Treatment device for seawater desalination and heavy salt water recycling

Abstract

The utility model discloses a treatment device for seawater desalination and heavy salt water recycling, which comprises a pretreatment tank, an ultrafiltration filter, reverse osmosis equipment, electrodialysis equipment and cation exchange equipment which are sequentially and unidirectionally connected through pipelines, and lithium extraction equipment and bipolar membrane electroosmosis equipment are connected onto the cation exchange equipment; a water inlet of the pretreatment tank is connected with seawater, and a water outlet of the pretreatment tank is connected with the ultrafiltration filter; backwashing water in the ultrafiltration filter enters the pretreatment tank, and effluent of the backwashing water enters reverse osmosis equipment; fresh water generated in the reverse osmosis equipment is recycled, and strong brine generated by the reverse osmosis equipment enters the electrodialysis equipment for further concentration treatment. According to the utility model, the electrodialysis equipment is used for further concentrating strong brine generated by the seawater reverse osmosis treatment equipment, so that the fresh water generation rate of the seawater desalination treatment device is improved, brine with higher concentration is obtained, and resource utilization is facilitated.

Description

Technical Field

[0001] This utility model relates to the technical field of seawater desalination treatment devices, specifically a treatment device for seawater desalination combined with high salinity resource utilization. Background Technology

[0002] With the increasing scarcity of freshwater resources in China, seawater desalination is being used to supplement the freshwater produced in coastal areas. However, seawater desalination systems generate large amounts of concentrated brine, which is almost entirely discharged directly into the sea. This not only causes localized increases in salinity, impacting the marine ecosystem, but also wastes the concentrated brine, and the cost of seawater desalination is relatively high.

[0003] To facilitate seawater treatment, a treatment device that combines seawater desalination with high-salinity resource utilization urgently needs to be disclosed. Utility Model Content

[0004] To solve the above-mentioned technical problems, the technical solution provided by this utility model is: a treatment device for seawater desalination and high salinity resource utilization, comprising a pretreatment tank, an ultrafiltration filter, a reverse osmosis device, an electrodialysis device and a cation exchange device connected in sequence through pipelines, wherein a lithium extraction device and a bipolar membrane electrodialysis device are connected to the cation exchange device.

[0005] The inlet of the pretreatment tank is used to connect to seawater, and its outlet is used to connect to an ultrafiltration filter.

[0006] The backwash water from the ultrafiltration filter enters the pretreatment tank, and its effluent is used to enter the reverse osmosis equipment.

[0007] The fresh water produced in the reverse osmosis equipment is recycled and reused, and the concentrated brine produced is used in the electrodialysis equipment for further concentration treatment.

[0008] The electrodialysis equipment is used to electrodialyze concentrated brine to form dilute brine, and the resulting dilute brine enters the reverse osmosis equipment for further desalination. The concentrate produced by the electrodialysis equipment enters the cation exchange equipment.

[0009] The cation exchange equipment is used to remove scale-like cations from the concentrate, and the treated concentrate enters the lithium extraction equipment and the bipolar membrane electroosmosis equipment.

[0010] The lithium extraction equipment can precipitate the concentrated solution containing scale-removing cations as lithium carbonate to obtain lithium carbonate.

[0011] The bipolar membrane electroosmosis equipment can convert the concentrated solution for removing scale-removing cations into acid and alkali solutions, which can be reused in the pretreatment tank.

[0012] Furthermore, a flocculant is added inside the pretreatment tank, and the seawater undergoes a flocculation reaction through the flocculant to remove large particulate impurities such as sludge, suspended solids, and seaweed from the seawater. The sludge generated in the pretreatment tank is dewatered and then transported off-site for disposal.

[0013] Furthermore, the reverse osmosis equipment is equipped with 2-4 sets of reverse osmosis membranes, which are equidistantly connected inside the reverse osmosis equipment, and the salinity of the freshwater produced by the reverse osmosis equipment is less than 200 mg / L.

[0014] Furthermore, the salt content of the dilute brine produced by the electrodialysis equipment is between 10,000 mg / L and 25,000 mg / L, and the salt content of the concentrate produced by the electrodialysis equipment is between 120,000 mg / L and 200,000 mg / L. The ultrafiltration backwash water of the electrodialysis equipment is sent into the reverse osmosis equipment through a pipeline.

[0015] The advantages of the utility model compared to the prior art are:

[0016] 1. This utility model utilizes electrodialysis equipment to further concentrate the brine produced by the seawater reverse osmosis treatment equipment, which not only improves the freshwater production rate of the seawater desalination treatment device, but also obtains brine with a higher concentration, which is convenient for resource utilization and solves the problem of waste of concentrated brine in the prior art.

[0017] 2. This utility model uses lithium extraction equipment to precipitate and separate lithium ions from the concentrated solution obtained after seawater concentration, thereby obtaining lithium carbonate, which has high economic value and realizes the resource utilization of concentrated brine from seawater desalination.

[0018] 3. The bipolar membrane electroosmosis equipment in this utility model can convert the concentrated solution of scale-removing cations into acid and alkali solutions. The generated acid and alkali solutions can be reused in the pretreatment tank, which reduces the reagent cost of the seawater desalination treatment device. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a treatment device for seawater desalination and high salinity resource utilization according to the present invention.

[0020] Figure 2 This is a schematic diagram of the internal structure of a reverse osmosis device.

[0021] The equipment includes: 1. Pretreatment tank; 2. Ultrafiltration filter; 3. Reverse osmosis equipment; 4. Electrodialysis equipment; 5. Cation exchange equipment; 6. Lithium extraction equipment; and 7. Bipolar membrane electrodialysis equipment. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] The present invention will be described in detail with reference to the accompanying drawings.

[0024] In a specific implementation, this utility model provides a treatment device for seawater desalination and high salinity resource utilization, which includes a pretreatment tank 1, an ultrafiltration filter 2, a reverse osmosis device 3, an electrodialysis device 4 and a cation exchange device 5 connected in a unidirectional manner through pipelines. The cation exchange device 5 is connected to a lithium extraction device 6 and a bipolar membrane electrodialysis device 7.

[0025] The inlet of the pretreatment tank 1 is used to connect to seawater, and its outlet is used to connect to the ultrafiltration filter 2.

[0026] The backwash water in the ultrafiltration filter 2 enters the pretreatment tank 1, and its effluent is used to enter the reverse osmosis equipment 3;

[0027] The fresh water produced in the reverse osmosis equipment 3 is recycled and reused, and the concentrated brine produced is used in the electrodialysis equipment 3 for further concentration treatment.

[0028] The electrodialysis device 3 is used to electrodialyze concentrated brine to form dilute brine. The dilute brine produced enters the reverse osmosis device 3 for further desalination. The concentrate produced by the electrodialysis device 3 enters the cation exchange device 5.

[0029] The cation exchange device 5 is used to remove scale-like cations from the concentrate, and the treated concentrate enters the lithium extraction device 6 and the bipolar membrane electroosmosis device 7.

[0030] The lithium extraction device 6 can precipitate the concentrated solution containing scale-removing cations as lithium carbonate to obtain lithium carbonate.

[0031] The bipolar membrane electroosmosis device 7 can convert the concentrated solution for removing scale-removing cations into acid and alkali solutions, and the generated acid and alkali solutions can be reused in the pretreatment tank 1.

[0032] Example:

[0033] The specific working process of this utility model for seawater desalination is as follows:

[0034] The inlet of the pretreatment tank 1 is connected to seawater, and its outlet is used to connect to the ultrafiltration filter 2. The pretreatment tank 1 is used to remove large particulate impurities such as sludge, suspended solids, and seaweed from the seawater. The sludge generated in the pretreatment tank 1 is dewatered and then transported for disposal.

[0035] The outlet of ultrafiltration filter 2 is connected to reverse osmosis equipment 3 for concentration treatment. The freshwater produced by reverse osmosis equipment 3 is recycled, while the concentrated brine produced by reverse osmosis equipment 3 enters electrodialysis equipment 3 for further concentration treatment. The dilute brine produced by electrodialysis equipment 3 enters reverse osmosis equipment 3 for further desalination treatment, and the concentrated solution produced by electrodialysis equipment 3 enters cation exchange equipment 5. Cation exchange equipment 5 removes scale-forming cations such as calcium and magnesium from the concentrated solution. The treated effluent then enters lithium extraction equipment 6 and bipolar membrane electrodialysis equipment 7, respectively. Lithium extraction equipment 6 precipitates lithium ions in the concentrated solution after calcium and magnesium removal by adding sodium carbonate, obtaining lithium carbonate. Bipolar membrane electrodialysis equipment 7 converts the concentrated solution after calcium and magnesium removal into acid and alkali solutions. The generated acid and alkali solutions can be recycled back to pretreatment tank 1.

[0036] In this invention, cation exchange resin is used to further remove the content of hardness ions such as calcium and magnesium in the concentrated brine of the electrodialysis equipment, so as to meet the water quality requirements of the bipolar membrane electrodialysis and lithium extraction equipment.

[0037] The specific implementation method is as follows:

[0038] A certain seawater desalination project is designed to process 800m³ of water. 3 The reverse osmosis system is designed with a recovery rate of 45% per hour, producing 360m³ of freshwater. 3 / h, producing 440m³ of concentrated brine. 3 Currently, concentrated brine is directly discharged into the sea without treatment or recycling. The technology of this invention can be used to treat 440m³ of seawater. 3 The concentrated brine is further concentrated by electrodialysis unit 3, with a designed recovery rate of 70%, producing 308m³ of brine. 3 / h freshwater reuse, producing 132m³ 3 The concentrated solution is fed into the bipolar membrane electrodialysis unit 7 and the lithium extraction unit 6 for resource utilization. The water volume distribution of the concentrated solution in the bipolar membrane electrodialysis unit 7 and the lithium extraction unit 6 is adjusted according to the acid and alkali consumption of the reverse osmosis equipment and the price of lithium carbonate to obtain the most efficient concentrated solution resource utilization scheme. Taking all the concentrated solution as being processed in the lithium extraction unit 6 as an example, the lithium carbonate production reaches 430 g / h. Based on an annual utilization of 6000 hours, the annual lithium carbonate production is 2.58 tons; based on a lithium carbonate price of 80,000 yuan / ton, the annual sales revenue of lithium carbonate is 206,400 yuan. This embodiment uses the lithium extraction unit 6 to precipitate and separate lithium ions from the concentrated solution obtained after seawater concentration to obtain lithium carbonate, which has high economic value and realizes the resource utilization of concentrated brine from seawater desalination.

[0039] To facilitate solid-liquid separation of seawater, a flocculant is added inside the pretreatment tank 1. The seawater undergoes a flocculation reaction through the flocculant to remove large particulate impurities such as sludge, suspended solids, and algae from the seawater. The sludge generated in the pretreatment tank 1 is dewatered and then transported off-site for disposal.

[0040] To facilitate reverse osmosis of seawater, the reverse osmosis device 3 is equipped with 2-4 sets of reverse osmosis membranes. These membranes are equidistantly spaced within the device, and the freshwater produced by the reverse osmosis device 3 has a salinity of less than 200 mg / L. This arrangement of multiple reverse osmosis membranes not only enhances the seawater reverse osmosis treatment effect but also facilitates the disassembly and replacement of the membranes.

[0041] As a further explanation of this utility model, the salt content of the dilute brine produced by the electrodialysis device 3 is between 10,000 mg / L and 25,000 mg / L, the salt content of the concentrate produced by the electrodialysis device 3 is between 120,000 mg / L and 200,000 mg / L, and the ultrafiltration backwash water of the electrodialysis device 3 is sent into the reverse osmosis device 3 through a pipeline.

[0042] In order to reduce the calcium and magnesium ion content in the cation exchange effluent, the cation exchange equipment 5 removes scale-causing cations from the concentrate through cation exchange resin, reducing the calcium and magnesium ion content in the treated effluent to less than 0.1 mg / L. The scale-causing cations include calcium and magnesium ions from seawater.

[0043] In order to reduce the operating cost of seawater desalination, the acid solution used for regenerating the cation exchange resin inside the cation exchange device 5 can be the acid solution generated by the bipolar membrane electroosmosis device 7, and the calcium and magnesium ion content in the effluent of the cation exchange device 5 is reduced to less than 0.1 mg / L.

[0044] As a further explanation of this utility model, the acid concentration after conversion by the bipolar membrane electroosmosis equipment 7 reaches 12%-15%, and the alkali concentration reaches 10%-15%.

[0045] In order to realize the resource utilization of concentrated brine from seawater desalination, the lithium extraction equipment 6 precipitates lithium ions in the concentrate as lithium carbonate by adding sodium carbonate. The sodium carbonate solution is in excess and the pH of the reaction solution is adjusted to 10-11. The precipitated lithium carbonate is dehydrated and dried to obtain a lithium carbonate product with a purity of more than 85%.

[0046] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A treatment device for seawater desalination combined with high-salinity resource utilization, characterized in that: The system includes a pretreatment tank (1), an ultrafiltration filter (2), a reverse osmosis device (3), an electrodialysis device (4), and a cation exchange device (5) connected in a unidirectional manner via pipelines. The cation exchange device (5) is connected to a lithium extraction device (6) and a bipolar membrane electrodialysis device (7). The inlet of the pretreatment tank (1) is used to connect to seawater, and its outlet is used to connect to the ultrafiltration filter (2). The backwash water in the ultrafiltration filter (2) enters the pretreatment tank (1), and its effluent is used to enter the reverse osmosis equipment (3); The fresh water produced in the reverse osmosis equipment (3) is recycled and reused, and the concentrated brine produced is used to enter the electrodialysis equipment (3) for further concentration treatment; The electrodialysis equipment (3) is used to electrodialyze concentrated brine to form dilute brine. The dilute brine produced enters the reverse osmosis equipment (3) for further desalination. The concentrate produced by the electrodialysis equipment (3) enters the cation exchange equipment (5). The cation exchange device (5) is used to remove scale cations from the concentrate, and the treated concentrate enters the lithium extraction device (6) and the bipolar membrane electroosmosis device (7); The lithium extraction equipment (6) can precipitate the concentrated solution containing scale-removing cations as lithium carbonate to obtain lithium carbonate; The bipolar membrane electroosmosis equipment (7) can convert the concentrated solution for removing scale-removing cations into acid and alkali solutions, and the generated acid and alkali solutions can be reused in the pretreatment tank (1).

2. The treatment device for seawater desalination and high-salinity resource utilization according to claim 1, characterized in that: The pretreatment tank (1) contains flocculants, and seawater undergoes a flocculation reaction through the flocculants to remove large particulate impurities such as sludge, suspended solids, and seaweed from the seawater. The sludge generated in the pretreatment tank (1) is dewatered and then transported off-site for disposal.

3. The treatment device for seawater desalination and high-salinity resource utilization according to claim 2, characterized in that: The reverse osmosis device (3) is equipped with 2-4 sets of reverse osmosis membranes, which are equidistantly connected inside the reverse osmosis device (3). The salt content of the fresh water produced by the reverse osmosis device (3) is less than 200 mg / L.

4. The treatment device for seawater desalination and high-salinity resource utilization according to claim 1, characterized in that: The dilute brine produced by the electrodialysis equipment (3) has a salt content of 10,000 mg / L-25,000 mg / L, and the concentrated solution produced by the electrodialysis equipment (3) has a salt content of 120,000 mg / L-200,000 mg / L. The ultrafiltration backwash water of the electrodialysis equipment (3) is sent into the reverse osmosis equipment (3) through a pipeline.

5. The treatment device for seawater desalination and high-salinity resource utilization according to claim 1, characterized in that: The cation exchange device (5) removes scale-causing cations from the concentrate using cation exchange resin, reducing the calcium and magnesium ion content in the treated water to less than 0.1 mg / L. The scale-causing cations include calcium and magnesium ions from seawater.

6. The treatment device for seawater desalination and high-salinity resource utilization according to claim 5, characterized in that: The acid solution used for regenerating the cation exchange resin inside the cation exchange device (5) can be the acid solution generated by the bipolar membrane electroosmosis device (7), and the calcium and magnesium ion content in the effluent of the cation exchange device (5) is reduced to less than 0.1 mg / L.

7. The treatment device for seawater desalination and high-salinity resource utilization according to claim 1, characterized in that: The acid concentration after conversion by the bipolar membrane electroosmosis equipment (7) reaches 12%-15%, and the alkali concentration reaches 10%-15%.

8. The treatment device for seawater desalination and high-salinity resource utilization according to claim 1, characterized in that: The lithium extraction equipment (6) precipitates lithium ions in the concentrate as lithium carbonate by adding sodium carbonate. The sodium carbonate solution is in excess and the pH of the reaction solution is adjusted to 10-11. The precipitated lithium carbonate is dehydrated and dried to obtain a lithium carbonate product with a purity of more than 85%.

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