 1212 can be installed in the separation device 12. The wire mesh demister 1212 can be installed below the corrugated plate demister 1211. Using two types of demisters to purify the secondary steam can greatly increase the demisting effect.

[0051] like Figure 1 As shown, the processing system in this embodiment also includes a purification device 60. The purification device 60 is connected between the separation device 12 and the steam compression device 20, and is used to purify the secondary steam formed by the evaporation of radioactive waste liquid in the separation device 12. After removing the radioactive substances mixed in the secondary steam, it is then transported to the steam compression device 20 to prevent the radioactive substances mixed in the secondary steam from causing radioactive contamination to the steam compression device 20 and the downstream steam generator 30.

[0052] Specifically, such as Figure 3 As shown, the purification device 60 is equipped with a second demister 61, which is used to demister the secondary steam entering the purification device 60, remove radioactive waste liquid mixed in the secondary steam, and achieve purification of the secondary steam. In some embodiments, the second demister 61 can be a wire mesh demister, and the liquid droplets mixed in the secondary steam can adhere to the wire mesh demister, thereby reducing the liquid mist entrained in the secondary steam.

[0053] like Figure 1 and Figure 3 As shown, a spray element 62 is also provided on the top of the purification device 60. The spray element 62 sprays inside the purification device 60 to clean the secondary steam entering the purification device 60, so that the radioactive droplets carried by the secondary steam flow down with the spray liquid, thereby removing the radioactive substances mixed in the secondary steam and achieving the purpose of purifying the secondary steam.

[0054] In some embodiments, the spray element 62 is disposed above the second demister 61. While spraying and cleaning the secondary steam, the spray element 62 can also spray and clean the second demister 61, causing radioactive droplets adhering to the second demister 61 to flow with the spray liquid to the bottom of the purification device 60. Furthermore, the spray radiation angle of the spray element 62 can be no less than 90 degrees, thereby radiating spray in all directions to cover the entire interior of the purification device 60, achieving spray cleaning of the entire demister and the inner surface of the purification device 60.

[0055] Furthermore, the bottom of the purification device 60 contains spray liquid, and the spray element 62 is connected to the drain port at the bottom of the purification device 60 through a spray liquid pump 84. The spray liquid pump 84 can transport the spray liquid at the bottom of the purification device 60 to the spray element 62, so that the spray element 62 can use the spray liquid contained in the purification device 60 to spray the secondary steam, which not only ensures the purification effect, but also realizes the recycling of the spray liquid.

[0056] like Figure 1 As shown, the purification device 60 is connected to the steam generator, which can transport the condensate in the steam generator to the purification device 60 as a spray liquid. While ensuring the purification effect, it also avoids the need to set up a special water storage tank or water source to achieve spray cleaning, thus simplifying the treatment system.

[0057] Furthermore, when the concentration of radioactive material in the spray liquid contained in the purification device 60 reaches a predetermined concentration threshold, the spray liquid needs to be replaced with new spray liquid to ensure the purification effect of the spray liquid on the secondary steam. Specifically, the spray liquid in the purification device 60 can be discharged into the radioactive waste liquid feeding device 41 to facilitate the evaporation treatment of the radioactive spray liquid. Then, the condensate in the evaporation generator 30 is transported to the purification device 60 to replenish the spray liquid used for spray cleaning.

[0058] like Figure 1 and Figure 3 As shown, the purification device 60 also includes a packing layer 63, which is located below the second demister 61 and above the surface of the spray liquid. The secondary steam entering the purification device 60 first passes through the packing layer 63, which enhances the contact and mass transfer between the secondary steam and the spray liquid, thus improving purification efficiency. Exemplarily, the packing layer 63 includes two fixed sieve plates and packing material disposed between them, thereby fixing the packing material within the purification device 60. Optionally, the packing material in this embodiment can be Pall ring packing. Due to its perforated ring walls, it greatly improves the utilization rate of the internal space and surface area of ​​the ring, resulting in low airflow resistance, uniform liquid distribution, and advantages such as high throughput, low resistance, and high separation efficiency.

[0059] In this embodiment, the air inlet of the purification device 60 is located below the packing layer 63, so that after the secondary steam enters the purification device 60, it flows sequentially through the packing layer 63, the second demister 61, and the spray element 62. Through the combined action of the packing, the demister, and the spray cleaning, the purification effect on the secondary steam is improved. In addition, the liquid level of the spray liquid contained in the purification device 60 can be higher than the air inlet, so that the secondary steam flows upward after being cleaned by the spray liquid, further improving the purification effect.

[0060] like Figure 1 As shown, the processing system in this embodiment also includes a condensate pump 83. The inlet of the condensate pump 83 is connected to the steam generator 30 to transport hot water heated to a certain temperature within the steam generator 30. Specifically, the outlet of the condensate pump 83 can be connected to the first preheating device 51 to transport the hot water from the steam generator 30 to the shell side of the first preheating device 51 for initial preheating of the radioactive waste liquid. The outlet of the condensate pump 83 can also be connected to the purification device 60 to replenish the purification device 60 with spray liquid used for spray cleaning.

[0061] In addition, a spray point is provided on the outlet pipe 104 of the steam compressor 20, and the outlet of the condensate pump 83 can also be connected to the spray point to spray and cool the superheated steam in the outlet pipe 104 of the steam compressor 20, thereby reducing the temperature of the superheated steam and converting it into saturated steam, which is convenient to be provided to the heating device 11 and the second preheating device 52 as a heat source.

[0062] like Figure 1 As shown, the processing system in this embodiment also includes a sampling device 90, which is connected to the gas path before the steam inlet of the vapor compression device 20. The sampling device 90 is used to sample the secondary steam generated by the evaporation of radioactive waste liquid, so as to detect the secondary steam and determine the purification capacity of the processing system.

[0063] like Figure 4 As shown, the sampling device 90 has a cooling chamber 91 in which coolant circulates. At least one sample flow channel 92 is provided in the cooling chamber 91. The sample flow channel 92 is connected to the gas path upstream of the vapor compression device 20 and is used to provide a channel for the flow of secondary steam to sample the secondary steam. The secondary steam in the sample flow channel 92 can be condensed by the coolant to form a liquid sample. By detecting the concentration of the liquid sample, the purification coefficient of the treatment system can be determined.

[0064] In some embodiments, the sampling device 90 is provided with at least one collection port 93, which is connected to the sample flow channel 92 and is used to collect the liquid sample formed after the secondary vapor in the sample flow channel 92 is condensed.

[0065] Specifically, the separation device 12 is provided with a first sampling port and a second sampling port. The first sampling port is located below the first demister 121, and the second sampling port is located above the first demister 121. The sample flow channel 92 includes a first sample flow channel and a second sample flow channel. The first sample flow channel is connected to the first sample port and is used to sample the secondary steam in the separation device 12 that has not undergone demisting treatment by the first demister 121. The second sample flow channel is connected to the second sample port and is used to sample the secondary steam in the separation device 12 that has undergone demisting treatment by passing through the first demister 121. In this embodiment, by sampling and detecting the secondary steam before and after the first demister 121, the purification capacity of the evaporator can be determined based on the concentration of the secondary steam.

[0066] Furthermore, the sample flow channel 92 also includes a third sample flow channel, which is connected to the outlet of the purification device 60 to sample the secondary steam at the outlet of the purification device 60. In this embodiment, the purification coefficient of the treatment system can be verified by detecting the concentration of condensate in the condensate storage container. Simultaneously, by sampling and detecting the secondary steam at the outlet of the purification device 60, the concentration of the secondary steam can be used to assist in verifying the purification coefficient and decontamination factor of the treatment system, and to determine whether the condensate storage container or its sampling port is contaminated.

[0067] The treatment system described in this embodiment can evaporate and concentrate radioactive waste liquid, thereby reducing its volume and facilitating its subsequent storage and solidification. Furthermore, this embodiment also provides a method for treating radioactive waste liquid, which can be implemented using the treatment system described in any of the above embodiments. The treatment method in this embodiment specifically includes the following steps.

[0068] In step S10, radioactive waste liquid is continuously fed into the evaporator, and the radioactive waste liquid circulates between the heating device 11 and the separation device 12. The heating device 11 heats the radioactive waste liquid to make it boil, and the boiling radioactive waste liquid undergoes vapor-liquid separation in the separation device 12 to generate secondary steam, thereby concentrating the radioactive waste liquid.

[0069] In step S20, the secondary steam generated by the evaporation of radioactive waste liquid is introduced into the steam compression device 20. After the secondary steam is compressed and heated by the steam compression device 20, it is sent to the heating device 11 as the first heat source of the heating device 11 to exchange heat with the radioactive waste liquid.

[0070] Step S30: Continuously discharge the concentrated radioactive waste liquid from the evaporator and control the discharge flow rate of the concentrated radioactive waste liquid to ensure that the radioactive waste liquid is concentrated to a predetermined multiple.

[0071] In this embodiment, the vapor compression device 20 is used to compress and heat the steam generated from the evaporation of radioactive waste liquid to form heating steam. The heating steam is used as the heat source for the evaporator, thereby recovering and utilizing the latent heat of vaporization of the radioactive waste liquid, which helps to reduce energy consumption. The steam generator 30 only serves as the heat source for the evaporator during startup and provides a small amount of compensating steam to the treatment system during normal operation to compensate for the heat loss of the treatment system and maintain stable system operation.

[0072] Furthermore, by employing the processing method described in this embodiment, the discharge flow rate can be controlled to maintain the discharged radioactive waste liquid at the required concentration factor, thereby achieving effective concentration of the radioactive waste liquid.

[0073] Specifically, the feed flow rate of the radioactive waste liquid can be controlled to maintain a predetermined feed rate, while the discharge flow rate can be controlled to maintain a predetermined discharge rate, so as to ensure that the continuously discharged radioactive waste liquid has been concentrated to a predetermined multiple. In this embodiment, by simultaneously controlling the feed flow rate and the discharge flow rate of the radioactive waste liquid, for example, by controlling both the feed flow rate and the discharge flow rate to remain constant, the liquid level in the evaporator is maintained within the working liquid level range (e.g., -50 to +50 mm), thereby ensuring that the discharged radioactive waste liquid has reached the predetermined concentration multiple.

[0074] like Figure 1 As shown, the evaporator in this embodiment is equipped with a drain pipe 103, and a drain valve is provided on the drain pipe 103. The discharge flow rate of the concentrated radioactive waste liquid can be controlled by adjusting the opening degree of the drain valve.

[0075] Optionally, the radioactive waste liquid can circulate naturally between the heating device 11 and the separation device 12 by relying on the density difference caused by temperature changes.

[0076] Optionally, a circulation pump 82 is installed on the circulation pipeline between the heating device 11 and the separation device 12. The circulation pump 82 drives the radioactive waste liquid to circulate between the heating device 11 and the separation device 12, thereby improving the processing efficiency of the evaporator. Specifically, after the radioactive waste liquid enters the evaporator, it is driven to circulate by the circulation pump 82, increasing the flow rate of the radioactive waste liquid. The radioactive waste liquid is heated to boiling in the heating device 11 and then undergoes vapor-liquid separation in the separation device 12.

[0077] In some embodiments, the radioactive waste liquid in the feeding device 41 can be continuously fed to the evaporator. During the feeding process, the flow rate of the radioactive waste liquid in the return pipe 102 can be adjusted to control the feed flow rate of the radioactive waste liquid to the heating device 11, so as to avoid excessive pressure fluctuation in the feed pipe 101.

[0078] In some embodiments, the steam generated by the steam generator 30 can also be used as a second heat source for the heating device 11 to compensate for the steam required for heating the heating device 11 and to provide a heat source for the heating device 11 when the radioactive waste treatment system is started. The steam generator 30 is the start-up heat source for the entire system. When the system starts up, the steam generator 30 operates at full power. After a large amount of secondary steam is generated in the evaporator and the steam compression device 20 is operating normally, the steam generator 30 switches to low power operation to provide compensation steam for the system and maintain stable system operation.

[0079] In some embodiments, the radioactive waste liquid in the feeding device 41 can be continuously fed to the first preheating device 51, and the condensate in the steam generator 30 can be fed to the first preheating device 51 to preheat the radioactive waste liquid, and then the preheated radioactive waste liquid can be fed to the evaporator.

[0080] Furthermore, the radioactive waste liquid preheated by the first preheating device 51 can be transported to the second preheating device 52, and the heating steam generated by the vapor compression device 20 can be transported to the heating device 11 and then to the second preheating device 52 as a heat source for the second preheating device 52 to preheat the radioactive waste liquid a second time. The radioactive waste liquid after the second preheating is then fed into the evaporator.

[0081] In this embodiment, the radioactive waste liquid enters the first preheating device 51 via the feed pump 81. The radioactive waste liquid is preheated to approximately 70°C using the condensate of the secondary steam generated from the steam generator 30 after heating the radioactive waste liquid, and then fed into the second preheating device 52. In the second preheating device 52, the radioactive waste liquid is further preheated to above 90°C using heating steam generated from the compressed secondary steam in the heating device 11.

[0082] The secondary steam is pressurized and heated by the steam compression device 20, and then sent as heating steam into the heating chamber of the heating device 11. A portion of it enters the shell side of the second preheating device 52, serving as the heat source for the evaporator and the second preheating device 52, respectively completing the evaporation and preheating process of the radioactive waste liquid. The secondary steam generated by the evaporation of the radioactive waste liquid enters the steam compression device 20 again for heating and pressurization, serving as a heat source to heat the subsequent radioactive waste liquid, forming a continuous cycle process.

[0083] In some embodiments, the condensate in the heating device 11 and the second preheating device 52 flows to the steam generator 30 by gravity to replenish the steam generator 30. The condensate is formed by the condensation of the steam in the heating device 11 and the second preheating device 52 after heat exchange with the radioactive waste liquid.

[0084] Specifically, the radioactive waste liquid is heated by the compressed and heated secondary steam and condensed into a condensate at about 112°C. The condensate flows by gravity into the steam generator 30, and most of the condensate is transported by the condensate pump 83 to the first preheating device 51 to preheat the radioactive waste liquid at room temperature. The radioactive waste liquid at room temperature can be preheated to about 70°C. After the condensate is cooled, it is transported to the condensate storage container 43 as a purified liquid.

[0085] Furthermore, a steam trap can be used to separate the condensate flowing out of the heating device 11 and / or the second preheating device 52 into vapor and liquid components, so as to prevent the gas entrained in the condensate from entering the steam generator 30.

[0086] In some embodiments, before the steam in the separator 12 leaves the separator 12, it is defoamed by a first demister 121. Alternatively, a purification device 60 can be used to purify the secondary steam separated by the separator 12, and the purified secondary steam can be sent to a steam compressor 20.

[0087] Specifically, the secondary steam generated from the evaporation of radioactive waste liquid rises in the separation device 12 and first passes through the first demister 121 for demisting, then passes through the purification device 60, and is further purified by passing through the packing layer 63, the second demister 61, and the spray. The secondary steam exiting the purification device 60 directly enters the steam compression device 20 for compression.

[0088] In addition, the condensate pump 83 can send a portion of the condensate at approximately 112°C from the steam generator 30 to the outlet pipe 104 of the steam compressor 20 to eliminate the superheat of the pressurized and heated secondary steam. This portion of condensate is vaporized at the outlet of the steam compressor 20, reducing the temperature of the secondary steam and turning it into saturated steam that enters the heating device 11 to heat the radioactive waste liquid. A small amount of condensate is also sent to the purification device 60 as a spray liquid. During operation, the secondary steam is circulated and sprayed within the purification device 60 by the spray liquid pump 84 to ensure the purification effect.

[0089] In some embodiments, the condensate from the first preheating device 51 after exchanging heat with the radioactive waste liquid can be collected using the condensate storage container 43. The purification coefficient of the treatment system can be verified by detecting the concentration of the collected condensate.

[0090] Furthermore, a cooling device is provided between the condensate storage container 43 and the first preheating device 51. The cooling device cools the condensate flowing out of the first preheating device 51 and then collects it into the condensate storage container 43.

[0091] In addition, a large amount of non-condensable gas exists in the equipment before the system is put into operation, and a small amount of non-condensable gas will be generated when the radioactive waste liquid is heated during the system operation. There is at least one exhaust port at the top and bottom of the heating device 11 and the second preheating device 52. Each exhaust port is connected to an exhaust valve. During the system operation, the exhaust valve is opened at regular intervals to remove the non-condensable gas in the system and improve the heat exchange efficiency of the equipment.

[0092] In some embodiments, the operating current of the steam compressor 20 can also be monitored to prevent abnormalities in the steam compressor 20. Specifically, when the operating current of the steam compressor 20 decreases, it indicates that the steam compressor 20 is experiencing surge. At this time, the regulating valve of the outlet pipe 104 of the steam generator 30 can be controlled to replenish air to the inlet of the steam compressor 20 to prevent surge.

[0093] Regarding the embodiments of the present invention, it should also be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0094] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for treating radioactive liquid waste, characterized by, The method comprises the following steps: continuously feeding radioactive waste liquid into an evaporator, the evaporator comprising a heating device and a separation device, the radioactive waste liquid circulating between the heating device and the separation device; wherein the heating device heats the radioactive waste liquid to make it boil, and the boiled radioactive waste liquid is subjected to vapor-liquid separation in the separation device to produce secondary steam, so as to concentrate the radioactive waste liquid; the secondary steam produced by evaporating the radioactive waste liquid is introduced into a steam compression device, the secondary steam is compressed and heated by the steam compression device, and then is delivered to the heating device as a first heat source of the heating device to exchange heat with the radioactive waste liquid; continuously discharging the concentrated radioactive waste liquid in the evaporator, and controlling the discharge flow rate of the concentrated radioactive waste liquid to ensure that the radioactive waste liquid is concentrated to a predetermined multiple; a purification device is arranged between the separation device and the steam compression device; the method further comprises the following steps: purifying the secondary steam separated by the separation device by using the purification device; delivering the secondary steam purified by the purification device to the steam compression device; a spraying member is arranged at the top of the purification device, and sprays in the purification device to clean the secondary steam entering the purification device; a second demister is arranged in the purification device to perform demisting treatment on the secondary steam entering the purification device; and the spraying member is arranged above the second demister.

2. The method of claim 1, wherein, the radioactive waste liquid naturally circulates between the heating device and the separation device due to the density difference caused by temperature change; or a circulating pump is arranged on a circulating pipeline between the heating device and the separation device, and the circulating pump drives the radioactive waste liquid to circulate between the heating device and the separation device.

3. The method of claim 1, wherein, The method further comprises the following steps: continuously feeding the radioactive waste liquid in a feeding device into the evaporator; wherein a feeding pipeline is arranged in communication between the feeding device and the evaporator, a backflow pipeline is connected to the feeding device and arranged on the feeding pipeline, and the backflow pipeline is used to make at least part of the radioactive waste liquid in the feeding pipeline backflow into the feeding device; adjusting the flow rate of the radioactive waste liquid in the backflow pipeline to control the feeding flow rate of the radioactive waste liquid fed into the heating device.

4. The method of claim 1, wherein, The method further comprises the following steps: steam generated by a steam generation device is used as a second heat source of the heating device to compensate for the steam required by the heating device, and to provide a heat source for the heating device when the radioactive waste liquid treatment system is started.

5. The method of claim 4, wherein, The step of continuously feeding the radioactive waste liquid into the evaporator comprises the following steps: continuously delivering the radioactive waste liquid in the feeding device to a first preheating device; delivering condensed liquid in the steam generation device to the first preheating device to preheat the radioactive waste liquid; feeding the preheated radioactive waste liquid into the evaporator.

6. The method of claim 5, wherein, The step of continuously feeding the radioactive waste liquid into the evaporator further comprises the following steps: delivering the preheated radioactive waste liquid in the first preheating device to a second preheating device; The heating steam generated by the vapor compression device is delivered to the heating device and then to the second preheating device as a heat source of the second preheating device to preheat the radioactive waste liquid twice; The radioactive waste liquid preheated twice is fed to the evaporator.

7. The method of claim 6, wherein, Further comprising: The condensate in the heating device and the second preheating device flows to the vapor generation device by gravity to supplement the condensate for the vapor generation device, which is condensed from the vapor in the heating device and the second preheating device after heat exchange with the radioactive waste liquid.

8. The method of claim 7, wherein, A trap is arranged between the heating device and the vapor generation device, and / or a trap is arranged between the second preheating device and the vapor generation device; the method further comprises: The trap is used to separate the condensate flowing out of the heating device and / or the second preheating device into gas and liquid to block the gas mixed in the condensate from entering the vapor generation device.

9. The method of claim 1, wherein, The separation device is provided with a first demister, and the method further comprises: The first demister is used to remove foam from the steam in the separation device before the steam leaves the separation device.

10. The method of claim 6, wherein, Further comprising: A condensate storage container is used to collect the condensate flowing out of the first preheating device after heat exchange with the radioactive waste liquid.

11. The method of claim 10, wherein, A cooling device is further arranged between the condensate storage container and the first preheating device, and the method further comprises: the cooling device is used to cool the condensate flowing out of the first preheating device and then collect the condensate into the condensate storage container.

12. A radioactive liquid waste treatment system, comprising: For implementing the radioactive waste liquid treatment method according to any one of claims 1-11, comprising: An evaporator is used to evaporate and concentrate the radioactive waste liquid; the evaporator comprises: A heating device, which forms a heating cavity to provide a flow channel for heating steam, and is provided with a liquid flow channel for the flow of the radioactive waste liquid, and the heating steam can exchange heat with the radioactive waste liquid to heat treat the radioactive waste liquid; A separation device, which is connected with the liquid flow channel of the heating device to separate the boiling radioactive waste liquid after the heating treatment into gas and liquid to concentrate the radioactive waste liquid; A circulating pipeline, which is connected with the separation device and the heating device respectively to provide a channel for the circulation of the radioactive waste liquid between the heating device and the separation device; A vapor compression device, which is arranged between the separation device and the inlet of the heating cavity, and is used to compress and heat the secondary steam to serve as a first heat source of the heating device; A residual liquid storage container, which is connected with the heating device to receive and store the residual liquid concentrated by evaporation of the radioactive waste liquid; The residual liquid storage container and the heating device are provided with a liquid discharge valve to control the discharge flow of the residual liquid; A purification device is arranged between the separation device and the vapor compression device to purify the secondary steam; The top of the purification device is provided with a spraying member which sprays in the purification device to clean the secondary steam entering the purification device. A second demister is arranged in the purification device to demist the secondary steam entering the purification device; and the spraying member is arranged above the second demister.

13. The system of claim 12, wherein, Further comprising: A circulating pump is arranged on the circulating pipeline to drive the radioactive waste liquid to circulate between the separation device and the heating device.

14. The system of claim 12, wherein, Further comprising: A feeding device is connected with the evaporator to store the radioactive waste liquid to be treated; A feeding pipeline is connected between the feeding device and the circulating pipeline; A reflux pipeline is connected at one end with the feeding device and at the other end with the feeding pipeline, and is used to provide a passage for refluxing at least part of the radioactive waste liquid in the feeding pipeline to the feeding device; wherein a reflux valve is arranged on the reflux pipeline to control the flow of the radioactive waste liquid in the reflux pipeline.

15. The system of claim 14, wherein, Further comprising: A steam generating device is arranged to heat the water to generate steam, and is connected with the heating device to provide a second heat source for the heating device.

16. The system of claim 15, wherein, Further comprising: A first preheating device is arranged between the feeding device and the evaporator, and is connected with the steam generating device to provide the first preheating device with condensed liquid to preheat the radioactive waste liquid; A second preheating device is arranged between the first preheating device and the evaporator, and is connected in communication with the heating cavity of the heating device to provide the second preheating device with heated steam to secondarily preheat the radioactive waste liquid.

17. The system of claim 16, wherein, A trap is arranged between the heating device and the steam generating device to block the gas mixed in the condensed liquid formed after the heated steam in the heating device exchanges heat from entering the steam generating device; and / or A trap is arranged between the second preheating device and the steam generating device to block the gas mixed in the condensed liquid formed after the heated steam in the second preheating device exchanges heat from entering the steam generating device.

18. The system of claim 16, wherein, Further comprising: A condensed liquid storage container is connected with the first preheating device to receive and store the condensed liquid after the radioactive waste liquid exchanges heat in the first preheating device; A cooling device is arranged between the condensed liquid storage container and the first preheating device to cool the condensed liquid.

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