Methods to reduce effluent emissions from the conventional island of nuclear power plants

Abstract

This invention discloses a method for reducing effluent emissions from the conventional island of a nuclear power plant. The conventional island of a nuclear power plant is equipped with a feedwater chemical sampling system, a steam conversion system, and a condenser circulation system. This method reduces the overall effluent emissions from the conventional island of the nuclear power plant by shutting down some pipelines of the feedwater chemical sampling system, reducing the effluent emissions from the steam conversion system, and reducing the backwashing frequency of the condenser circulation system. This reduces ammonia nitrogen emissions, alleviates environmental monitoring pressure, and improves environmental friendliness. At the same time, the downstream wastewater discharge is reduced, and the upstream water production can be further reduced, thus reducing water production costs and workload and improving economic efficiency.

Description

Technical Field

[0001] This invention relates to the field of effluent control in conventional islands of nuclear power plants, and more particularly to a method for reducing effluent emissions from conventional islands of nuclear power plants. Background Technology

[0002] Analysis suggests that there is potential for optimization in the wastewater discharge from the existing SEL (Conventional Island Wastewater Storage and Discharge System) of the power plant. According to the system design, SEL wastewater primarily originates from the following sources: approximately 16% from continuous drainage monitoring of the SIT (Feedwater Chemical Sampling System), approximately 9% from continuous wastewater discharge from the STR (Steam Converter System), 9% from backwashing drainage of the CEX001FI (Condenser Circulating Pump Outlet Filter), approximately 16% from continuous drainage of the ASG003BA (Steam-Driven Feedwater Pump Drain Tank), and other discontinuous drainage, of which approximately 50% cannot be quantified.

[0003] The feedwater chemical sampling system, steam conversion system, and condenser circulation system have potential for optimization. The effluent from the conventional island generated by these three systems will be collected in the SEL system and discharged after passing chemical monitoring. The monthly discharge volume is substantial, increasing environmental monitoring pressure. Furthermore, the SEL system requires sampling and monitoring before discharge, resulting in a large discharge volume and increasing the sampling and analysis workload. Moreover, the large downstream discharge volume necessitates upstream replenishment of water to each system at the same influent rate to maintain system water balance and ensure the normal operation of the conventional island. Therefore, the large upstream water production volume increases water production costs and workload. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for reducing the amount of effluent from the conventional island of a nuclear power plant.

[0005] The technical solution adopted by this invention to solve its technical problem is: to construct a method for reducing the effluent emissions from the conventional island of a nuclear power plant, wherein the conventional island of the nuclear power plant is equipped with a feedwater chemical sampling system, a steam conversion system, and a condenser circulation system, comprising the following steps:

[0006] S1: Determine whether the pipeline of the water supply chemical sampling system is put into operation based on whether the pipeline is equipped with online monitoring instruments and whether the pipeline of the water supply chemical sampling system is a necessary operating line;

[0007] S2: Detect the sodium content in the emissions from the steam conversion system at different time points, form a relationship between sodium content and time, obtain a sodium content change curve based on the relationship between sodium content and time, and determine whether the steam conversion system should discharge pollutants based on the sodium content and the sodium content change curve;

[0008] S3: Set the backwashing frequency of the condenser circulation system to a preset frequency, obtain the real-time differential pressure value of the condenser circulation system, and adjust the backwashing frequency of the condenser circulation system according to the real-time differential pressure value.

[0009] In some embodiments, in step S1, if the pipeline of the water supply chemical sampling system is not equipped with an online monitoring instrument, the pipeline of the corresponding water supply chemical sampling system will be shut down.

[0010] If the pipeline of the water supply chemical sampling system is equipped with online monitoring instruments, and these instruments are required to be in operation, then the pipeline of the corresponding water supply chemical sampling system shall remain in operation.

[0011] In some embodiments, in step S1, if there are two lines of operating pipelines with the same function in the water supply chemical sampling system, and both lines of operating pipelines are equipped with online monitoring instruments and are not required to operate, then the two lines of operating pipelines are switched to operation.

[0012] In some embodiments, the steam conversion system includes a steam converter, a drain tank, a water pipeline, a detection pipeline, and a drain pipeline;

[0013] The steam converter is connected to the inlet of the sewage tank via the water pipeline. The water pipeline is equipped with an electric valve and a manual valve. The detection pipeline is connected to the water pipeline, and the sewage pipeline is connected to the outlet of the sewage tank. The detection pipeline is equipped with a water quality detector.

[0014] In some embodiments, in step S2, if the sodium content is less than a preset threshold and the sodium content change curve fluctuates within a preset range, the manual valve is closed to stop the discharge.

[0015] If the sodium content is less than a preset threshold and the sodium content change curve is on an upward trend, or if the sodium content is greater than or equal to the preset threshold, then the manual valve is opened to discharge sewage.

[0016] In some embodiments, in step S2, if the sodium content is less than a preset threshold and the sodium content change curve is on an upward trend after the manual valve is closed, or if the sodium content is greater than or equal to the preset threshold, then the manual valve is opened to discharge sewage.

[0017] If the sodium content is less than a preset threshold after the manual valve is opened and the sodium content change curve fluctuates within a preset range, then the manual valve is closed to stop the discharge.

[0018] In some embodiments, the preset threshold is 3000 μg / kg.

[0019] In some embodiments, the preset frequency is once every 16 hours.

[0020] In some embodiments, in step S3, if the real-time differential pressure value is less than the preset differential pressure value, the automatic backwashing frequency of the condenser circulation system is reduced.

[0021] If the real-time differential pressure value is greater than or equal to the preset differential pressure value, the backwashing frequency of the condenser circulation system is increased and the backwashing process is started until the real-time differential pressure value is less than the preset differential pressure value, and then the automatic backwashing frequency is reduced.

[0022] In some embodiments, the preset differential pressure value is 0.04 MPa.

[0023] Implementing this invention has the following beneficial effects: This method for reducing effluent emissions from the conventional island of a nuclear power plant reduces the overall effluent emissions from the conventional island by shutting down some feedwater chemical sampling system pipelines, reducing effluent emissions from the steam conversion system, and reducing the backwashing frequency of the condenser circulation system. This reduces ammonia nitrogen emissions, lowers environmental monitoring pressure, and improves environmental friendliness. At the same time, the reduction in downstream wastewater discharge allows for a further reduction in upstream water production, lowering water production costs and workload, and improving economic efficiency. Attached Figure Description

[0024] To more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort. In the drawings:

[0025] Figure 1 These are schematic diagrams illustrating the operation of the water chemical sampling system in some embodiments of the present invention;

[0026] Figure 2 These are schematic diagrams of specific embodiments of the water chemical sampling system in some embodiments of the present invention;

[0027] Figure 3 These are schematic diagrams of the steam conversion system in some embodiments of the present invention;

[0028] Figure 4 These are schematic diagrams illustrating the operation of the steam conversion system in some embodiments of the present invention;

[0029] Figure 5 This is a schematic diagram of the operation of the condenser circulation system in some embodiments of the present invention. Detailed Implementation

[0030] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientations or positional relationships indicated by terms such as "front," "rear," "upper," "lower," "left," "right," "longitudinal," "horizontal," "vertical," "horizontal," "top," "bottom," "inner," "outer," "head," and "tail" are based on the orientations or positional relationships shown in the accompanying drawings, and are constructed and operated in a specific orientation. They are only for the convenience of describing this technical solution and do not indicate that the device or element referred to must have a specific orientation; therefore, they should not be construed as limitations on this invention.

[0031] It should also be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. When an component is referred to as being "on" or "below" another component, the component can be located "directly" or "indirectly" on the other component, or there may be one or more intermediary components. The terms "first," "second," "third," etc., are only for the convenience of describing this technical solution and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0032] Please see Figures 1 to 5 This is a method for reducing effluent emissions from the conventional island of a nuclear power plant, as described in some embodiments of the present invention. The conventional island of the nuclear power plant is equipped with a feedwater chemical sampling system, a steam conversion system 2, and a condenser circulation system. The method includes the following steps:

[0033] S1: Determine whether the water supply chemical sampling system pipeline should be put into operation based on whether it is equipped with online monitoring instruments and whether it is a necessary operating line.

[0034] S2: Detect the sodium content in the emissions of steam conversion system 2 at different time points, form the relationship between sodium content and time, obtain the sodium content change curve based on the relationship between sodium content and time, and determine whether steam conversion system 2 should discharge pollutants based on the sodium content and the sodium content change curve.

[0035] S3: Set the backflushing frequency of the condenser circulation system to the preset frequency, obtain the real-time differential pressure value of the condenser circulation system, and adjust the backflushing frequency of the condenser circulation system according to the real-time differential pressure value.

[0036] like Figure 1 As shown, in step S1, if the pipeline of the water supply chemical sampling system is not equipped with online monitoring instruments, the corresponding pipeline of the water supply chemical sampling system will be shut down; if the pipeline of the water supply chemical sampling system is equipped with online monitoring instruments and is a required operating line, the corresponding pipeline of the water supply chemical sampling system will remain in operation. If there are two operating pipelines with the same function in the water supply chemical sampling system, both of which are equipped with online monitoring instruments and neither is a required operating line, the two operating pipelines will be switched to operation.

[0037] In a specific embodiment, such as Figure 2 As shown, the condensate pump outlet pipeline 101 before fine treatment, the condensate pump outlet pipeline 102 after fine treatment, the deaerator recirculation water pump outlet pipeline 103, the first main feedwater main pipeline 104, the second main feedwater main pipeline 105, the first main steam pipeline 106, and the steam converter drain pipeline 107 are all equipped with online monitoring instruments and are required to be in operation. However, the second main steam pipeline 108, the first high-pressure heater drain pipeline 109, and the second high-pressure heater drain pipeline are not equipped with online monitoring instruments 110, so these pipelines will be shut down.

[0038] In addition, the outlet pipelines 111 and 112 of the first and second low-pressure heater condensate pumps have the same function, both equipped with online monitoring instruments and neither is required to operate. The outlet pipelines 111 and 112 of the first and second low-pressure heater condensate pumps are switched into operation. Similarly, the outlet pipelines 113 and 114 of the third and fourth high-pressure heater condensate pumps, as well as the outlet pipelines 115 and 116 of the first steam-water separator reheater condensate pump, are all switched into operation.

[0039] In a specific embodiment, after the drainage of the water supply chemical sampling system was optimized, a total of 10 pipelines were put into long-term operation, and 6 pipelines were shut down. Each unit can reduce effluent discharge by approximately 311 m³ per month. 3 .

[0040] like Figure 3As shown, the steam conversion system 2 in step S2 includes a steam converter 21, a sludge tank 22, a water supply line 23, a detection line 24, and a sludge discharge line 25. The steam converter 21 is connected to the inlet of the sludge tank 22 via the water supply line 23. The water supply line 23 is equipped with an electric valve 26 and a manual valve 27. The detection line 24 is connected to the water supply line 23, and the sludge discharge line 25 is connected to the outlet of the sludge tank 22. The detection line 24 is equipped with a water quality detector 28. The steam converter 21 heats the feedwater with main hot steam to generate low-pressure auxiliary steam, which is then distributed by the auxiliary steam distribution system to users in the nuclear island and conventional island. The sludge tank 22 can receive sludge from the steam converter 21. The sludge from the steam converter 21 flows through the electric valve 26 and the manual valve 27 before being discharged into the sludge tank 22. The detection pipeline 24 can be used to detect the water quality of the discharged wastewater, specifically to detect the sodium content in the emissions from the steam conversion system 2 at different time points, establishing a relationship between sodium content and time. Operators can then establish an analytical model based on this relationship to determine the sodium content trend and whether the steam conversion system 2 needs to discharge wastewater. During the operation of the steam conversion system 2, the electric valve 26 remains open.

[0041] like Figure 4As shown, in step S2, if the sodium content is less than a preset threshold and the sodium content change curve fluctuates within a preset range, then the manual valve 27 is closed to stop the discharge. If the sodium content is less than the preset threshold and the sodium content change curve is on an upward trend, or if the sodium content is greater than or equal to the preset threshold, then the manual valve 27 is opened to discharge. It can be understood that the sodium content change curve fluctuating within the preset range indicates that the sodium content change curve is on a stable trend, and the preset range can be set according to the on-site working conditions. An upward trend in the sodium content change curve means that the sodium content is increasing towards the preset threshold, exceeding the preset range. When the steam conversion system 2 is in its initial operating state, the electric valve 26 is set to the open state, the manual valve 27 is set to the closed state, and the sewage tank 22 stops discharging. At this time, the water quality detector 28 continuously monitors the water quality of the discharged wastewater, specifically detecting the sodium content in the discharged wastewater. When the sodium content is less than the preset threshold and the sodium content change curve fluctuates within the preset range, the water quality of the discharged wastewater is in a normal state, and the manual valve 27 remains closed, requiring no discharge. When the sodium content is below a preset threshold and the sodium content change curve is trending upwards, or when the sodium content is greater than or equal to the preset threshold, it indicates that the wastewater quality is abnormal. Manual valve 27 needs to be opened to discharge wastewater, allowing the wastewater tank 22 to continuously discharge wastewater until the sodium content is below the preset threshold and the sodium content change curve fluctuates within a preset range. Then, manual valve 27 is closed. Compared to the previous continuous discharge from the wastewater tank 22, this steam conversion system 2 can significantly reduce the amount of effluent discharged. The electric valve 26 remains open throughout this process.

[0042] Additionally, if the sodium content is less than a preset threshold and the sodium content change curve is trending upward after closing manual valve 27, or if the sodium content is greater than or equal to the preset threshold, then manual valve 27 is opened to discharge pollutants; if the sodium content is less than the preset threshold and the sodium content change curve fluctuates within a preset range after opening manual valve 27, then manual valve 27 is closed to stop discharging pollutants. In step S2, the preset threshold is 3000 μg / kg.

[0043] Furthermore, in step S3, the preset frequency is once every 16 hours, that is, optimizing the original backwashing frequency from once every 8 hours to once every 16 hours to reduce the backwashing water volume. However, after the backwashing frequency of the condenser circulation system is optimized, the real-time differential pressure value may exceed the preset differential pressure value due to factors such as poor water quality during the initial stage of overhaul startup. The backwashing frequency can be adjusted according to the real-time differential pressure value. In this embodiment, the preset differential pressure value is 0.04 MPa.

[0044] like Figure 5As shown, in step S3, if the real-time differential pressure is less than the preset differential pressure, the automatic backwashing frequency of the condenser circulation system is reduced; if the real-time differential pressure is greater than or equal to the preset differential pressure, the backwashing frequency of the condenser circulation system is increased and the backwashing process is initiated until the real-time differential pressure is less than the preset differential pressure, at which point the automatic backwashing frequency is reduced again. Understandably, if the real-time differential pressure is less than the preset differential pressure, it indicates that the condenser circulation system is operating normally, and the automatic backwashing frequency can be further reduced. Conversely, if the real-time differential pressure is greater than or equal to the preset differential pressure, it indicates that the condenser circulation system is operating abnormally, and the backwashing frequency and backwashing process need to be increased to reduce the real-time differential pressure until it is less than the preset differential pressure, at which point the automatic backwashing frequency is reduced again. By reducing the automatic backwashing frequency, the effluent discharge from the condenser circulation system can be reduced accordingly.

[0045] In summary, this method for reducing effluent emissions from the conventional island of a nuclear power plant reduces overall effluent emissions from the conventional island by shutting down some feedwater chemical sampling system pipelines, reducing effluent emissions from the steam conversion system 2, and decreasing the backwashing frequency of the condenser circulation system. This reduces ammonia nitrogen emissions, alleviates environmental monitoring pressure, and improves environmental friendliness. At the same time, the reduction in downstream wastewater discharge allows for further reduction in upstream water production, lowering water production costs and workload, and improving economic efficiency.

[0046] 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 those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for reducing effluent emissions from the conventional island of a nuclear power plant, wherein the conventional island is equipped with a feedwater chemical sampling system, a steam conversion system (2), and a condenser circulation system, characterized in that, Including the following steps: S1: Determine whether the pipeline of the water supply chemical sampling system is put into operation based on whether the pipeline is equipped with online monitoring instruments and whether the pipeline of the water supply chemical sampling system is a necessary operating line; S2: Detect the sodium content in the emissions of the steam conversion system (2) at different time points, form the relationship between sodium content and time, obtain the sodium content change curve based on the relationship between sodium content and time, and determine whether the steam conversion system (2) should discharge pollutants based on the sodium content and the sodium content change curve. S3: Set the backwashing frequency of the condenser circulation system to a preset frequency, obtain the real-time differential pressure value of the condenser circulation system, and adjust the backwashing frequency of the condenser circulation system according to the real-time differential pressure value.

2. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 1, characterized in that, In step S1, if the pipeline of the water supply chemical sampling system is not equipped with online monitoring instruments, the pipeline of the corresponding water supply chemical sampling system will be shut down. If the pipeline of the water supply chemical sampling system is equipped with online monitoring instruments, and these instruments are required to be in operation, then the pipeline of the corresponding water supply chemical sampling system shall remain in operation.

3. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 1, characterized in that, In step S1, if there are two lines of operating pipelines with the same function in the water supply chemical sampling system, and both lines of operating pipelines are equipped with online monitoring instruments and are not required to operate, then the two lines of operating pipelines are switched to operation.

4. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 1, characterized in that, The steam conversion system (2) includes a steam converter (21), a sewage tank (22), a water pipeline (23), a detection pipeline (24), and a sewage pipeline (25); The steam converter (21) is connected to the inlet of the sewage tank (22) via the water pipeline (23). The water pipeline (23) is equipped with an electric valve (26) and a manual valve (27). The detection pipeline (24) is connected to the water pipeline (23). The sewage pipeline (25) is connected to the outlet of the sewage tank (22). The detection pipeline (24) is equipped with a water quality detector (28).

5. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 4, characterized in that, In step S2, if the sodium content is less than a preset threshold and the sodium content change curve fluctuates within a preset range, then the manual valve (27) is closed to stop the discharge of sewage. If the sodium content is less than the preset threshold and the sodium content change curve is on an upward trend, or if the sodium content is greater than or equal to the preset threshold, then the manual valve (27) is opened to discharge sewage.

6. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 5, characterized in that, In step S2, if the sodium content is less than a preset threshold and the sodium content change curve is on an upward trend after the manual valve (27) is closed, or the sodium content is greater than or equal to the preset threshold, then the manual valve (27) is opened to discharge sewage. If the sodium content is less than the preset threshold and the sodium content change curve fluctuates within the preset range after the manual valve (27) is opened, then the manual valve (27) is closed to stop the discharge.

7. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 5, characterized in that, The preset threshold is 3000 μg / kg.

8. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 1, characterized in that, The preset frequency is once every 16 hours.

9. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 1, characterized in that, In step S3, if the real-time differential pressure value is less than the preset differential pressure value, the automatic backwashing frequency of the condenser circulation system is reduced. If the real-time differential pressure value is greater than or equal to the preset differential pressure value, the backwashing frequency of the condenser circulation system is increased and the backwashing process is started until the real-time differential pressure value is less than the preset differential pressure value, and then the automatic backwashing frequency is reduced.

10. The method for reducing effluent emissions from the conventional island of a nuclear power plant according to claim 9, characterized in that, The preset differential pressure value is 0.04 MPa.

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