Device and method for preparing industrial desalted water

Abstract

The invention discloses a device and a method for preparing industrial desalted water, and relates to the technical field of industrial desalinization, the device comprises a raw water tank, a heat exchanger, a self-cleaning filter, an ultrafiltration assembly, an ultrafiltration water tank, a reverse osmosis assembly, a reverse osmosis water production tank, a mixed bed and a desalted water tank, a concentrated water recycling module is arranged between the reverse osmosis assembly and the reverse osmosis water producing tank and comprises a reverse osmosis concentrated water collecting tank with a reverse osmosis membrane, a hollow fiber nanofiltration membrane assembly communicated with the reverse osmosis concentrated water collecting tank and a reverse osmosis raw water tank communicated with the hollow fiber nanofiltration membrane assembly; the reverse osmosis raw water tank is respectively communicated with the reverse osmosis concentrated water collecting tank and the reverse osmosis water producing tank. The method has the advantages of high recovery rate and low operation cost.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial desalination, and particularly to a device and a method for preparing industrial desalted water. Background Art

[0002] In recent years, with the increasing shortage of water resources, the decreasing annual available amount of surface water, and the increasing annual sewage discharge cost of enterprises, more and more enterprises use industrial sewage instead of surface water as the raw water for industrial desalted water preparation. At the same time, the sewage reuse project has also been widely implemented in China. However, the salt content in industrial sewage is often relatively high, which is difficult to treat and cannot meet the requirements of industrial production and reclaimed water quality. Especially in the chemical industry, in recent years, the application scope and application standards of industrial desalted water in the chemical industry have been continuously expanding and increasing. High-quality desalted water can not only improve the use efficiency but also play a certain role in protecting equipment. Therefore, the development of its preparation process technology has also become a key concern in the chemical industry, which also forces the continuous development and improvement of desalted water treatment technology.

[0003] The desalted water treatment process generally refers to the process of removing strong conductive substances in water and, to a certain extent, removing weak electrolytes such as carbon dioxide in water, which can also be called pure water treatment process or deep desalted water. Currently, the relatively mature desalted water treatment processes on the market include electrodialysis method, ion exchange method, reverse osmosis method, EDI method, etc.

[0004] Ion exchange process: The traditional desalted water treatment process is mainly the full ion exchange process of pretreatment + cation bed + anion bed + mixed bed. The conventional pretreatment methods for surface water are mostly multi-media filtration + activated carbon filtration. The full ion exchange can make the quality of the effluent stable and meet the standards. Experiments have proved that the traditional treatment process is relatively mature, but it also has certain limitations. Due to the limitations of pretreatment and ion exchange processes, the traditional process has defects such as occupying a large amount of space by equipment, complex operation, frequent maintenance, unstable effluent quality, etc. And during the treatment process, flocculants need to be added, consuming a large amount of acid and alkali, which will also cause certain pollution to the environment.

[0005] Full membrane method desalted water process: The full membrane method desalted water process is an organic combination of different membrane processes such as ultrafiltration, microfiltration, reverse osmosis, and EDI to achieve efficient removal of pollutants and deep desalination. Its characteristics are high investment, modular combination, less land occupation, convenient operation, replacing ion exchange desalination with reverse osmosis to remove dissolved salts in water; replacing mixed bed deep desalination with EDI, and using electricity instead of acid and alkali to regenerate the resin, which can avoid acid and alkali, but has high power consumption.

[0006] Dual-membrane method + IX desalinated water preparation process: The dual-membrane method + IX desalinated water preparation process combines the ultrafiltration / reverse osmosis dual-membrane method and the traditional mixed-bed process, and is a new process designed according to on-site conditions. Its characteristics are moderate investment, convenient operation, and moderate operating costs.

[0007] Currently, the dual-membrane method with post-treatment is the main desalination treatment process in the market. However, in the current process, the water production recovery rate is between 60% and 75%, resulting in a large amount of water resource loss. Summary of the Invention

[0008] In order to overcome the deficiencies of the background technology, the present invention provides a device for preparing industrial desalinated water with a high recovery rate and low operating cost.

[0009] The technical solution adopted by the present invention: A device for preparing industrial desalinated water includes a raw water tank, a heat exchanger, a self-cleaning filter, an ultrafiltration module, an ultrafiltration water tank, a reverse osmosis module, a reverse osmosis product water tank, a mixed bed, and a desalinated water tank connected in sequence. A concentrated water reuse module is provided between the reverse osmosis module and the reverse osmosis product water tank. The concentrated water reuse module includes a reverse osmosis concentrated water collection tank with a reverse osmosis membrane, a hollow fiber nanofiltration membrane module connected to the reverse osmosis concentrated water collection tank, and a reverse osmosis raw water tank connected to the hollow fiber nanofiltration membrane module. The reverse osmosis raw water tank is respectively connected to the reverse osmosis concentrated water collection tank and the reverse osmosis product water tank.

[0010] A nanofiltration raw water pump for discharging reverse osmosis concentrated water into the hollow fiber nanofiltration membrane module is provided in the reverse osmosis concentrated water collection tank.

[0011] The reverse osmosis raw water tank and the hollow fiber nanofiltration membrane module are both provided with mud discharge ports.

[0012] It further includes a backwash water reuse module. The backwash water reuse module includes a backwash water collection pool and a high-efficiency sand filter. The backwash water collection pool is respectively connected to the self-cleaning filter, the ultrafiltration module, and the high-efficiency sand filter. The high-efficiency sand filter is connected to the raw water tank.

[0013] The beneficial effects of the present invention are: This technical solution performs secondary treatment on the reverse osmosis concentrated water of the desalinated water process through the combination of a hollow fiber nanofiltration membrane module and a reverse osmosis membrane, improving the recovery rate of the desalinated water process from 60% - 75% to over 92%. In addition, it can reduce the chemical dosage in the water treatment process and reduce the wastewater discharge. The operating cost is much lower than the traditional process, and it has good energy-saving effects. Brief Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of the device for preparing industrial desalinated water according to the embodiment of the present invention.

[0015] Figure 2Process flow diagram of the device for preparing industrial demineralized water.

[0016] Figure 3 Actual case data of the device for preparing industrial demineralized water. Embodiment

[0017] The following further describes the embodiments of the present invention with reference to the accompanying drawings: As shown in the figure, a device for preparing industrial demineralized water includes a raw water tank 1, a heat exchanger 2, a self-cleaning filter 3, an ultrafiltration module 4, an ultrafiltration water tank 5, a reverse osmosis module 6, a reverse osmosis product water tank 7, a mixed bed 8, and a demineralized water tank 9 that are connected in sequence. A concentrated water reuse module is provided between the reverse osmosis module 6 and the reverse osmosis product water tank 7. The concentrated water reuse module includes a reverse osmosis concentrated water collection tank 10 with a reverse osmosis membrane, a hollow fiber nanofiltration membrane module 11 connected to the reverse osmosis concentrated water collection tank 10, and a reverse osmosis raw water tank 12 connected to the hollow fiber nanofiltration membrane module 11. The reverse osmosis raw water tank 12 is respectively connected to the reverse osmosis concentrated water collection tank 10 and the reverse osmosis product water tank 7; it also includes a backwash water reuse module. The backwash water reuse module includes a backwash water collection tank 13 and a high-efficiency sand filter 14. The backwash water collection tank 13 is respectively connected to the self-cleaning filter 3, the ultrafiltration module 4, and the high-efficiency sand filter 14, and the high-efficiency sand filter 14 is connected to the raw water tank 1; in this technical solution, the reverse osmosis concentrated water of the demineralized water process is secondary-treated by combining a hollow fiber nanofiltration membrane module and a reverse osmosis membrane, improving the recovery rate of the demineralized water process, increasing the recovery rate from 60 - 75% to over 92%; in addition, it can reduce the chemical dosage in the water treatment process and reduce the wastewater discharge; the operating cost is much lower than the traditional process and has a good energy-saving effect.

[0018] The hollow fiber nanofiltration membrane can remove most divalent and high-valent salts in the reverse osmosis concentrated water, and at the same time remove most of the organic pollutants introduced during the removal process, playing a role in salt separation, effectively realizing the separation between monovalent and high-valent salts. Moreover, the operating pressure of the hollow fiber nanofiltration membrane is 0.2 - 0.4 MPa, with a low operating pressure, a small floor area, and easy operation; the reverse osmosis membrane further removes organic pollutants and monovalent salts, thus completing the reuse of the system's reverse osmosis concentrated water; the present invention can reduce the chemical dosage in the water treatment process, reduce the wastewater discharge, and increase the recovery rate of the system; the operating cost is much lower than the traditional process and has a good energy-saving effect.

[0019] A nanofiltration raw water pump for discharging the reverse osmosis concentrated water into the hollow fiber nanofiltration membrane module 11 is provided in the reverse osmosis concentrated water collection tank 10 for low-pressure nanofiltration operation.

[0020] Both the reverse osmosis raw water tank 12 and the hollow fiber nanofiltration membrane module 11 are provided with sludge discharge outlets.

[0021] The reverse osmosis concentrated water enters the reverse osmosis concentrated water collection tank; it enters the hollow fiber nanofiltration system through the nanofiltration raw water pump for low-pressure nanofiltration operation; the water produced by the hollow fiber nanofiltration system enters the reverse osmosis raw water tank 12, and the concentrated water returns to the reverse osmosis concentrated water collection tank; the reverse osmosis produced water enters the reverse osmosis product water tank, and the reverse osmosis concentrated water is divided into two parts, one part returns to the reverse osmosis concentrated water collection tank, and the other part is discharged outward; its treatment effect is proved by actual implementation cases. After the application of this device, the recovery rate of the desalted water treatment system has increased by 15 - 18%, and the water recovery rate of the overall system is stabilized above 92%.

[0022] A method for preparing industrial desalted water includes at least the following steps: S1. Raw water enters the reverse osmosis concentrated water collection tank 10 from the raw water tank 1 via the heat exchanger 2, self-cleaning filter 3, ultrafiltration module 4, ultrafiltration water tank 5, and reverse osmosis module 6; S2. The nanofiltration raw water pump works to drain the reverse osmosis concentrated water into the hollow fiber nanofiltration membrane module; S3. The hollow fiber nanofiltration membrane module 11 performs low-pressure nanofiltration operation on the reverse osmosis concentrated water. The water produced after the treatment by the hollow fiber nanofiltration membrane module 11 enters the reverse osmosis raw water tank 12 through the water production channel, and enters the desalted water tank 9 via the reverse osmosis product water tank 7 and mixed bed 8; The concentrated water after the treatment by the hollow fiber nanofiltration membrane module 11 is divided into two parts. One part returns to the reverse osmosis concentrated water collection tank 10 through the return water channel, and the other part is discharged outward.

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In addition, in the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0025] Notice to all technical personnel: Although the present invention has been described according to the above specific embodiments, the inventive concept of the present invention is not limited to this invention only. Any modification that utilizes the inventive concept of the present invention will be included within the scope of protection of the patent right of this patent.

Claims

1. An apparatus for preparing industrial desalted water, characterized in that: It includes a raw water tank (1), a heat exchanger (2), a self-cleaning filter (3), an ultrafiltration module (4), an ultrafiltration water tank (5), a reverse osmosis module (6), a reverse osmosis product water tank (7), a mixed bed (8), and a demineralized water tank (9) that are connected in sequence. A concentrated water reuse module is provided between the reverse osmosis module (6) and the reverse osmosis product water tank (7). The concentrated water reuse module includes a reverse osmosis concentrated water collection tank (10), a hollow fiber nanofiltration membrane module (11), and a reverse osmosis raw water tank (12). The reverse osmosis concentrated water collection tank (10) includes a reverse osmosis membrane. The water inlet of the hollow fiber nanofiltration membrane module (11) is connected to the reverse osmosis concentrated water collection tank (10), the product water outlet is connected to the reverse osmosis raw water tank (12) through a product water channel, and the concentrated water outlet is connected to the reverse osmosis concentrated water collection tank (10) through a return water channel. The reverse osmosis raw water tank (12) is respectively connected to the reverse osmosis concentrated water collection tank (10) and the reverse osmosis product water tank (7). A nanofiltration raw water pump is provided in the reverse osmosis concentrated water collection tank (10), and the nanofiltration raw water pump is used to discharge the reverse osmosis concentrated water into the hollow fiber nanofiltration membrane module.

2. The device for preparing industrial desalted water according to claim 1, wherein: Both the reverse osmosis raw water tank (12) and the hollow fiber nanofiltration membrane module (11) are provided with sludge discharge ports.

3. The device for preparing industrial desalted water according to claim 1, wherein: It further includes a backwash water reuse module. The backwash water reuse module includes a backwash water collection pool (13) and a high-efficiency sand filter (14). The backwash water collection pool (13) is respectively connected to the self-cleaning filter (3), the ultrafiltration module (4), and the high-efficiency sand filter (14), and the high-efficiency sand filter (14) is connected to the raw water tank (1).

4. The device for preparing industrial desalted water according to claim 1, characterized in that: A drain port is provided on the reverse osmosis concentrated water collection tank.

5. A method for preparing industrial desalted water, characterized in that: Use the device according to any one of claims 1-3; At least include the following steps: S1. Raw water enters the reverse osmosis concentrated water collection tank (10) from the raw water tank (1) via the heat exchanger (2), the self-cleaning filter (3), the ultrafiltration module (4), the ultrafiltration water tank (5), and the reverse osmosis module (6). S2. The nanofiltration raw water pump works to discharge the reverse osmosis concentrated water into the hollow fiber nanofiltration membrane module. S3. The hollow fiber nanofiltration membrane module (11) performs low-pressure nanofiltration operation on the reverse osmosis concentrated water. The product water after being treated by the hollow fiber nanofiltration membrane module (11) enters the reverse osmosis raw water tank (12) via the product water channel, and enters the demineralized water tank (9) via the reverse osmosis product water tank (7) and the mixed bed (8). The concentrated water after being treated by the hollow fiber nanofiltration membrane module (11) is divided into two parts. One part returns to the reverse osmosis concentrated water collection tank (10) via the return water channel, and the other part is discharged outward.

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