Nuclear power overhaul sewage treatment system based on electrochemical technology

Abstract

The utility model relates to the technical field of nuclear power overhaul sewage treatment, and particularly discloses a nuclear power overhaul sewage treatment system based on an electrochemical technology, which comprises a circulating water tank, the circulating water tank is connected with a wastewater collecting tank through a first pipeline, and a lifting pump A is mounted on the first pipeline; the circulating water tank is connected with the membrane filtering device through a second pipeline, a lifting pump B is mounted on the second pipeline, and the membrane filtering device is connected with the backwashing water collecting tank through a third pipeline; and the circulating water tank is connected with a conductivity monitor and ammonia nitrogen online monitoring equipment. The system is high in integration level and intelligent in control, can efficiently treat nuclear power overhaul wastewater, and has the characteristics of good environmental safety, strong applicability and mobility, stable treatment effect, high automation control degree and convenience in management and operation.

Description

Technical Field

[0001] This utility model relates to the field of nuclear power plant maintenance wastewater treatment technology, specifically a nuclear power plant maintenance wastewater treatment system based on electrochemical technology. Background Technology

[0002] In recent years, with the continuous development of industrial production, the technology in China's nuclear power field has also been continuously improving and maturing. my country currently ranks among the world's top countries in both the number of operational and under-construction nuclear power plants. The construction and operation of a large number of nuclear power plants inevitably brings with it environmental issues related to the treatment of wastewater, waste gas, and waste residue. Among these, wastewater mainly falls into two categories: high-, medium-, and low-level radioactive production wastewater and maintenance wastewater.

[0003] High-level radioactive industrial wastewater mainly originates from spent fuel reprocessing, radioactive material separation, and major nuclear accidents (such as the Fukushima nuclear disaster), containing high concentrations of long-half-lived nuclides. Intermediate- and low-level radioactive industrial wastewater includes main equipment venting water, secondary loop wastewater, and laboratory wastewater, containing mineral oil, boric acid, chemical reagents, and specific nuclides. High-level radioactive industrial wastewater is primarily preserved long-term using cement solidification and glass solidification (borosilicate glass). Common treatment methods for intermediate- and low-level radioactive industrial wastewater include chemical precipitation (removing specific nuclides), physical adsorption (such as activated carbon adsorption), ion exchange (using exchange resins to retain radioactive ions), membrane separation technology (reverse osmosis, electrodialysis), and combined processes.

[0004] Maintenance wastewater mainly originates from equipment maintenance and pipeline cleaning processes. While it typically has low radioactivity levels, it may contain high levels of salt, mineral oil, heavy metals, and suspended solids. Furthermore, its volume is intermittent and its quality fluctuates significantly. Due to the extreme variations in the quality and quantity of unconventional wastewater, the system must possess strong shock resistance; biological methods are clearly unsuitable for its treatment requirements. Domestic research on nuclear power plant maintenance wastewater treatment technologies is limited, and corresponding treatment facilities are also scarce. Patent CN118708995B utilizes machine learning and sensor technology to monitor the composition of nuclear power plant commissioning or maintenance wastewater in real time. It analyzes the data through deep learning and generates visual reports to improve treatment efficiency and safety, but does not cover wastewater treatment processes or equipment. Patent CN118983121A adjusts the pH and charge of wastewater using hydroxides and flocculants, combined with zeolite adsorption, to remove Ag-110m nuclides. However, it also does not address the treatment of maintenance wastewater with low concentrations of COD and high levels of ammonia nitrogen and total nitrogen. Patent CN116282663A employs an integrated air flotation sedimentation device and filtration system to simultaneously remove ammonia nitrogen and phosphorus from wastewater, but it fails to meet the emission standards for low-concentration COD. Therefore, developing a nuclear power plant maintenance wastewater treatment system based on electrochemical technology, considering safety, environmental protection, and cost, is of profound significance for nuclear power plant maintenance wastewater treatment. This paper presents a nuclear power plant maintenance wastewater treatment system based on electrochemical technology. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a nuclear power plant maintenance wastewater treatment system based on electrochemical technology, thereby solving the problems mentioned in the background section.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a nuclear power plant maintenance wastewater treatment system based on electrochemical technology, comprising a circulating water tank, wherein the circulating water tank is connected to a wastewater collection tank via a first pipeline, a booster pump A is installed on the first pipeline, the circulating water tank is connected to a membrane filtration device via a second pipeline, a booster pump B is installed on the second pipeline, and the membrane filtration device is connected to a backwash water collection tank via a third pipeline;

[0007] The circulating water tank is equipped with a conductivity monitor and an online ammonia nitrogen monitoring device.

[0008] As a preferred embodiment of this utility model, a valve A is also installed on the second pipeline, and a fourth pipeline is connected between the valve A and the booster pump B, with one end of the fourth pipeline connected to the circulating water tank.

[0009] As a preferred embodiment of this utility model, the fourth pipeline is equipped with a valve F and an electrocatalytic oxidation device.

[0010] As a preferred embodiment of this utility model, a valve H is installed on the third pipeline of the membrane filtration device.

[0011] As a preferred embodiment of this utility model, a fifth pipeline is connected to the top of the membrane filtration device, a backwash water tank is installed on the fifth pipeline, a backwash pump and valve E are installed on the pipeline between the outlet of the backwash water tank and the inlet of the membrane filtration device, and valve C is installed on the pipeline between the inlet of the backwash water tank and the outlet of the membrane filtration device.

[0012] In a preferred embodiment of this utility model, the fifth pipeline is connected to the external discharge pipeline, and valve B is installed on the external discharge pipeline.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] 1. Compared with biological methods, this system solves the problem of treating unconventional water with drastic changes in water quality and quantity and strong impact that traditional biological methods cannot handle;

[0015] 2. Compared with traditional physical and chemical treatment processes, this system has a much higher treatment efficiency and can simultaneously treat pollutants such as COD, ammonia nitrogen, and total nitrogen without the need to add any chemical agents;

[0016] 3. The equipment in this system occupies a relatively small area, has a high degree of automation, and produces no secondary pollutants. Attached Figure Description

[0017] Figure 1 This is a system diagram of the present invention.

[0018] In the diagram: 1. Wastewater collection tank; 11. Booster pump A;

[0019] 2. Circulating water tank; 21. Booster pump B; 22. Valve F; 23. Electrocatalytic oxidation device; 24. Conductivity monitor; 25. Ammonia nitrogen online monitoring equipment;

[0020] 3. Membrane filtration device; 31. Valve A; 32. Valve B; 33. Valve C; 34. Backwash water tank; 35. Backwash pump; 36. Valve E; 37. Valve H; 38. Backwash water collection tank. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of the present invention.

[0022] Example 1: Please refer to Figure 1 This utility model provides a technical solution: a nuclear power plant maintenance wastewater treatment system based on electrochemical technology, including a circulating water tank 2, which is connected to a wastewater collection tank 1 via a first pipeline. A booster pump A11 is installed on the first pipeline. The circulating water tank 2 is connected to a membrane filter device 3 via a second pipeline. A booster pump B21 is installed on the second pipeline. The membrane filter device 3 is connected to a backwash water collection tank 38 via a third pipeline. The backwash water in the backwash water tank 38 comes from the wastewater that has been treated to meet the standards by the membrane filter device. Pressure transmitters are installed at the front and rear ends of the membrane filter device 3. When the pressure difference reaches a set value, the device backwashing program is started. During backwashing, the backwash pump is started to backwash the membrane filter device. The backwash water enters the backwash water collection tank 34. After the backwash water settles in the backwash water tank 34, the supernatant is transferred back to the wastewater collection tank 1, and the bottom sludge is cleaned regularly.

[0023] The circulating water tank 2 is connected to a conductivity monitor 24 and an online ammonia nitrogen monitoring device 25.

[0024] The second pipeline is also equipped with valve A31. A fourth pipeline is connected between valve A31 and the booster pump B21. One end of the fourth pipeline is connected to the circulating water tank 2.

[0025] The fourth pipeline is equipped with valve F22 and electrocatalytic oxidation device 23, in which the current density is between 100-600A / ㎡.

[0026] Valve H37 is installed on the third pipeline of membrane filtration device 3.

[0027] A fifth pipeline is connected to the top of the membrane filtration device 3. A backwash water tank 34 is installed on the fifth pipeline. A backwash pump 35 and a valve E36 are installed on the pipeline between the outlet of the backwash water tank 34 and the inlet of the membrane filtration device 3. A valve C33 is installed on the pipeline between the inlet of the backwash water tank 34 and the outlet of the membrane filtration device 3.

[0028] The fifth pipeline is connected to the external drainage pipeline, and valve B32 is installed on the external drainage pipeline.

[0029] Working principle: A nuclear power plant maintenance wastewater treatment system based on electrochemical technology. During operation, the system uses a conductivity monitor 24 and an online COD and ammonia nitrogen monitoring device 25 in the circulating water tank 2. When the conductivity is less than 1000 μS / cm, electrolyte is added to the circulating water tank 2. When the COD and ammonia nitrogen exceed the limits, the system is circulated for treatment. Valve A31 is closed, valve F22 is opened, and lift pump B21 is started. The current density of the electrocatalytic oxidation device 23 is controlled between 100-1000 A / m². When both COD and ammonia nitrogen meet the standards, valve F22 is closed, valve A31 is opened, and lift pump B21 is started to lift the wastewater to the membrane filtration device 3.

[0030] Pressure transmitters are installed at the front and rear ends of the membrane filtration device 3. When the pressure difference reaches 0.2 MPa, the backwashing program of the device is started. Valves A31, B32 and C33 are closed, valves D36 and E37 are opened, and the backwashing pump 35 is started to backwash the membrane filtration device 3. The backwashed water enters the backwash water collection tank 38, where it is allowed to settle. The supernatant is then transferred back to the wastewater collection tank 1, and the bottom sludge is cleaned regularly.

[0031] The specific steps for treating wastewater using a nuclear power plant maintenance wastewater treatment system based on electrochemical technology are as follows:

[0032] Step 1: Use wastewater collection tank 1 to collect and store the maintenance wastewater generated during maintenance;

[0033] Step 2: Use booster pump A11 to lift the wastewater to the circulating water tank 2 of the electrocatalytic oxidation unit. In the circulating water tank 2, COD and ammonia nitrogen are monitored by online monitoring equipment. The results determine whether the electrocatalytic oxidation device needs to be used for treatment. If treatment is required, the circulation process is opened, and the parameters of the conductivity meter determine whether electrolyte needs to be added. If both COD and ammonia nitrogen meet the standards, booster pump B21 is used to lift the wastewater to the membrane filtration unit through valve control.

[0034] When the electrocatalytic oxidation device is working, the conductivity needs to be greater than 1000 μS / cm, the current density of the device should be controlled between 100-1000 A / m², and the COD of the treated wastewater should be less than 50 mg / L and the ammonia nitrogen should be less than 5 mg / L.

[0035] Step 3: Use membrane filtration device 3 to further filter the wastewater to remove suspended solids and discharge it in compliance with standards;

[0036] Pressure transmitters are installed at both ends of the membrane filtration device. When the pressure difference reaches 0.2 MPa, the program is started and the backwash pump is used to backwash the device. The backwash wastewater enters the backwash water collection tank. After the wastewater in the backwash water collection tank is allowed to settle, the clear liquid is returned to the wastewater collection tank for treatment, and the sludge at the bottom is treated regularly.

[0037] Example 2: During the maintenance period of a nuclear power plant, approximately 3m³ of electricity is generated daily. 3 The maintenance wastewater in the storage tank required water quality analysis and treatment before discharge. This system was used for treatment, with sodium chloride as the added electrolyte and a conductivity of 1500 μS / cm. The electrocatalytic oxidation unit had a current density of 600 A / m² and a processing capacity of 500 L / h. The membrane filtration unit had a membrane flux of 8000 L / h, and the overall system processing capacity was ≥500 L / h. Approximately 100 m³ of wastewater was treated in this instance. 3 During the process, the wastewater before and after treatment was analyzed, and the results are as follows:

[0038] index unit Before processing After processing COD mg / L 152～184 ＜20 <![CDATA[NH3-N]]> mg / L 62～76 ＜1

[0039] The above embodiments merely illustrate the implementation of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model.

Claims

1. A nuclear power plant maintenance wastewater treatment system based on electrochemical technology, comprising a circulating water tank (2), characterized in that: The circulating water tank (2) is connected to the wastewater collection tank (1) through a first pipeline, on which a booster pump A (11) is installed. The circulating water tank (2) is connected to the membrane filter device (3) through a second pipeline, on which a booster pump B (21) is installed. The membrane filter device (3) is connected to the backwash water collection tank (38) through a third pipeline. The circulating water tank (2) is connected to a conductivity monitor (24) and an online ammonia nitrogen monitoring device (25).

2. The electrochemical technology based nuclear power plant maintenance sewage treatment system according to claim 1, characterized in that: A valve A (31) is also installed on the second pipeline. A fourth pipeline is connected between the valve A (31) and the booster pump B (21). One end of the fourth pipeline is connected to the circulating water tank (2).

3. The electrochemical technology based nuclear power plant maintenance sewage treatment system according to claim 2, characterized in that: The fourth pipeline is equipped with valve F (22) and electrocatalytic oxidation device (23).

4. The electrochemical technology based nuclear power plant maintenance sewage treatment system according to claim 1, characterized in that: A valve H (37) is installed on the third pipeline of the membrane filtration device (3).

5. The electrochemical technology based nuclear power plant maintenance sewage treatment system according to claim 1, characterized in that: The top of the membrane filtration device (3) is connected to a fifth pipeline, on which a backwash water tank (34) is installed. A backwash pump (35) and a valve E (36) are installed on the pipeline between the outlet of the backwash water tank (34) and the inlet of the membrane filtration device (3). A valve C (33) is installed on the pipeline between the inlet of the backwash water tank (34) and the outlet of the membrane filtration device (3).

6. The electrochemical technology based nuclear power plant maintenance sewage treatment system according to claim 5, characterized in that: The fifth pipeline is connected to the external discharge pipeline, and valve B (32) is installed on the external discharge pipeline.

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