Seawater zero discharge system

Abstract

The utility model provides a seawater zero-discharge system, which relates to the technical field of seawater desalination and discharge, seawater desalination is carried out by utilizing a forward osmosis technology, the forward osmosis has the characteristics of low energy consumption and strong anti-pollution capability, the problem of seawater pollution can be effectively solved, and concentrated seawater is subjected to nano-filtration and refining to obtain purified seawater. The nanofiltration concentrated water has high content of calcium, magnesium, sulfate radicals and other substances, calcium sulfate can be prepared by adding lime, magnesium hydroxide can be prepared by using sodium hydroxide, calcium carbonate can be prepared by using sodium carbonate, chemical substances in the concentrated seawater can be effectively treated, and the quality of the concentrated seawater can be improved. The pollution to the environment is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of seawater desalination and discharge, in particular to a seawater zero-discharge system. Background Art

[0002] Water shortages have become a global issue. With socioeconomic development and population growth, the imbalance between water supply and demand is becoming increasingly prominent. Desalination has gradually become one of the most important technological solutions to address the current global freshwater shortage, and both the technology level and industrial scale of desalination have developed rapidly. Reverse osmosis membrane desalination technology, due to its simple operation, lack of phase change, and low energy consumption, has become one of the mainstream desalination technologies.

[0003] There are currently marine pollution problems in seawater, which can cause pollution of reverse osmosis membranes, thereby affecting the seawater zero discharge system.

[0004] Furthermore, the impact of the desalination process and its products on the ecological environment is becoming an increasingly critical factor. Concentrated seawater, a byproduct of desalination equipment, has a high salinity, a complex chemical composition, and contains other chemicals added during the seawater pretreatment process. Improper treatment can pose a serious threat to the soil, groundwater, surface water, and marine ecosystems. Therefore, the scientific and rational treatment and comprehensive utilization of concentrated seawater are of great significance. In some special regions, such as the Bohai Rim, which lacks open sea areas, this has become a key bottleneck in the development of the desalination industry. Utility Model Content

[0005] The purpose of the utility model is to provide a seawater zero discharge system to alleviate the technical problems in the prior art that the reverse osmosis technology used to desalinate seawater has poor anti-pollution ability and the concentrated seawater produced as a by-product of the seawater desalination equipment will damage the environment.

[0006] The seawater zero discharge system provided by the utility model includes: a forward osmosis system, a nanofiltration system, a multi-effect evaporation system, a bipolar membrane system and a treatment system;

[0007] The forward osmosis system is used to deliver concentrated seawater, and the forward osmosis system is configured to desalinate the concentrated seawater;

[0008] The forward osmosis system is in communication with the nanofiltration system, and the seawater desalinated by the forward osmosis system can enter the nanofiltration system. The nanofiltration system is configured to purify the desalinated seawater to form nanofiltration product water and nanofiltration concentrated water;

[0009] The multi-effect evaporation system is connected to the nanofiltration system, and the nanofiltration water produced by the nanofiltration system enters the multi-effect evaporation system. The multi-effect evaporation system is configured to evaporate and crystallize the nanofiltration water to form finished salt;

[0010] The treatment system is connected to the nanofiltration system, and the nanofiltration concentrated water generated by the nanofiltration system enters the treatment system. The treatment system is configured to add lime to the nanofiltration concentrated water to produce calcium sulfate, add sodium hydroxide to the nanofiltration concentrated water to produce magnesium hydroxide, and add sodium carbonate to the nanofiltration concentrated water to produce calcium carbonate.

[0011] Further,

[0012] The multiple-effect evaporation system is communicated with the forward osmosis system, and the concentrated brine in the multiple-effect evaporation system can be transported to the forward osmosis system as the draw liquid in the forward osmosis system.

[0013] Further,

[0014] The seawater zero discharge system also includes a bipolar membrane system;

[0015] The bipolar membrane system is in communication with the forward osmosis system, and the diluted draw liquid in the forward osmosis system can enter the bipolar membrane system. The bipolar membrane system is used to convert the draw liquid into acid and alkali.

[0016] Further,

[0017] The treatment system includes a first reaction tank;

[0018] The first reaction tank is connected to the nanofiltration system, and the nanofiltration concentrated water formed by the nanofiltration system can enter the first reaction tank;

[0019] The first reaction tank is configured to be able to be fed with lime so that the lime reacts with the nanofiltration concentrated water to form calcium sulfate.

[0020] Further,

[0021] The treatment system also includes a first sedimentation tank;

[0022] The first precipitation tank is connected to the first reaction tank, and the first precipitation tank is used to filter and precipitate calcium sulfate in the first reaction tank to form a calcium sulfate product.

[0023] Further,

[0024] The treatment system also includes a second reaction tank;

[0025] The second reaction tank is connected to the first precipitation tank, and the solution in the first precipitation tank can enter the second reaction tank;

[0026] The second reaction tank is configured to be able to input sodium hydroxide so that the sodium hydroxide reacts with the nanofiltration concentrated water to form magnesium hydroxide.

[0027] Further,

[0028] The treatment system also includes a second sedimentation tank;

[0029] The second precipitation tank is communicated with the second reaction tank, and the second precipitation tank is used to filter and precipitate the magnesium hydroxide in the second reaction tank to form a magnesium hydroxide product.

[0030] Further,

[0031] The treatment system also includes a third reaction tank;

[0032] The third reaction tank is connected to the second precipitation tank, and the solution in the second precipitation tank can enter the third reaction tank;

[0033] The third reaction tank is configured to be able to input sodium carbonate so that the sodium carbonate reacts with the nanofiltration concentrated water to form calcium carbonate.

[0034] Further,

[0035] The treatment system also includes a third sedimentation tank;

[0036] The third sedimentation tank is connected to the third reaction tank, and the third sedimentation tank is used to filter and precipitate the calcium carbonate in the third reaction tank to form a calcium carbonate product.

[0037] Further,

[0038] The third sedimentation tank is connected to the nanofiltration system, and the solution in the third sedimentation tank can enter the nanofiltration system.

[0039] The seawater zero-discharge system provided by the utility model utilizes forward osmosis technology to desalinate seawater. Forward osmosis has the characteristics of low energy consumption and strong anti-pollution ability, which can effectively solve the problem of seawater pollution. After the concentrated seawater is refined by nanofiltration, it enters the multi-effect evaporation system for evaporation and crystallization to obtain finished salt, which is sold as edible salt. In addition, the nanofiltration concentrated water has high levels of calcium, magnesium, sulfate and other substances. Calcium sulfate can be produced by adding lime, magnesium hydroxide can be produced by using sodium hydroxide, and calcium carbonate can be produced by using sodium carbonate. Chemical substances in the concentrated seawater are effectively treated to avoid pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1This is an overall flow chart of the seawater zero discharge system provided in an embodiment of the present utility model.

[0042] Icons: 1-Forward osmosis system; 2-Nanofiltration system; 3-Multi-effect evaporation system; 4-Bipolar membrane system; 5-First reaction tank; 6-First sedimentation tank; 7-Second reaction tank; 8-Second sedimentation tank; 9-Third reaction tank; 10-Third sedimentation tank. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0044] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0046] The following is a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0047] like Figure 1As shown, the seawater zero discharge system provided in this embodiment includes: a forward osmosis system 1, a nanofiltration system 2, a multi-effect evaporation system 3, a bipolar membrane system 4 and a treatment system. The forward osmosis system 1 is used to release concentrated seawater. Specifically, the concentrated seawater enters the sand filtration system after flocculation and sedimentation. The sand filtration system filters the sand and gravel in the concentrated seawater. After filtration, the concentrated seawater enters the forward osmosis system 1. The forward osmosis system 1 uses forward osmosis technology to desalinate the concentrated seawater. Forward osmosis technology has the characteristics of low energy consumption and strong anti-pollution ability, which can effectively solve the problem of seawater pollution.

[0048] The forward osmosis system 1 is connected to the nanofiltration system 2. The seawater desalinated by the forward osmosis system 1 can enter the nanofiltration system 2. The nanofiltration system 2 can refine the desalinated seawater to form nanofiltration product water and nanofiltration concentrated water.

[0049] The multi-effect evaporation system 3 is connected to the nanofiltration system 2. The nanofiltration water produced by the nanofiltration system 2 enters the multi-effect evaporation system 3. The multi-effect evaporation system 3 evaporates and crystallizes the nanofiltration water to form finished salt, which is sold as edible salt.

[0050] The treatment system is connected to the nanofiltration system 2, and the nanofiltration concentrated water formed by the nanofiltration system 2 enters the treatment system. The nanofiltration concentrated water contains high levels of calcium, magnesium, sulfate and other substances. The treatment system is configured to add lime to the nanofiltration concentrated water to produce calcium sulfate, add sodium hydroxide to the nanofiltration concentrated water to produce magnesium hydroxide, and add sodium carbonate to the nanofiltration concentrated water to produce calcium carbonate.

[0051] In an optional embodiment, the multiple-effect evaporation system 3 is connected to the forward osmosis system 1, and the concentrated brine in the multiple-effect evaporation system 3 can be transported to the forward osmosis system 1 as the draw liquid in the forward osmosis system 1, thereby improving the forward osmosis efficiency.

[0052] In an optional embodiment, the seawater zero discharge system also includes a bipolar membrane system 4; the bipolar membrane system 4 is connected to the forward osmosis system 1, and the diluted draw liquid of the forward osmosis system 1 enters the bipolar membrane system 4. The bipolar membrane system 4 is used to convert the draw liquid into acid and alkali to form hydrochloric acid and sodium hydroxide.

[0053] Regarding the structure of the processing system, specifically:

[0054] The treatment system includes a first reaction tank 5; the first reaction tank 5 is connected to the nanofiltration system 2, and the nanofiltration concentrated water formed by the nanofiltration system 2 can enter the first reaction tank 5; lime is added to the first reaction tank 5 to allow the lime to react with the nanofiltration concentrated water to form calcium sulfate.

[0055] The treatment system further includes a first sedimentation tank 6 ; the first sedimentation tank 6 is connected to the first reaction tank 5 , and the first sedimentation tank 6 filters and precipitates the solids and liquids flowing into the first sedimentation tank 6 from the first reaction tank 5 to form a calcium sulfate product.

[0056] The treatment system also includes a second reaction tank 7; the second reaction tank 7 is connected to the first sedimentation tank 6, and the solution in the first sedimentation tank 6 can enter the second reaction tank 7; sodium hydroxide is added to the second reaction tank 7 to react with the nanofiltration concentrated water to form magnesium hydroxide.

[0057] The treatment system further includes a second sedimentation tank 8 ; the second sedimentation tank 8 is connected to the second reaction tank 7 , and the second sedimentation tank 8 filters and precipitates the solids and liquids flowing into the second sedimentation tank 8 from the second reaction tank 7 to form a magnesium hydroxide product.

[0058] The treatment system also includes a third reaction tank 9; the third reaction tank 9 is connected to the second sedimentation tank 8, and the solution in the second sedimentation tank 8 can enter the third reaction tank 9; sodium carbonate is added to the third reaction tank 9 to react with the nanofiltration concentrated water to form calcium carbonate.

[0059] The treatment system further includes a third sedimentation tank 10 ; the third sedimentation tank 10 is connected to the third reaction tank 9 , and the third sedimentation tank 10 filters and precipitates the solids and liquids flowing into the third sedimentation tank 10 from the third reaction tank 9 to form a calcium carbonate product.

[0060] The third sedimentation tank 10 is connected to the nanofiltration system 2. The solution in the third sedimentation tank 10 can enter the nanofiltration system 2, so that the solution returns to the nanofiltration system 2 and is refined again.

[0061] The utility model provides a zero-discharge seawater system, and the specific process is as follows: a forward osmosis system 1 is used to desalinate seawater. Forward osmosis has the characteristics of low energy consumption and strong anti-pollution ability, which can effectively solve the problem of seawater pollution; the concentrated seawater is then refined by a nanofiltration system 2 and enters a multi-effect evaporation system 3 for evaporation and crystallization to obtain finished salt, which is sold as edible salt; part of the concentrated brine in the multi-effect evaporation system 3 can be used as the draw liquid of the forward osmosis system 1, thereby improving the forward osmosis efficiency; the diluted draw liquid enters a bipolar membrane system 4 to prepare acid and alkali, and returns to the system; the nanofiltration system 2 forms a nanofiltration concentrated water with high content of calcium, magnesium, sulfate and other substances, which can be used to prepare calcium sulfate by adding lime, magnesium hydroxide by using sodium hydroxide, and calcium carbonate by using sodium carbonate.

[0062] The seawater zero discharge system provided by the utility model has the following advantages:

[0063] (1) Using forward osmosis technology to desalinate seawater, which has the characteristics of low energy consumption and strong anti-pollution ability, can effectively solve the problem of seawater pollution.

[0064] (2) The concentrated seawater is refined by nanofiltration and then enters the multi-effect evaporation system 3 for evaporation and crystallization to obtain finished salt, which is sold as edible salt.

[0065] (3) Part of the concentrated brine produced by multi-effect evaporation can be used as the draw solution for forward osmosis, thereby improving the efficiency of forward osmosis. The diluted draw solution enters the bipolar membrane system 4, where it is used to produce acid and alkali, and then returns to the system.

[0066] (4) Nanofiltration concentrated water contains high levels of calcium, magnesium, sulfate and other substances, which can be used to produce calcium sulfate by adding lime, magnesium hydroxide by using sodium hydroxide, and calcium carbonate by using sodium carbonate.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A seawater zero discharge system, characterized in that: include: Forward osmosis system (1), nanofiltration system (2), multiple-effect evaporation system (3), bipolar membrane system (4) and treatment system; The forward osmosis system (1) is used to deliver concentrated seawater, and the forward osmosis system (1) is configured to be able to desalinate the concentrated seawater; The forward osmosis system (1) is connected to the nanofiltration system (2), and the seawater desalinated by the forward osmosis system (1) can enter the nanofiltration system (2). The nanofiltration system (2) is configured to purify the desalinated seawater to form nanofiltration product water and nanofiltration concentrated water; The multi-effect evaporation system (3) is in communication with the nanofiltration system (2), and the nanofiltration product water generated by the nanofiltration system (2) enters the multi-effect evaporation system (3), and the multi-effect evaporation system (3) is configured to evaporate and crystallize the nanofiltration product water to form finished salt; The treatment system is connected to the nanofiltration system (2), and the nanofiltration concentrated water generated by the nanofiltration system (2) enters the treatment system. The treatment system is configured to be able to add lime to the nanofiltration concentrated water to produce calcium sulfate, add sodium hydroxide to the nanofiltration concentrated water to produce magnesium hydroxide, and add sodium carbonate to the nanofiltration concentrated water to produce calcium carbonate.

2. The seawater zero discharge system according to claim 1, characterized in that: The multiple-effect evaporation system (3) is connected to the forward osmosis system (1), and the concentrated brine in the multiple-effect evaporation system (3) can be transported to the forward osmosis system (1) as the draw liquid in the forward osmosis system (1).

3. The seawater zero discharge system according to claim 2, characterized in that: The seawater zero discharge system further comprises a bipolar membrane system (4); The bipolar membrane system (4) is in communication with the forward osmosis system (1), and the diluted draw liquid in the forward osmosis system (1) can enter the bipolar membrane system (4). The bipolar membrane system (4) is used to convert the draw liquid into acid or alkali.

4. The seawater zero discharge system according to claim 1, characterized in that: The treatment system includes a first reaction tank (5); The first reaction tank (5) is in communication with the nanofiltration system (2), and the nanofiltration concentrated water formed by the nanofiltration system (2) can enter the first reaction tank (5); The first reaction tank (5) is configured to be able to be fed with lime so that the lime reacts with the nanofiltration concentrated water to form calcium sulfate.

5. The seawater zero discharge system according to claim 4, characterized in that: The treatment system further comprises a first sedimentation tank (6); The first precipitation tank (6) is connected to the first reaction tank (5), and the first precipitation tank (6) is used to filter and precipitate calcium sulfate in the first reaction tank (5) to form a calcium sulfate product.

6. The seawater zero discharge system according to claim 5, characterized in that: The treatment system further comprises a second reaction tank (7); The second reaction tank (7) is connected to the first sedimentation tank (6), and the solution in the first sedimentation tank (6) can enter the second reaction tank (7); The second reaction tank (7) is configured to be able to input sodium hydroxide so that the sodium hydroxide reacts with the nanofiltration concentrated water to form magnesium hydroxide.

7. The seawater zero discharge system according to claim 6, characterized in that: The treatment system further comprises a second sedimentation tank (8); The second precipitation tank (8) is connected to the second reaction tank (7), and the second precipitation tank (8) is used to filter and precipitate the magnesium hydroxide in the second reaction tank (7) to form a magnesium hydroxide product.

8. The seawater zero discharge system according to claim 7, characterized in that: The treatment system further comprises a third reaction tank (9); The third reaction tank (9) is connected to the second sedimentation tank (8), and the solution in the second sedimentation tank (8) can enter the third reaction tank (9); The third reaction tank (9) is configured to be able to be fed with sodium carbonate so that the sodium carbonate reacts with the nanofiltration concentrated water to form calcium carbonate.

9. The seawater zero discharge system according to claim 8, characterized in that: The treatment system further comprises a third sedimentation tank (10); The third sedimentation tank (10) is connected to the third reaction tank (9), and the third sedimentation tank (10) is used to filter and precipitate calcium carbonate in the third reaction tank (9) to form a calcium carbonate product.

10. The seawater zero discharge system according to claim 9, characterized in that: The third sedimentation tank (10) is connected to the nanofiltration system (2), and the solution in the third sedimentation tank (10) can enter the nanofiltration system (2).

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