Desalted water production system of nuclear power plant

Abstract

The utility model relates to the field of desalted water equipment, in particular to a desalted water production system of a nuclear power plant. The utility model relates to a desalted water production system for a nuclear power plant, which comprises a nuclear power plant cooling water collection tank, an ozone oxidation tower, a flocculation sedimentation tank, a multi-medium filter, an activated carbon / resin filter, a desalted seawater collection tank, a roll-type ultrafiltration energy recovery device, a roll-type ultrafiltration device, a reverse osmosis energy recovery device and a reverse osmosis device which are sequentially arranged, the device comprises an anion exchanger, a cation exchanger, a mixed bed and a demineralized water collecting tank.

Description

Technical Field

[0001] The utility model relates to the field of demineralized water equipment, and particularly to a demineralized water production system for nuclear power plants. Background Technique

[0002] As an important part of China's electric power, nuclear power plants have made important contributions to China's energy structure adjustment and economic development. However, the operation of nuclear power plants requires a large amount of water resources, and the most important of which is demineralized water. Demineralized water refers to the water that has undergone a series of treatments and processing on ordinary tap water or other water sources to meet the requirements of nuclear power plant water use. In nuclear power plants, demineralized water is mainly used in cooling systems, fire protection systems, washing systems, water production systems, etc., and the purity and stability of the water quality must be ensured. Nuclear power plants have very high requirements for the water quality of demineralized water because impurities in the water will cause harm to the equipment and operation of nuclear power plants. For example, cations in the water will scale in the heat exchanger, affecting the heat transfer effect and shortening the equipment life; anions in the water will cause corrosion in pipelines and equipment, reducing the reliability of the equipment; organic matter and microorganisms in the water will breed bacteria, polluting the water quality and affecting the health of personnel. Therefore, nuclear power plants need to strictly monitor and control demineralized water to ensure that its water quality meets the requirements. The production process of demineralized water in nuclear power plants usually includes multi-step filtration, chemical treatment, adsorption, ion exchange, etc. to remove impurities in the water, such as suspended solids, organic matter, microorganisms, dissolved salts, etc. Currently, Chinese nuclear power plants mainly use reverse osmosis technology to produce demineralized water. Nuclear power plants are of great significance in terms of safety, economy, and environmental protection, and demineralized water is one of the important guarantees for the operation of nuclear power plants, and its quality is directly related to the safety and reliability of nuclear power plants. Therefore, nuclear power plants need to strictly manage and control the production and use of demineralized water to ensure that its water quality meets the requirements. The production of demineralized water is even more strict. While ensuring excellent water quality, the stability of its water production must also be ensured. Therefore, it is very important to design a nuclear power plant demineralized water production system that resists water quality fluctuations.

[0003] CN 218893556 U has proposed a high-utilization-rate demineralized water production system, which includes a raw water tank, a heating device, an ultrafiltration device, a reverse osmosis device, and a mixed bed device connected in sequence by pipelines and pumps, and an emission reduction process is added to improve the water utilization rate of the system. Although this method meets the requirements for producing demineralized water from industrial incoming water, when the incoming water becomes recycled water or cooling water after use, the water quality fluctuation will affect the produced water quality, and the energy consumption in the whole system is relatively high.

[0004] In summary, the existing patents have the following problems: 1. High energy consumption and cost: Traditional desalinated water production technologies, such as multi-stage flash evaporation and multi-stage membrane concentration, although they can effectively remove salts in water, have high energy consumption and large equipment investment, resulting in relatively high overall operating costs. 2. Insufficient stability of produced water quality: When the raw water in the desalinated water system fluctuates in quality, it is easy to affect the produced desalinated water, making it difficult to meet the high standards of water quality required by high-end users such as nuclear power plants. 3. Single treatment water source. In traditional desalinated water systems in nuclear power plants, usually single factory-supplied water or seawater desalinated water is used as the raw water. Treating it singly without recycling will consume a large amount of energy and fresh water resources. 4. Improper treatment of regeneration wastewater: In some desalinated water production processes, wastewater may be generated during the regeneration process. If not properly treated, it will cause secondary pollution to the environment. The present invention may optimize the regeneration process and wastewater treatment process, reduce the generation amount of regeneration wastewater, and effectively treat the generated wastewater to reduce the impact on the environment. Summary of the Invention

[0005] The present invention aims to provide a desalinated water production system for nuclear power plants, and the specific solution is as follows:

[0006] A desalinated water production system for nuclear power plants includes a nuclear power plant cooling water collection pool, an ozone oxidation tower, a flocculation sedimentation tank, a multi-media filter, an activated carbon / resin filter, a seawater desalinated water collection pool, a spiral ultrafiltration energy recovery device, a spiral ultrafiltration device, a reverse osmosis energy recovery device, a reverse osmosis device, an anion exchanger, a cation exchanger, a mixed bed, and a desalinated water collection pool, which are arranged in sequence.

[0007] One end of the spiral ultrafiltration energy recovery device is connected to the nuclear power plant cooling water collection pool through a pipeline, and the other end of the spiral ultrafiltration energy recovery device is connected to the seawater desalinated water collection pool through a pipeline. Both the nuclear power plant cooling water collection pool and the seawater desalinated water collection pool are raw water storage pools for desalinated water production.

[0008] The spiral ultrafiltration energy recovery device and the spiral ultrafiltration device are connected through a feed pipeline and a reflux pipeline.

[0009] The reverse osmosis energy recovery device and the reverse osmosis device are connected through a feed pipeline and a reflux pipeline.

[0010] The reverse osmosis energy recovery device is connected to the seawater desalinated water collection pool through a pipeline.

[0011] An electrodialysis device is provided between the reverse osmosis device and the anion exchanger.

[0012] The electrodialysis device is connected to the multi-media filter and the seawater desalinated water collection pool through pipelines.

[0013] The present utility model has the following advantages:

[0014] 1. By introducing innovative measures such as the combination of reverse osmosis and electrodialysis technologies, and energy recovery devices, the energy consumption and cost of desalted water production are effectively reduced. In addition, according to the water quality, the water to be treated can be selected to directly enter the ion exchanger by skipping the electrodialysis device, reducing energy loss.

[0015] 2. Through the method of separately treating different water sources, the circulating water and cooling water are subjected to multi-stage pretreatment, and then mixed with the high-quality seawater desalinated water, which is beneficial to maintaining the stability of the produced water quality.

[0016] 3. Using the cooling water of nuclear power plants and seawater desalinated water as the two types of raw water to produce desalted water greatly reduces the supply of seawater desalinated water. At the same time, a corresponding pretreatment process for the cooling water of nuclear power plants is set up to effectively recycle the cooling water.

[0017] 4. By optimizing the regeneration process and wastewater treatment process, the generation amount of regeneration wastewater is reduced, and the wastewater generated by different devices is returned to the corresponding treatment stage or reused as cleaning water, effectively improving the water utilization rate of the system and avoiding secondary pollution to the environment. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of a desalted water production system for a nuclear power plant of the present utility model;

[0019] Wherein the reference numerals: 1 - ozone oxidation tower; 2 - flocculation sedimentation tank; 3 - multi-media filter; 4 - activated carbon / resin filter; 5 - spiral ultrafiltration energy recovery device; 6 - spiral ultrafiltration device; 7 - reverse osmosis energy recovery device; 8 - reverse osmosis device; 9 - electrodialysis device; 10 - anion exchanger; 11 - cation exchanger; 12 - mixed bed; 13 - cooling water collection pool of nuclear power plant; 14 - seawater desalinated water collection pool; 15 - desalted water collection pool. Detailed Embodiments

[0020] The following is further described in conjunction with Figure 1 for further illustration:

[0021] A desalted water production system for a nuclear power plant includes a cooling water collection pool 13 of a nuclear power plant, an ozone oxidation tower 1, a flocculation sedimentation tank 2, a multi-media filter 3, an activated carbon / resin filter 4, a seawater desalinated water collection pool 14, a spiral ultrafiltration energy recovery device 5, a spiral ultrafiltration device 6, a reverse osmosis energy recovery device 7, a reverse osmosis device 8, an anion exchanger 10, a cation exchanger 11, a mixed bed 12, and a desalted water collection pool 15 arranged in sequence.

[0022] One end of the spiral ultrafiltration energy recovery device 5 is connected to the nuclear power plant cooling water collection tank 13 through a pipeline, and the other end of the spiral ultrafiltration energy recovery device 5 is connected to the desalinated water collection tank 14 through a pipeline. Both the nuclear power plant cooling water collection tank 13 and the desalinated water collection tank 14 are raw water storage tanks for desalted water production.

[0023] The spiral ultrafiltration energy recovery device 5 and the spiral ultrafiltration device 6 are connected through a feed pipeline and a reflux pipeline.

[0024] The spiral ultrafiltration energy recovery device 5 and the nuclear power plant cooling water collection tank 13 are connected through a pipeline.

[0025] The reverse osmosis energy recovery device 7 and the reverse osmosis device 8 are connected through a feed pipeline and a reflux pipeline.

[0026] The reverse osmosis energy recovery device 7 and the desalinated water collection tank 14 are connected through a pipeline.

[0027] An electrodialysis device 9 is provided between the reverse osmosis device 8 and the anion exchanger 10.

[0028] The electrodialysis device 9 is connected to the multi-media filter 3 and the desalinated water collection tank 14 through pipelines.

[0029] The nuclear power plant desalted water production process system uses two types of raw water to produce desalted water. One type is the cooling water used for cooling the nuclear power plant reactor and other equipment. After flowing through various equipment in the nuclear power plant, substances such as colloids, suspended solids, and radioactive metal ions may exist in the water, and certain pretreatment is required. The other type is desalinated water. After passing through the seawater desalination system, the conductivity of seawater can be reduced to below 100 μS / cm, and the salt ion concentration of the desalinated water still needs to be further reduced for reuse as desalted water. After certain treatments, the two types of raw water are mixed and uniformly treated to prepare desalted water. The specific steps are as follows.

[0030] Step 1: The cooling water used to cool various equipment in the nuclear power plant is uniformly collected into device 13 (nuclear power plant cooling water collection tank 13) after use, and preliminary pretreatment is prepared.

[0031] Step 2: Device 13 (nuclear power plant cooling water collection tank 13) is connected to device 1 (ozone oxidation tower 1) through a pipeline, and the strong oxidizing property of ozone is used to perform advanced oxidation treatment on the cooling water to destroy and remove pollutants such as refractory organic matter, chromaticity, and odor in the water.

[0032] Step 3: The water outlet pipe of Device 1 (Ozone Oxidation Tower 1) is connected to Device 2 (Flocculation Sedimentation Tank 2). The cooled water after advanced oxidation first enters the coagulation system. The coagulation agents (such as polyferric sulfate and polyaluminum chloride) are prepared into solutions with certain concentrations and then added to the cooled water. After the agents are added to the wastewater, hydrolysis occurs, generating hetero-charge colloids, which contact with the colloids and suspended solids in the water to form flocs. The mixing process is completed in about 10 - 30 seconds, and hydraulic or mechanical stirring methods can be used. After the wastewater is dosed, mixed, and reacted, the flocculation process is completed, and it enters the sedimentation tank for sediment-water separation. The sedimentation tank has various forms such as horizontal flow, radial flow, vertical flow, and inclined plate. The coagulation sedimentation device adds coagulants and flocculants to the cooled water, causing harmful substances such as suspended solids, chromaticity, and radioactive heavy metal ions in the water to aggregate into larger particles, and then separating them from the water by sedimentation or filtration methods.

[0033] Step 4: The water outlet pipe of Device 2 (Flocculation Sedimentation Tank 2) is connected to Device 3 (Multi-media Filter 3). Device 3 (Multi-media Filter 3) is filled with various types of fillers, which can effectively remove impurities such as suspended solids, colloids, and organic matters in the cooled water, and protect the subsequent membrane modules.

[0034] Step 5: The water outlet pipe of Device 3 (Multi-media Filter 3) is connected to Device 4 (Activated Carbon / Resin Filter 4). The cooled water enters the Activated Carbon / Resin Filter 4. The activated carbon adsorbs and removes organic matters, suspended solids, etc. in the water, while the resin can effectively remove trace radioactive substances and impurities.

[0035] Step 6: The water outlet pipe of Device 4 (Activated Carbon / Resin Filter 4) is connected to Device 14 (Seawater Desalination Water Collection Tank 14). The preliminarily treated cooled water is mixed with the seawater desalination water for further desalination treatment.

[0036] Step 7: The pipe of Device 14 (Seawater Desalination Water Collection Tank 14) is connected to the low-pressure fluid inlet end of Device 5 (Spiral Ultrafiltration Energy Recovery Device 5). The low-pressure fluid outlet pipe of Device 5 (Spiral Ultrafiltration Energy Recovery Device 5) is connected to Device 6 (Spiral Ultrafiltration Device 6). Under the sieving action of spiral ultrafiltration, substances such as residual organic matters and suspended solids in the mixed water can be basically completely removed, improving the water quality and reducing the working burden of the reverse osmosis membrane.

[0037] Step 8: The concentrated water pipe of Device 6 (Spiral Ultrafiltration Device 6) is connected to the high-pressure fluid inlet end of Device 5 (Spiral Ultrafiltration Energy Recovery Device 5). The high-pressure fluid outlet pipe of Device 5 (Spiral Ultrafiltration Energy Recovery Device 5) is connected to Device 13 (Nuclear Power Plant Cooling Water Collection Tank 13). The spiral ultrafiltration concentrated water is recycled to the front end of the pretreatment for further treatment. The energy recovery device converts the pressure energy of the concentrated water generated during the spiral ultrafiltration process into mechanical energy for recycling and reuse, thereby reducing the overall energy consumption of the system.

[0038] Step Nine: Connect the water production end pipeline of Device 6 (Spiral Ultrafiltration Device 6) to the low-pressure fluid inlet end of Device 7 (Reverse Osmosis Energy Recovery Device 7), and connect the low-pressure fluid outlet end pipeline of Device 7 (Reverse Osmosis Energy Recovery Device 7) to Device 8 (Reverse Osmosis Device 8). Under the action of the high-pressure pump and the energy recovery device, the mixed water after spiral ultrafiltration post-treatment enters the reverse osmosis membrane module. Through the selective permeation of the membrane, inorganic salt ions are greatly removed, and high-quality fresh water is produced.

[0039] Step Ten: Connect the concentrated water end pipeline of Device 8 (Reverse Osmosis Device 8) to the high-pressure fluid inlet end of Device 7 (Reverse Osmosis Energy Recovery Device 7), and connect the high-pressure fluid outlet end pipeline of Device 7 (Reverse Osmosis Energy Recovery Device 7) to Device 14 (Seawater Desalination Water Collection Tank 14). The reverse osmosis concentrated water is recycled to the front end of the spiral ultrafiltration for further treatment. The energy recovery device converts the pressure energy of the concentrated water generated during the reverse osmosis process into mechanical energy for recycling and reuse, thereby reducing the overall energy consumption of the system.

[0040] Step Eleven: Connect the water production end pipeline of Device 8 (Reverse Osmosis Device 8) to Device 9 (Electrodialysis Device 9). Depending on the water quality of the reverse osmosis product water, it is selected whether to enter the electrodialysis system to further remove the remaining salts by using the electric field force. The combination of reverse osmosis and electrodialysis can make full use of the advantages of the two technologies to improve the desalination efficiency and water quality.

[0041] Step Twelve: The water production end of Device 8 (Reverse Osmosis Device 8) can be directly connected to Device 10 (Anion Exchanger 10) through a pipeline. Through the exchange action of the strong-base anion resin in the anion exchanger 10, the remaining anions in the water are removed.

[0042] Step Thirteen: Connect the fresh water end pipeline of Device 9 (Electrodialysis Device 9) to Device 10 (Anion Exchanger 10). Through the exchange action of the strong-base anion resin in the anion exchanger 10, the remaining anions in the water are removed.

[0043] Step Fourteen: Connect the concentrated water end pipeline of Device 9 (Electrodialysis Device 9) to Device 2 (Flocculation Sedimentation Tank 2) and Device 3 (Multi-media Filter 3). The electrodialysis concentrated water is used as the cleaning water for the pretreatment device to provide a cleaning function.

[0044] Step Fifteen: Connect the water production end pipeline of Device 10 (Anion Exchanger 10) to Device 11 (Cation Exchanger 11). Through the exchange action of the strong-acid cation resin in the cation exchanger 11, the remaining cations in the water are removed.

[0045] Step Sixteen: Connect the water outlet pipe of Device 11 (cation exchanger 11) to Device 12 (mixed bed 12). After ion exchange, a mixed bed resin is connected in series for final treatment to further ensure water quality. The combination of ion exchange and mixed bed resin can remove trace ions in water and ensure that the water quality of the effluent reaches an extremely high standard.

[0046] Among them, a multi-stage shielding device is set for the cooling water pretreatment device 1 (ozone oxidation tower 1) to device 4 (activated carbon / resin filter 4). Residual radioactive substances in the cooling water, such as cesium, strontium, iodine, etc., are completely removed in device 2 (flocculation sedimentation tank 2) and device 4 (activated carbon / resin filter 4).

[0047] Among them, the filtration speed of device 3 (multi-media filter 3) is controlled within a certain range to avoid a decrease in filtration effect caused by being too fast. Device 4 (activated carbon / resin filter 4) is regularly cleaned and replaced according to the raw water quality and the performance of activated carbon and resin.

[0048] Among them, device 5 (spiral ultrafiltration energy recovery device 5) and device 7 (reverse osmosis energy recovery device 7) are energy recovery devices for the membrane system. A hydraulic turbine type device can be selected to recover the remaining pressure of the concentrated water of spiral ultrafiltration and reverse osmosis. In the energy conversion process of the energy recovery device "pressure energy - mechanical energy - pressure energy", the concentrated water of spiral ultrafiltration and reverse osmosis enters from the high-pressure fluid inlet end of the energy recovery device. Driven by the concentrated water pressure, the impeller contained in this end starts to rotate, and at the same time drives the impeller at the low-pressure fluid end to rotate. The water inlet of spiral ultrafiltration and reverse osmosis is gradually pressurized under the drive of the impeller, reducing a part of the pressure provided by the high-pressure pump, thereby reducing the operating energy consumption. The energy recovery can reach 65 - 80%.

[0049] The utility model has the following advantages:

[0050] 1. Improve the water quality of the produced water: Produce demineralized water with two types of raw water, namely the cooling water of nuclear power plants and seawater desalination water. Set a corresponding pretreatment process for the cooling water and mix it with the seawater desalination water for treatment, effectively ensuring the stability of the incoming water quality. Through the combined process of spiral ultrafiltration, reverse osmosis, electrodialysis, and cation and anion exchangers, the water quality of the produced water can be significantly improved to meet the high-standard water use requirements of nuclear power plants.

[0051] 2. Reduce energy consumption costs: The introduction of energy recovery devices in the process of spiral ultrafiltration and reverse osmosis helps to reduce the energy consumption costs of the system and improve economic benefits. In addition, according to the water quality situation, it is only necessary to select whether the water to be treated passes through the electrodialysis device, which can avoid the consumption of excess energy.

[0052] 3. Improve the utilization rate of water resources: Carry out corresponding treatment on the cooling water of nuclear power plants and produce demineralized water, greatly reducing the supply of external water. At the same time, the concentrated water produced by each device in the demineralized water production system is respectively returned to the front end correspondingly or used as washing water treatment, and the produced wastewater is recycled. This not only reduces the environmental pollution caused by wastewater discharge, but also improves the utilization rate of water resources, contributing to the realization of sustainable development.

[0053] The above content describes the technical principle, beneficial effects and characteristics of the present invention. It should be noted that the above is only the preferred embodiment of the present invention, but not limited by the above embodiments. For those skilled in the technical field to which the present invention belongs, without departing from the content of the present invention, some improvements and optimizations can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A demineralized water production system for nuclear power plants, characterized in that: It includes a nuclear power plant cooling water collection pool, an ozone oxidation tower, a flocculation sedimentation tank, a multi-media filter, an activated carbon / resin filter, a seawater desalination water collection pool, a spiral ultrafiltration energy recovery device, a spiral ultrafiltration device, a reverse osmosis energy recovery device, a reverse osmosis device, an anion exchanger, a cation exchanger, a mixed bed and a demineralized water collection pool which are arranged in sequence.

2. A demineralized water production system for nuclear power plants according to claim 1, characterized in that: One end of the spiral ultrafiltration energy recovery device is connected to the nuclear power plant cooling water collection pool through a pipeline, and the other end of the spiral ultrafiltration energy recovery device is connected to the seawater desalination water collection pool through a pipeline.

3. A demineralized water production system for nuclear power plants according to claim 1, characterized in that: The spiral ultrafiltration energy recovery device and the spiral ultrafiltration device are connected through a feed pipeline and a reflux pipeline.

4. A demineralized water production system for a nuclear power plant according to claim 1, characterized in that: The reverse osmosis energy recovery device and the reverse osmosis device are connected through a feed pipeline and a reflux pipeline.

5. The demineralized water production system of a nuclear power plant according to claim 1, wherein: The reverse osmosis energy recovery device is connected to the seawater desalination water collection pool through a pipeline.

6. The demineralized water production system for nuclear power plants according to claim 1, characterized in that: An electrodialysis device is provided between the reverse osmosis device and the anion exchanger.

7. The demineralized water production system of a nuclear power plant according to claim 6, characterized in that: The electrodialysis device is connected to the multi-media filter and the seawater desalination water collection pool through pipelines.

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