Inland nuclear facility low-level radioactive liquid effluent atomized airborne discharge system

Abstract

The application discloses a kind of inland nuclear facilities low radioactive liquid effluent atomization airborne discharge systems, including being arranged in the bottom of nuclear island chimney atomization discharge device, with waste liquid treatment system connection waste liquid discharge buffer tank and with external exhaust system connection gas chamber;Waste liquid discharge buffer tank is connected with atomization discharge device, and gas chamber is arranged below atomization discharge device;Atomization discharge device includes atomization air power source, at least two layers annular pipeline and several atomization nozzles, and atomization air power source is connected annular pipeline;Atomization nozzle is evenly arranged on annular pipeline, and the direction of nozzle jetting is obliquely upward to the center of annular pipeline.Utilize the atomization discharge device arranged in the bottom of nuclear island chimney to convert waste liquid with low radioactive liquid effluent to be discharged into fine and dense water mist, and then discharge together with the exhaust in nuclear island chimney, and the discharge mode is efficient and not affected by weather.And process flow is simple, without building large-scale facilities, applicable to inland nuclear facilities.

Description

Technical Field

[0001] This invention relates to the field of low-radioactive liquid effluent discharge technology for inland nuclear facilities, and particularly to a low-radioactive liquid effluent atomization gaseous discharge system for inland nuclear facilities. Background Technology

[0002] The receiving water bodies for radioactive liquid effluents from inland nuclear facilities are mostly rivers, lakes, and reservoirs, many of which serve as sources of drinking water for residents and irrigation water for farmland. To better protect the public and the water environment, the Ministry of Environmental Protection, in GB 6249-2011 "Regulations for Environmental Radiation Protection of Nuclear Power Plants," stipulated that for inland sites, the concentration of radioactive nuclides other than tritium and 14C in the effluents should not exceed 100 Bq / L, aiming to achieve near-zero emissions of radioactive liquid effluents from inland nuclear power plants.

[0003] For inland nuclear facilities without suitable receiving water bodies, in order to meet the strict requirements of GB 6249-2011 on the radioactive release of inland sites, it is necessary to convert the treated low-level radioactive waste liquid that meets the emission limits into gaseous effluent through appropriate emission processes for discharge, so as to realize the liquid-to-gas emission of radioactive liquid effluent, which is referred to as gaseous emission.

[0004] Currently, inland nuclear facilities primarily utilize natural evaporation pond technology, a method that uses solar energy to evaporate and remove excess water from radioactive waste. This method has simple operational requirements, requires minimal daily maintenance, and features a high purification coefficient for low-level waste, large processing capacity, and energy efficiency. However, natural evaporation ponds require a large operating area and long hours of sunshine; their usability depends on specific site conditions, limiting its application and resulting in relatively low efficiency. Furthermore, it cannot address the risk of radioactive nuclides being introduced into the biosphere through biological invasion, and the sludge generated after evaporation treatment may pose potential radioactive contamination to the surrounding soil and environment. The decommissioning process also involves substantial site cleanup and environmental remediation work.

[0005] Furthermore, Chinese patent application "An Atomization Evaporation System for Discharging Nuclear Power Plant Wastewater Using an Air-Cooled Tower" (application number 201620070507.9, publication date August 24, 2016) discloses a scheme for atomizing nuclear power plant wastewater and then discharging it through an air-cooled tower. It reveals that the wastewater can be atomized using either high-pressure atomization or air atomization, and utilizes the high wind speed, relatively high temperature, and large gas-liquid contact area within the air-cooled tower to achieve elevated discharge of the atomized wastewater. However, due to the large footprint and high construction cost of air-cooled towers, they are generally only built in nuclear power plants and are not essential for inland nuclear facilities, especially small inland nuclear facilities not used for power generation. Therefore, the applicability of this scheme is limited and cannot be directly applied to inland nuclear facilities. Moreover, this scheme relies primarily on the evaporation of the atomized wastewater within the air-cooled tower for discharge. For sites with frequent rainy weather and high humidity, where environmental conditions are unfavorable for evaporation, the discharge efficiency of this scheme is limited.

[0006] Therefore, for inland nuclear facilities that do not have receiving water bodies and are not equipped with air-cooled towers, there is a need for more suitable waste liquid discharge methods. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address at least one defect of the related technologies mentioned in the background: the operation facilities of natural evaporation ponds occupy a large area, require a long period of sunshine, and are inefficient. The present invention provides a low-radioactivity liquid effluent atomization gaseous emission system for inland nuclear facilities.

[0008] The technical solution adopted by the present invention to solve its technical problem is: to construct a low-radioactivity liquid effluent atomization gaseous emission system for inland nuclear facilities, including an atomization emission device located at the bottom of the nuclear island chimney, a waste liquid emission buffer tank connected to a waste liquid treatment system, and a gas collection chamber connected to an external exhaust system; the waste liquid emission buffer tank is connected to the atomization emission device, and the gas collection chamber is located below the atomization emission device;

[0009] The atomizing emission device includes an atomizing air power source, at least two layers of annular pipelines, and a number of atomizing nozzles. The atomizing air power source is connected to the annular pipelines. The atomizing nozzles are evenly distributed on the annular pipelines, and the nozzles spray obliquely upward toward the central axis of the nuclear island chimney.

[0010] Preferably, in the inland nuclear facility low-radioactive liquid effluent atomization airborne emission system of the present invention, the waste liquid emission buffer tank is provided with an inlet, an outlet, an exhaust outlet, an overflow outlet, and a liquid level measuring port. The outlet is located at the bottom of the waste liquid emission buffer tank, the inlet, the exhaust outlet, and the liquid level measuring port are respectively located at different positions on the top of the waste liquid emission buffer tank, and the overflow outlet is located on the side wall of the waste liquid emission buffer tank and below the inlet.

[0011] Preferably, the inland nuclear facility low-radioactive liquid effluent atomization airborne emission system of the present invention further includes a waste liquid transfer pump, one end of which is connected to the waste liquid emission buffer tank and the other end is connected to the atomization emission device.

[0012] Preferably, in the inland nuclear facility low-radioactivity liquid effluent atomization gaseous emission system of the present invention, the pressure of the waste liquid transfer pump is 0.5MPa-2MPa.

[0013] Preferably, in the inland nuclear facility low-radioactivity liquid effluent atomization airborne emission system of the present invention, the waste liquid transfer pump is connected to the waste liquid emission buffer tank and the atomization emission device through pipelines, and the pipelines are equipped with a number of valves.

[0014] Preferably, the inland nuclear facility low-radioactive liquid effluent atomization gaseous emission system of the present invention further includes a retention area for collecting all waste liquid in the waste liquid discharge buffer tank when the waste liquid discharge buffer tank is damaged, and the waste liquid discharge buffer tank is placed in the retention area.

[0015] Preferably, the inland nuclear facility low-radioactive liquid effluent atomization gaseous emission system of the present invention further includes a collection pit for collecting falling atomized droplets and connecting to the waste liquid treatment system, the collection pit being located below the gas collection chamber; the inner layer of the collection pit is provided with a steel cladding and equipped with a sampling and analysis device.

[0016] Preferably, in the inland nuclear facility low-radioactivity liquid effluent atomization gaseous emission system of the present invention, the atomizing nozzle is arranged obliquely upward at an angle of 60 degrees to the horizontal line of the annular pipeline.

[0017] Preferably, in the inland nuclear facility low-radioactivity liquid effluent atomization airborne emission system of the present invention, the average particle size of the atomized droplets ejected from the atomizing nozzle is less than 20 μm.

[0018] Preferably, in the inland nuclear facility low-radioactive liquid effluent atomization airborne emission system of the present invention, the atomizing nozzle is an external mixing air atomizing nozzle.

[0019] By implementing this invention, the following beneficial effects are achieved:

[0020] The low-level radioactive liquid effluent atomization airborne emission system for inland nuclear facilities of this invention discharges the low-level radioactive liquid effluent to be discharged through the nuclear facility's chimney. Atomizing nozzles arranged at the bottom of the chimney convert the waste liquid containing the low-level radioactive liquid effluent into a fine water mist, meeting the requirements of GB6249-2011. This mist is then discharged along with the exhaust gas from the chimney. The exhaust air within the chimney provides the power for the atomized low-level radioactive liquid effluent emission, making it more efficient and unaffected by weather compared to emission methods that rely solely on evaporation. Furthermore, an external exhaust system enhances the airflow, further improving emission efficiency.

[0021] Compared to methods that utilize large air-cooled towers to discharge atomized waste liquid, the low-radioactive liquid effluent atomization airborne emission system for inland nuclear facilities of this invention is suitable for inland nuclear facilities. Leveraging the small size, simple structure, convenient construction, and flexible configuration of the nuclear island chimney, it can ideally solve the problem of low-radioactive liquid effluent discharge for inland nuclear facilities without receiving water bodies, especially for small nuclear facilities not used for power generation. This solution features a simple process, convenient operation and maintenance, no need for constructing new large-scale facilities, good economic efficiency, and a short construction period. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of the overall structure of an inland nuclear facility low-radioactive liquid effluent atomization gaseous emission system in one embodiment of the present invention;

[0024] Figure 2 This is the present invention. Figure 1 A schematic diagram of the waste liquid discharge buffer tank in the middle;

[0025] Figure 3 This is the present invention. Figure 1 A partial structural diagram of the atomizing emission device. Detailed Implementation

[0026] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0028] In the description of the invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a chemical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] Furthermore, the term "nuclear facility" as used in this invention refers to a collective term for nuclear fuel manufacturing plants, nuclear reactors, research reactors, radioactive waste treatment and disposal facilities, and other facilities containing radioactive materials that require strict supervision and management. Liquid effluents refer to the flow of radioactive materials released into the environment via liquid pathways. The nuclear island refers to the nuclear reactor and all related systems within the containment vessel of a nuclear power plant.

[0031] See Figures 1 to 3 An embodiment of the present invention discloses a low-radioactivity liquid effluent atomization airborne emission system for inland nuclear facilities, including an atomization emission device 1 located at the bottom of the nuclear island chimney 3, a waste liquid emission buffer tank 21 connected to a waste liquid treatment system 4, and a gas collection chamber 23 connected to an external exhaust system 5; the waste liquid emission buffer tank 21 is connected to the atomization emission device 1, and the gas collection chamber 23 is located below the atomization emission device 1.

[0032] The atomizing emission device 1 includes an atomizing air power source 11, at least two layers of annular pipelines 12, and several atomizing nozzles 13. The atomizing air power source 11 is connected to the annular pipelines 12. The atomizing nozzles 13 are evenly arranged on the annular pipelines 12, and the nozzle spray direction is obliquely upward toward the central axis of the nuclear island chimney 3.

[0033] Specifically:

[0034] Considering the potential adverse effects of the small size of the nuclear island chimney 3 on waste liquid atomization, a double-layer atomizing nozzle 13 is adopted. Two layers of annular pipelines 12 are located at the bottom of the nuclear island chimney 3. The double-layer arrangement increases the number of atomizing nozzles 13, making the atomized droplet distribution more uniform. The atomizing nozzles 13 are evenly distributed on the annular pipelines 12, with the nozzles 13 and the horizontal line of the annular pipelines 12 arranged obliquely upward at a 60-degree angle, so that the spray direction is in the same direction as the exhaust direction of the nuclear island chimney 3, enhancing the flowability of the atomized droplets and facilitating their discharge with the exhaust air. In some other embodiments, the annular pipelines 12 can be configured with more layers according to actual needs and the load-bearing capacity of the nuclear island chimney 3; the number of layers of the annular pipelines 12 is not limited here.

[0035] To enhance the atomization effect of the waste liquid, the atomizing nozzle 13 adopts an external mixing air atomizing nozzle 13. Preferably, a 304 stainless steel external mixing air atomizing nozzle 13 is used, where the high-speed airflow and liquid jet mix outside the nozzle, enhancing the atomization effect of the waste liquid without requiring high pressure and reducing the likelihood of clogging the atomizing nozzle 13. The atomizing air power source 11 for auxiliary atomization uses an air compressor to enhance power and facilitates air pressure adjustment, ensuring the atomization effect. Through the air jet provided by the air compressor and the appropriate orifice diameter of the atomizing nozzle 13, the average particle size of the atomized droplets ejected by the atomizing nozzle 13 is below 20μm.

[0036] like Figure 1 As shown, the inland nuclear facility low-radioactive liquid effluent atomization airborne emission system of the present invention includes emission auxiliary facilities 2 that provide necessary auxiliary functions for the atomization emission device 1. In addition to the waste liquid emission buffer tank 21 and gas collection chamber 23 mentioned above, emission auxiliary facilities 2 also include a retention pool 24, a waste liquid transfer pump 22, a collection pit, and supporting valves and pipelines.

[0037] To temporarily store waste liquid, a waste liquid discharge buffer tank 21 is connected to the waste liquid treatment system 4. The waste liquid discharge buffer tank 21 is equipped with an inlet 211, a discharge outlet 212, an exhaust outlet 213, an overflow outlet 214, and a liquid level measuring port 215. The discharge outlet 212 is located at the bottom of the waste liquid discharge buffer tank 21. The inlet 211, exhaust outlet 213, and liquid level measuring port 215 are located at different positions on the top of the waste liquid discharge buffer tank 21. The overflow outlet 214 is located on the side wall of the waste liquid discharge buffer tank 21 and below the inlet 211. Preferably, the waste liquid discharge buffer tank 21 is a cylindrical vertical stainless steel storage tank with an effective volume of 8 cubic meters, used for storing waste liquid to be discharged. The exhaust outlet 213 prevents overpressure or vacuum formation in the waste liquid discharge buffer tank 21; the overflow outlet 214, connected to a pipe, can discharge the overflowing liquid to the corresponding collection point of the radioactive hydrophobic collection system. The waste liquid discharge buffer tank 21 is designed to prevent gaps and depressions, and is equipped with cleaning and decontamination interfaces, allowing for complete emptying. The waste liquid discharge buffer tank 21 can be secured to the floor with anchor bolts. In some other embodiments, the waste liquid discharge buffer tank 21 also includes a manhole 216 for access, facilitating maintenance and cleaning.

[0038] To prevent the leakage of radioactive liquid into the environment, a retention tank 24 is provided to collect all waste liquid in the waste liquid discharge buffer tank 21 in the event of a breakage. The waste liquid discharge buffer tank 21 is placed in a retention area to collect all waste liquid in the tank when the waste liquid discharge buffer tank 21 is broken.

[0039] To ensure the proper transport of the waste liquid to be discharged, a waste liquid transfer pump 22 is provided. One end of the waste liquid transfer pump 22 is connected to the waste liquid discharge buffer tank 21, and the other end is connected to the atomizing discharge device 1. Preferably, one end of the waste liquid transfer pump 22 is connected to the discharge port 212 of the waste liquid discharge buffer tank 21, and the other end is connected to the double-layer annular pipeline 12 of the atomizing discharge device 1. The waste liquid transfer pump 22 is a horizontal centrifugal pump, and the pressure-bearing components of the horizontal centrifugal pump are made of stainless steel, providing reliable mechanical sealing performance. The recommended pressure for the waste liquid transfer pump 22 is 0.5MPa to 2MPa.

[0040] Furthermore, the waste liquid transfer pump 22 is connected to the waste liquid discharge buffer tank 21 and the atomizing discharge device 1 via pipelines, and several valves are installed on the pipelines. Preferably, the connection between the waste liquid transfer pump 22 and the relevant pipelines is equipped with measures to collect and seal leaked water. A drain pipe is provided at the base of the waste liquid transfer pump 22. The valves on the pipelines are straight-through valves to reduce pipeline resistance and the possibility of blockage. The valve sealing material has sufficient radiation resistance to ensure the expected service life. All remotely controlled valves can provide valve position indication; frequently operated valves are electric valves that can be operated remotely from the control panel, and infrequently operated valves are manual valves.

[0041] To reduce waste liquid leakage into the environment, a collection pit is provided to collect falling atomized droplets and connect them to the waste liquid treatment system 4. The collection pit is located below the gas collection chamber 23. The inner layer of the collection pit is lined with steel and equipped with a sampling and analysis device. Preferably, the collection pit is located at the bottom of the gas collection chamber 23 to collect falling atomized droplets. The sampling and analysis device in the pit allows for sampling and analysis of the returned droplets. After analysis, the returned droplets can be sent to the waste liquid discharge buffer tank 21 for continued atomization and discharge or sent back to the waste liquid treatment system 4 for further treatment, thus solving the problem of droplet settling and falling back during the atomization and discharge process and reducing waste liquid leakage into the environment.

[0042] By implementing this invention, the following beneficial effects are achieved:

[0043] The low-radioactive liquid effluent atomization airborne emission system for inland nuclear facilities of the present invention discharges the low-radioactive liquid effluent to be discharged through the chimney of the nuclear facility. Atomizing nozzles 13 arranged at the bottom of the nuclear island chimney 3 convert the waste liquid containing the low-radioactive liquid effluent to be discharged into a fine water mist, meeting the requirements of GB 6249-2011. This mist is then discharged along with the exhaust gas inside the nuclear island chimney 3. The exhaust air inside the chimney provides the power for the atomized low-radioactive liquid effluent emission, which is more efficient and unaffected by weather compared to emission methods that rely solely on evaporation. Furthermore, an external exhaust system 5 enhances the airflow, further improving emission efficiency.

[0044] Compared to methods that utilize large air-cooled towers to discharge atomized waste liquid, the low-radioactive liquid effluent atomization airborne emission system for inland nuclear facilities of this invention is suitable for inland nuclear facilities. Leveraging the small size, simple structure, convenient construction, and flexible configuration of the nuclear island chimney 3, it can ideally solve the problem of low-radioactive liquid effluent discharge for inland nuclear facilities without receiving water bodies, especially for small nuclear facilities not used for power generation. This solution features a simple process, convenient operation and maintenance, no need for constructing new large-scale facilities, good economic efficiency, and a short construction period.

[0045] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those skilled in the art, the above embodiments or technical features can be freely combined, and several modifications and improvements can be made without departing from the concept of the present invention. These all fall within the protection scope of the present invention. That is, the embodiments described "in some embodiments" can be freely combined with any of the embodiments above and below. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A gas-carrier atomization emission system for low-radioactive liquid effluents from inland nuclear facilities, used in the chimneys of nuclear facilities to discharge low-radioactive liquid effluents to be emitted, characterized in that, It includes an atomizing emission device (1) located at the bottom of the nuclear island chimney (3), a waste liquid discharge buffer tank (21) connected to the waste liquid treatment system (4), and a gas collection chamber (23) connected to the external exhaust system (5); the waste liquid discharge buffer tank (21) is connected to the atomizing emission device (1), and the gas collection chamber (23) is located below the atomizing emission device (1); The atomizing emission device (1) includes an atomizing air power source (11), at least two layers of annular pipelines (12) located at the bottom of the nuclear island chimney (3), and a plurality of atomizing nozzles (13). The atomizing air power source (11) is connected to the annular pipelines (12). The atomizing nozzles (13) are evenly arranged on the annular pipelines (12), and the nozzles spray obliquely upward toward the central axis of the nuclear island chimney (3) so that the spray direction is in a co-current relationship with the exhaust direction. The atomizing nozzles (13) are external mixing air atomizing nozzles (13). The waste liquid discharge buffer tank (21) is provided with an inlet (211), a discharge port (212), an exhaust port (213), an overflow port (214), and a liquid level measuring port (215). The discharge port (212) is located at the bottom of the waste liquid discharge buffer tank (21). The inlet (211), the exhaust port (213), and the liquid level measuring port (215) are respectively located at different positions on the top of the waste liquid discharge buffer tank (21). The overflow port (214) is located on the side wall of the waste liquid discharge buffer tank (21) and below the inlet (211).

2. The atomized gaseous emission system for low-radioactivity liquid effluents from inland nuclear facilities according to claim 1, characterized in that, It also includes a waste liquid transfer pump (22), one end of which is connected to the waste liquid discharge buffer tank (21), and the other end is connected to the atomizing discharge device (1).

3. The atomized gaseous emission system for low-radioactivity liquid effluents from inland nuclear facilities according to claim 2, characterized in that, The pressure of the waste liquid transfer pump (22) is 0.5MPa - 2MPa.

4. The atomized gaseous emission system for low-radioactivity liquid effluents from inland nuclear facilities according to claim 2, characterized in that, The waste liquid transfer pump (22) is connected to the waste liquid discharge buffer tank (21) and the atomizing discharge device (1) through pipelines, and the pipelines are equipped with several valves.

5. The atomized gaseous emission system for low-radioactivity liquid effluents from inland nuclear facilities according to claim 1, characterized in that, It also includes a retention area for collecting all waste liquid in the waste liquid discharge buffer tank (21) in the event of damage to the waste liquid discharge buffer tank (21), wherein the waste liquid discharge buffer tank (21) is placed in the retention area.

6. The atomized gaseous emission system for low-radioactivity liquid effluents from inland nuclear facilities according to claim 1, characterized in that, It also includes a collection pit for collecting falling atomized droplets and connecting to the waste liquid treatment system (4), the collection pit being located below the gas collection chamber (23); the inner layer of the collection pit is covered with steel and equipped with a sampling and analysis device.

7. The atomized gaseous emission system for low-radioactivity liquid effluents from inland nuclear facilities according to claim 1, characterized in that, The atomizing nozzle (13) is arranged at a 60-degree angle to the horizontal line of the annular pipeline (12).

8. The atomized gaseous emission system for low-radioactivity liquid effluents from inland nuclear facilities according to claim 1, characterized in that, The atomized droplets ejected from the atomizing nozzle (13) have an average particle size of less than 20 μm.

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