CN110304690A - A kind of reverse osmosis treatment method containing brine and reverse osmosis system - Google Patents

Abstract

The invention relates to the field of water treatment, in particular to a reverse osmosis treatment method containing brine and a reverse osmosis system. The reverse osmosis system includes: a first reverse osmosis unit, a second reverse osmosis unit, a third reverse osmosis unit, a first high-pressure pump, a second high-pressure pump and a first energy recovery unit. Wherein, the apparent salt rejection rate of the second reverse osmosis unit is smaller than the apparent salt rejection rate of the first reverse osmosis unit. Through the ingenious combination of multiple reverse osmosis units, the reverse osmosis system of the present invention can not only effectively break through the concentration limit of the traditional reverse osmosis system, but also ensure the water quality of the system produced water, effectively reduce the use of high-pressure pumps in the combined system, and simplify the system Design, and reduce the investment cost of the combined system. The present invention also adds an energy recovery unit to the combined reverse osmosis system to recover and convert the unused residual energy in the system, thereby further reducing the energy consumption of the system.

Description

A kind of reverse osmosis treatment method containing brine and reverse osmosis system

technical field

The invention relates to the field of water treatment, in particular to a reverse osmosis treatment method containing brine and a reverse osmosis system.

Background technique

With the continuous improvement of environmental protection requirements, contradictions such as insufficient water resources and limited environmental capacity have become increasingly prominent. In the production processes of petrochemical, coal chemical, electric power, steel and seawater desalination, a large amount of salty wastewater will be produced. In order to reduce the amount of external drainage and improve the efficiency of water use, currently salty wastewater is generally treated by reverse osmosis-based membrane method and then recycled, which improves the efficiency of water use to a certain extent.

However, due to the existence of osmotic pressure and the limitation of actual operating pressure, the existing conventional reverse osmosis membrane module and the reverse osmosis system formed by the conventional reverse osmosis membrane module can only concentrate brine to 50,000mg/L to 70,000mg/L , which seriously limits the further improvement of the water recovery rate of the reverse osmosis system, and thus produces a large amount of concentrated brine. This puts huge pressure on investment and energy consumption for subsequent treatment, especially subsequent evaporation, crystallization and other process treatments when zero liquid discharge is required. Although the ultra-high pressure reverse osmosis membrane module and the reverse osmosis system formed by the conventional reverse osmosis membrane module can break through the concentration limit, their cost and operation cost are high and there are certain safety hazards.

Contents of the invention

The object of the present invention is to provide a novel reverse osmosis treatment method containing brine and a reverse osmosis system. The reverse osmosis system of the present invention can break through the concentration limit of the reverse osmosis system without significantly increasing operating pressure and operating costs. Significantly reduce the final discharge of concentrated brine in the system.

In order to achieve the above object, the present invention provides a reverse osmosis system, which comprises: a first reverse osmosis unit, a second reverse osmosis unit, a third reverse osmosis unit, a first high pressure pump, a second high pressure pump and The first energy recovery unit; the first reverse osmosis unit includes a reverse osmosis inlet A1, a reverse osmosis concentrated water outlet B1 and a reverse osmosis product water outlet C1, and the second reverse osmosis unit includes a reverse osmosis inlet A2, a reverse osmosis concentrated water Outlet B2 and reverse osmosis water product outlet C2, the third reverse osmosis unit includes reverse osmosis inlet A3, reverse osmosis concentrated water outlet B3 and reverse osmosis water product outlet C3; the first energy recovery unit includes high pressure inlet D1, drain Pressure outlet D2, low pressure inlet E1 and booster outlet E2;

Wherein, the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit communicates with the reverse osmosis inlet A2 of the second reverse osmosis unit, so that the concentrated water from the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit Water enters into the second reverse osmosis unit for treatment;

The reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit communicates with the high-pressure inlet D1 of the first energy recovery unit, so that the concentrated water from the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit passes through the The pressure relief of the first energy recovery unit;

The reverse osmosis produced water outlet C1 of the first reverse osmosis unit communicates with the inlet of the second high-pressure pump, and the outlet of the second high-pressure pump communicates with the reverse osmosis inlet A3 of the third reverse osmosis unit, so that the The product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit is pressurized and enters the third reverse osmosis unit for treatment;

The reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit and the reverse osmosis product water outlet C2 of the second reverse osmosis unit are connected with the raw water pipeline, so that the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit The concentrated water coming out and the product water coming out of the reverse osmosis product water outlet C2 of the second reverse osmosis unit merge with the raw water;

The raw water pipeline communicates with the inlet of the first high-pressure pump and the low-pressure inlet E1 of the first energy recovery unit respectively, and the pressurized outlet E2 of the first energy recovery unit and the outlet of the first high-pressure pump are both connected to the first high-pressure pump. The reverse osmosis inlet A1 of the first reverse osmosis unit is connected, so that part of the brine in the raw water pipeline enters the first energy recovery unit, and the concentrated water from the reverse osmosis concentrated water outlet B2 is discharged in the first energy recovery unit. The energy generated by the pressure will be pressurized, while another part of the brine in the raw water pipeline will be pressurized by the first high-pressure pump, and the brine after the pressurization of the first energy recovery unit and the pressurized first high-pressure pump will be sent to the The treatment is carried out in the first reverse osmosis unit described above.

The second aspect of the present invention provides a reverse osmosis treatment method containing brine, the method is carried out in a reverse osmosis system, and the reverse osmosis system includes: a first reverse osmosis unit, a second reverse osmosis unit, a third reverse osmosis unit, The first high-pressure pump, the second high-pressure pump and the first energy recovery unit; the first reverse osmosis unit includes a reverse osmosis inlet A1, a reverse osmosis concentrated water outlet B1 and a reverse osmosis product water outlet C1, and the second reverse osmosis unit Including reverse osmosis inlet A2, reverse osmosis concentrated water outlet B2 and reverse osmosis product water outlet C2, the third reverse osmosis unit includes reverse osmosis inlet A3, reverse osmosis concentrated water outlet B3 and reverse osmosis product water outlet C3; An energy recovery unit includes a high pressure inlet D1, a pressure relief outlet D2, a low pressure inlet E1 and a booster outlet E2;

The method includes: sending the brine to be treated as raw water together with concentrated water from the third reverse osmosis unit and product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit to the first high-pressure pump to increase pressure; and part of the brine after the raw water is optionally combined with the concentrated water from the third reverse osmosis unit and/or the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit is sent to the first reverse osmosis unit. The low-pressure inlet E1 of the energy recovery unit is pressurized, and then the brine from the boost outlet E2 of the first energy recovery unit is sent to the first reverse osmosis unit together with the brine pressurized by the first high-pressure pump for treatment ;

The concentrated water from the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit is sent to the second reverse osmosis unit for treatment, and the concentrated water from the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit is sent to the high-pressure inlet D1 of the first energy recovery unit to perform pressure relief in the first energy recovery unit, and then come out from the pressure relief outlet D2 of the first energy recovery unit and be discharged as system concentrated water;

The product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit is boosted by the second high-pressure pump and sent to the third reverse osmosis unit for treatment, and the reverse osmosis product from the third reverse osmosis unit The output from water outlet C3 is discharged as system produced water.

Through the ingenious combination of multiple reverse osmosis units, the reverse osmosis system of the present invention can not only effectively break through the concentration limit of the traditional reverse osmosis system under the operating pressure of the traditional reverse osmosis system, but also ensure the water quality of the system produced water, and at the same time effectively reduce the combined system The use of medium and high pressure pumps simplifies the system design and reduces the investment and operating costs of the combined system. The present invention also adds an energy recovery unit to the combined reverse osmosis system to recover and convert the unused residual energy in the system, thereby further reducing the energy consumption of the system.

Description of drawings

Fig. 1 is a schematic diagram of a reverse osmosis system according to a preferred embodiment of the present invention.

Fig. 2 is a schematic diagram of a reverse osmosis system according to another preferred embodiment of the present invention.

Fig. 3 is a schematic diagram of a reverse osmosis system according to yet another preferred embodiment of the present invention.

Fig. 4 is a schematic diagram of a reverse osmosis system according to another preferred embodiment of the present invention.

Figure 5 is a schematic diagram of a conventional series reverse osmosis unit.

Figure 6 is a schematic diagram of a conventional series reverse osmosis unit.

Explanation of reference signs

1—the first reverse osmosis unit; 2—the second reverse osmosis unit; 3—the third reverse osmosis unit;

4——the first high-pressure pump; 5——the second high-pressure pump;

6——the first pump; 7——the second pump;

8—the first energy recovery unit; 9—the second energy recovery unit.

Detailed ways

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

One aspect of the present invention provides a reverse osmosis system, the reverse osmosis system includes: a first reverse osmosis unit 1, a second reverse osmosis unit 2, a third reverse osmosis unit 3, a first high pressure pump 4, a second high pressure pump 5 and The first energy recovery unit 8; the first reverse osmosis unit 1 includes a reverse osmosis inlet A1, a reverse osmosis concentrated water outlet B1 and a reverse osmosis product water outlet C1, and the second reverse osmosis unit 2 includes a reverse osmosis inlet A2, reverse osmosis Permeate concentrated water outlet B2 and reverse osmosis product water outlet C2, the third reverse osmosis unit 3 includes reverse osmosis inlet A3, reverse osmosis concentrated water outlet B3 and reverse osmosis product water outlet C3; the first energy recovery unit 8 includes High pressure inlet D1, pressure relief outlet D2, low pressure inlet E1 and booster outlet E2;

Wherein, the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1 communicates with the reverse osmosis inlet A2 of the second reverse osmosis unit 2, so that the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1 The concentrated water coming out enters the second reverse osmosis unit 2 for processing;

The reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit 2 communicates with the high-pressure inlet D1 of the first energy recovery unit 8, so that the concentrated reverse osmosis water outlet B2 of the second reverse osmosis unit 2 comes out The water is depressurized through the first energy recovery unit 8;

The reverse osmosis produced water outlet C1 of the first reverse osmosis unit 1 communicates with the inlet of the second high-pressure pump 5, and the outlet of the second high-pressure pump 5 communicates with the reverse osmosis inlet A3 of the third reverse osmosis unit 3, so that the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 enters the third reverse osmosis unit 3 for treatment after being pressurized;

The reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 and the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 are connected with the raw water pipeline, so that the reverse osmosis concentrated water of the third reverse osmosis unit 3 The concentrated water from the water outlet B3 and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 merge with the raw water;

The raw water pipeline communicates with the inlet of the first high-pressure pump 4 and the low-pressure inlet E1 of the first energy recovery unit 8, and the booster outlet E2 of the first energy recovery unit 8 communicates with the outlet of the first high-pressure pump 4. The outlets are all communicated with the reverse osmosis inlet A1 of the first reverse osmosis unit 1, so that part of the brine in the raw water pipeline enters the first energy recovery unit 8 and uses the concentrated water from the reverse osmosis concentrated water outlet B2 in the first reverse osmosis unit. The energy generated by depressurization in an energy recovery unit 8 is pressurized, while another part of brine in the raw water pipeline is pressurized by the first high-pressure pump 4, and after the first energy recovery unit 8 is pressurized and the first high-pressure The brine pressurized by the pump 4 is sent to the first reverse osmosis unit 1 for treatment.

The second aspect of the present invention provides a reverse osmosis treatment method containing brine, the method is carried out in a reverse osmosis system, and the reverse osmosis system includes: a first reverse osmosis unit 1, a second reverse osmosis unit 2, a third reverse osmosis unit Unit 3, a first high-pressure pump 4, a second high-pressure pump 5, and a first energy recovery unit 8; the first reverse osmosis unit 1 includes a reverse osmosis inlet A1, a reverse osmosis concentrated water outlet B1, and a reverse osmosis product water outlet C1, The second reverse osmosis unit 2 includes a reverse osmosis inlet A2, a reverse osmosis concentrated water outlet B2, and a reverse osmosis product water outlet C2, and the third reverse osmosis unit 3 includes a reverse osmosis inlet A3, a reverse osmosis concentrated water outlet B3 and a reverse osmosis outlet. Permeate water outlet C3; the first energy recovery unit 8 includes a high pressure inlet D1, a pressure relief outlet D2, a low pressure inlet E1 and a booster outlet E2;

The method includes: sending the brine to be treated as raw water together with concentrated water from the third reverse osmosis unit 3 and product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 to the first high-pressure pump 4 to pressurize; and part of the salt water after the raw water is optionally combined with the concentrated water from the third reverse osmosis unit 3 and/or the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 is sent to the low-pressure inlet E1 of the first energy recovery unit 8 to pressurize, and then send the brine from the boost outlet E2 of the first energy recovery unit 8 together with the brine pressurized by the first high-pressure pump 4 to Process in the first reverse osmosis unit 1;

The concentrated water from the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1 is sent to the second reverse osmosis unit 2 for treatment, and the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit 2 is discharged The concentrated water is sent to the high-pressure inlet D1 of the first energy recovery unit 8 for pressure relief in the first energy recovery unit 8, and then comes out from the pressure relief outlet D2 of the first energy recovery unit 8 and used as the system concentrated water. water discharge;

The product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 is pressurized by the second high-pressure pump 5 and sent to the third reverse osmosis unit 3 for treatment, and the water from the third reverse osmosis unit 3 The produced reverse osmosis product water outlet C3 is discharged as system product water.

The above methods and systems will be described in nested form below, but it should be understood that the following descriptions are applicable to the two subjects, and they can exist independently of each other or in conjunction with each other, which is within the scope of the present invention .

According to the present invention, the brine to be treated as the raw water can be brine with various salt concentrations conventional in the art. In particular, the reverse osmosis system of the present invention can further concentrate high-content brine. For example, the salt content of the brine is 30,000-90,000 mg/L to obtain concentrated brine with a concentration of 100,000-200,000 mg/L, and the resulting system product water will have a lower salt concentration, for example, 2,000 mg/L L or less, preferably less than 1,000 mg/L; in particular, reverse osmosis treatment can be performed on brine with a salt content of 50,000-70,000 mg/L to obtain concentrated brine with a concentration of 120,000-180,000 mg/L, and the resulting system The product water will have a lower salt concentration, for example below 4,000 mg/L, preferably below 2,000 mg/L. However, the traditional reverse osmosis system can only concentrate brine to a concentration of 50,000-70,000mg/L brine, and for brine with a high concentration (such as 50,000-70,000mg/L), the usual operating pressure Concentration cannot be achieved at all. Wherein, usually the salt water refers to NaCl salt water, and the above-mentioned concentration is also calculated by NaCl.

According to the present invention, as shown in Figure 1, the reverse osmosis system of the present invention comprises at least 3 reverse osmosis units and at least one energy recovery unit, through the ingenious combination of these 3 reverse osmosis units and at least one energy recovery unit, can be in Using 2 high-pressure pumps to increase the concentration limit of the entire system.

Wherein, the first reverse osmosis unit 1, the second reverse osmosis unit 2 and the third reverse osmosis unit 3 can adopt the reverse osmosis unit assembled by the conventional reverse osmosis membrane in this field, but in order to improve the cooperation between each reverse osmosis unit , preferably, the apparent rejection rate of the first reverse osmosis unit 1 is 20-80%, the apparent rejection rate of the second reverse osmosis unit 2 is 20-80%, and the third reverse osmosis unit 3 The apparent rejection rate is above 90%. More preferably, the apparent rejection rate of the first reverse osmosis unit 1 is 40-70%, the apparent rejection rate of the second reverse osmosis unit 2 is 25-45%, and the third reverse osmosis unit 3 The apparent rejection rate is more than 95% (more preferably more than 99%). In the present invention, the term "apparent rejection rate" can be considered to refer to the measured rejection rate, which is a general term in the field of membrane separation, and the present invention has no special limitation on it. It should be understood that, usually, the concentrated water outlet of the reverse osmosis unit is provided with a pressure holding valve so as to maintain the pressure in the reverse osmosis unit, so that the concentrated water coming out of the pressure holding valve does not carry pressure. However, as described below, when the concentrated water from the reverse osmosis unit needs to be depressurized through the energy recovery unit, the concentrated water from the energy recovery unit in the reverse osmosis unit can be directly sent to the energy recovery unit, although the following content is for The pressure holding valve is not described in detail, but it is a conventional arrangement in the field, and the present invention will not describe it too much.

According to the present invention, the brine to be treated is sent to the first high-pressure pump together with the concentrated water from the third reverse osmosis unit 3 and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 as raw water 4 to supercharge. Wherein, the concentrated water from the reverse osmosis concentrated water outlet B3 from the third reverse osmosis unit 3 and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 can be merged with the raw water at the same time, or can be Combined with raw water respectively.

Wherein, the first high-pressure pump 4 will make a major contribution to the operating pressure of the first reverse osmosis unit 1 and the operating pressure of the second reverse osmosis unit 2 . For this reason, the first high-pressure pump 4 can adopt any conventional high-pressure pump in the field that can obtain the above-mentioned boosting effect, for example, the lift of the first high-pressure pump 4 is 100-700 m.

According to the present invention, for the reverse osmosis system of the present invention, in order to realize the above process, the concentrated water pipeline from the third reverse osmosis unit 3 and the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 can be discharged The product water pipeline is connected with the raw water pipeline at the same position of the raw water pipeline, or the concentrated water pipeline from the third reverse osmosis unit 3 is connected with the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 The pipeline is connected with the raw water pipeline at different positions of the raw water pipeline, and the specific pipeline settings can refer to the drawings. Of course, an intermediate water tank may also be provided so that the raw water is mixed with the concentrated water from the third reverse osmosis unit 3 and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2, and then sent to Subsequent processing.

After the raw water, the concentrated water from the third reverse osmosis unit 3 and the mixed brine from the second reverse osmosis unit 2 are pressurized by the first high-pressure pump 4, the obtained pressurized brine is mixed with the first The brine from the pressurized outlet E2 of the energy recovery unit 8 is sent to the first reverse osmosis unit 1 together for treatment.

Wherein, the pressure of the brine entering from the reverse osmosis inlet A1 of the first reverse osmosis unit 1 may be, for example, 4-7 MPa. This pressure is substantially contributed by the first high pressure pump 4 and the first energy recovery unit 8 .

According to the present invention, the brine coming out of the pressurization outlet E2 of the first energy recovery unit 8 is actually part of the brine that should have been sent to the first high-pressure pump 4 for pressurization and sent to the first energy recovery unit 8 , which enters from the low pressure inlet E1 and is pressurized by the energy provided by the pressure relief part of the first energy recovery unit 8 . The energy provided by the pressure relief part is also provided by the system itself, that is, the pressurized concentrated water from the second reverse osmosis unit 2 enters directly from the high-pressure inlet D1 of the first energy recovery unit 8, and the pressure relief process generates energy. This energy provides the pressurized part to pressurize the brine, and the concentrated water after pressure relief is discharged from the system as system concentrated water.

For this reason, for the reverse osmosis system of the present invention, the diversion point that diverts part of the brine from the raw water pipeline to the first energy recovery unit 8 can be set before the brine confluence point of other pipelines, or it can be set before the brine confluence point of the other pipelines. Between the point where the concentrated water of the third reverse osmosis unit 3 joins the raw water pipeline and the point where the product water of the second reverse osmosis unit 2 joins the raw water pipeline (including two cases, that is, the third reverse osmosis unit The point where the concentrated water of 3 and the raw water pipeline meet is before the point where the product water of the second reverse osmosis unit 2 meets the raw water pipeline, and the point where the raw water pipeline meets the product water of the second reverse osmosis unit 2 The point where the point where the raw water line merges with the raw water line is before the point where the concentrated water of the third reverse osmosis unit 3 joins the raw water line); The point is set after the point where the concentrated water of the third reverse osmosis unit 3 joins the raw water pipeline and the point where the product water of the second reverse osmosis unit 2 joins the raw water pipeline, and is arranged before the first high pressure pump 4 On the raw water pipeline.

According to the present invention, the brine sent to the first energy recovery unit 8 for pressurization may be part of the raw water, or part of the brine mixed with the concentrated water from the third reverse osmosis unit 3, or the mixture of raw water and Part of the brine obtained by mixing the product water from the second reverse osmosis unit 2 may also be part of the brine obtained by mixing the raw water with the concentrated water from the third reverse osmosis unit 3 and the product water from the second reverse osmosis unit 2 .

In a preferred embodiment of the present invention, only part of the brine after the raw water and concentrated water from the third reverse osmosis unit 3 are combined is sent to the low-pressure inlet E1 of the first energy recovery unit 8 for pressurization. For this reason, preferably, part of the brine and another part of the raw water that are sent to the low-pressure inlet E1 of the first energy recovery unit 8 from the raw water and the concentrated water from the third reverse osmosis unit 3 are combined with the third reverse osmosis unit The volume flow ratio of the mixed brine sent to the high-pressure pump 4 after the concentrated water from 3 is combined and mixed with the product water of the second reverse osmosis unit is 0.05-1:1, preferably 0.1-0.5:1.

In this embodiment, the diversion point for diverting part of the brine from the raw water pipeline to the first energy recovery unit 8 is set at the point where the concentrated water of the third reverse osmosis unit 3 joins the raw water pipeline and the second Between the point where the produced water of the second reverse osmosis unit 2 and the raw water pipeline meet, and the point where the concentrated water of the third reverse osmosis unit 3 and the raw water pipeline meet is set between the produced water and the raw water of the second reverse osmosis unit 2 Before the point where the lines meet.

In another preferred embodiment of the present invention, after the raw water is combined with the concentrated water from the third reverse osmosis unit 3 and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 Part of the brine is sent to the low-pressure inlet E1 of the first energy recovery unit 8 for pressurization. For this reason, preferably, the raw water sent to the low-pressure inlet E1 of the first energy recovery unit 8 and the concentrated water from the third reverse osmosis unit 3 and the reverse osmosis product water outlet of the second reverse osmosis unit 2 The volume flow ratio of part of the brine after the confluence of the product water from C2 to another part of the confluence brine is 0.05-1:1, preferably 0.1-0.5:1. In this embodiment, the branch point for diverting part of the brine from the raw water pipeline to the first energy recovery unit 8 is set at the point where the concentrated water of the third reverse osmosis unit 3 joins the raw water pipeline and the second After the point where the produced water of the second reverse osmosis unit 2 meets the raw water pipeline, it is arranged on the raw water pipeline before the first high pressure pump 4 .

According to the present invention, preferably, the volume flow ratio of the brine entering from the high-pressure inlet D1 of the first energy recovery unit 8 and the brine entering from the low-pressure inlet E1 of the first energy recovery unit 8 is 1:0.7- 1.3, preferably 1:0.9-1.1.

According to the present invention, the first energy recovery unit 8 may be an energy recovery device having the above performance, for example, it may be the iSave series of Danfoss Company, or the PX series of ERI Company. The first energy recovery unit 8 can be equal pressure type or differential pressure type, and it can also have a self-increasing function, especially when the first energy recovery unit 8 with a self-increasing function is adopted, then the following Said first pump 6 just can not adopt.

According to the present invention, the reverse osmosis system may further include a first pump 6, whereby the pressurized outlet E2 of the first energy recovery unit 8 communicates with the inlet of the first pump 6, and the outlet of the first pump 6 communicates with the inlet of the first pump 6. The outlets of the first high-pressure pump 4 are all in communication with the reverse osmosis inlet A1 of the first reverse osmosis unit 1 . Then the method of the present invention may include: sending the brine from the pressurized outlet E2 of the first energy recovery unit 8 to the first pump 6, and combining the brine from the outlet of the first pump 6 with the first high pressure The brine pressurized by the pump 4 is sent together to the first reverse osmosis unit 1 for treatment.

Wherein, the first pump 6 may be a booster pump. The booster pump can be a conventional booster pump in the field, for example, its withstand pressure is 3-10MPa, and its head is 20-100m.

According to the present invention, preferably, the brine entering from the reverse osmosis inlet A1 of the first reverse osmosis unit 1 has a pressure of 4-7 MPa.

According to the present invention, the brine after the pressurization of the first high-pressure pump 4 is merged with the brine from the pressurized outlet E2 of the first energy recovery unit 8 and then sent to the first reverse osmosis unit 1 for treatment, from the first reverse osmosis unit The reverse osmosis inlet A1 of 1 enters, the obtained concentrated water is discharged from the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1, and the product water is discharged from the reverse osmosis product water outlet C1.

Wherein, the concentrated water discharged from the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1 will be sent to the second reverse osmosis unit 2 for treatment, and can also be processed in the first reverse osmosis unit 1 and the second reverse osmosis unit A booster pump is arranged between 2 to send the concentrated water discharged from the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1 to the second reverse osmosis unit 2 for treatment after a certain boost. As mentioned above, the concentrated water from the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit 2 is sent to the high-pressure inlet D1 of the first energy recovery unit 8 so that in the first energy recovery unit 8 The pressure is released, and then it comes out from the pressure relief outlet D2 of the first energy recovery unit 8 and is discharged as system concentrated water. The product water from the second reverse osmosis unit 2 is circulated to the raw water pipeline to be pressurized and sent to the first reverse osmosis unit 1 for circulation treatment.

According to the present invention, preferably, the brine entering from the reverse osmosis inlet A2 of the second reverse osmosis unit 2 has a pressure of 4-7 MPa.

According to the present invention, all the produced water from the reverse osmosis produced water outlet C1 of the first reverse osmosis unit 1 can be directly pressurized by the second high pressure pump 5 and sent to the third reverse osmosis unit 3 for treatment, while The product water from the reverse osmosis product water outlet C3 of the third reverse osmosis unit 3 is used as the system product water discharge system, and the concentrated water from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 is directly reused to the raw water pipeline Mixed with raw water to continue recycling to the first reverse osmosis unit 1 for treatment.

In view of the above situation, the reverse osmosis system of the present invention, then as shown in Figure 1 and Figure 2, the reverse osmosis produced water outlet C1 of the first reverse osmosis unit 1 and the second high pressure pump 5 (it can also be provided with a feed pump), the outlet of the second high pressure pump 5 is connected with the reverse osmosis inlet A3 of the third reverse osmosis unit 3, and the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 is directly connected To the raw water pipeline, that is, the product water pipeline from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 is no longer divided, and the concentrated water pipeline from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 Also no longer through other devices.

Wherein, the second high-pressure pump 5 will make a major contribution to the operating pressure of the third reverse osmosis unit 3 . For this reason, the second high-pressure pump 5 can adopt any high-pressure pump conventional in the art that can obtain the above-mentioned boosting effect, for example, the head of the second high-pressure pump 5 is 400-700m.

However, preferably, the reverse osmosis system further includes a second energy recovery unit 9, and the second energy recovery unit 9 includes a high pressure inlet D3, a pressure relief outlet D4, a low pressure inlet E3 and a boost outlet E4. As shown in Figures 3 and 4, wherein, the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 communicates with the high-pressure inlet D3 of the second energy recovery unit 9, and the high pressure inlet D3 of the second energy recovery unit 9 The pressure relief outlet D4 is in communication with the raw water pipeline, so that the concentrated water from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 is depressurized in the second energy recovery unit 9 and then merges with the raw water.

The reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 is also communicated with the low-pressure inlet E3 of the second energy recovery unit 9, and the pressurized outlet E4 of the second energy recovery unit 9 is connected with the third reverse osmosis unit The reverse osmosis inlet A3 of 3 is connected, so that part of the produced water from the reverse osmosis produced water outlet C1 of the first reverse osmosis unit 1 enters the second energy recovery unit 9 and comes out through the reverse osmosis concentrated water outlet B3 The concentrated water in the second energy recovery unit 9 is pressurized by the energy generated by depressurization, and the brine pressurized by the second energy recovery unit 9 is combined with the brine pressurized by the second high pressure pump 5 All sent to the third reverse osmosis unit 3 for processing.

For this reason, under the situation that the reverse osmosis system of the present invention includes the second energy recovery unit 9, the method of the present invention just comprises: the concentrated water that the reverse osmosis concentrated water outlet B3 of the described 3rd reverse osmosis unit 3 comes out from high pressure The inlet D3 is sent to the second energy recovery unit 9 for pressure relief, and then comes out from the pressure relief outlet D4 and merges with the raw water and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 .

For this reason, the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 is divided into two parts, one part is sent to the second high-pressure pump 5 for pressurization, and the other part is sent to the second energy recovery unit pressurization in 9, preferably, part of the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 sent to the low pressure inlet E3 of the second energy recovery unit 9 is sent to the second high pressure The volume flow ratio of part of the produced water from the reverse osmosis produced water outlet C1 of the first reverse osmosis unit 1 of the pump 5 is 0.4-3:1, preferably 0.8-2.5:1. That is, the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 is divided into two parts, defined as part I and part II, part I is sent to the second energy recovery unit 9, part II Send to the second high pressure pump 5, so that the volume flow ratio of part I and part II is 0.4-3:1, preferably 0.8-2.5:1.

For the method of splitting, for example, the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 can be connected to a three-way pipe, one end of the three-way pipe is connected to the inlet of the second high-pressure pump 5, and the other end is connected to the second energy recovery unit 9 low-pressure inlet E3, so that the diversion of the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 can be realized, and other parts that need to be diverted can also adopt a similar method, which is a conventional method in the field .

According to the present invention, preferably, the volume flow ratio of the brine entering from the high-pressure inlet D3 of the second energy recovery unit 9 and the brine entering from the low-pressure inlet E3 of the second energy recovery unit 9 is 1:0.7- 1.3, preferably 1:0.9-1.1.

According to the present invention, the second energy recovery unit 9 may be an energy recovery device having the above performance, for example, it may be a series product of DWEER Company, or a PX series product of ERI Company. The second energy recovery unit 9 can be equal pressure type or differential pressure type, and it can also have a self-increasing function, especially when the second energy recovery unit 9 with a self-increasing function is adopted, then the following Described second pump 7 just can not adopt.

According to the present invention, the reverse osmosis system may also include a second pump 7, the pressurized outlet E4 of the second energy recovery unit 9 communicates with the inlet of the second pump 7, and the outlet of the second pump 7 communicates with the inlet of the second pump 7. The outlets of the second high-pressure pump 5 are all in communication with the reverse osmosis inlet A3 of the third reverse osmosis unit 3 . Thus, the brine from the boost outlet E4 of the second energy recovery unit 9 can be sent to the second pump 7, and the brine from the outlet of the second pump 7 can be boosted with the second high-pressure pump 5 The final brine is sent to the third reverse osmosis unit 3 together for treatment.

Wherein, the second pump 7 may be a booster pump. The booster pump can be a conventional booster pump in the field, for example, its withstand pressure is 4-10MPa, and its lift is 20-100m.

According to the present invention, preferably, the brine entering from the reverse osmosis inlet A3 of the third reverse osmosis unit 3 has a pressure of 1-7 MPa.

The present invention will be described in detail below by way of examples.

In the following example:

The reverse osmosis system shown in Figure 2 comprises: a first reverse osmosis unit 1, a second reverse osmosis unit 2, a third reverse osmosis unit 3, a first high pressure pump 4, a second high pressure pump 5, a first booster pump 6 and The first energy recovery unit 8; the first reverse osmosis unit 1 includes a reverse osmosis inlet A1, a reverse osmosis concentrated water outlet B1 and a reverse osmosis product water outlet C1, and the second reverse osmosis unit 2 includes a reverse osmosis inlet A2, reverse osmosis Permeate concentrated water outlet B2 and reverse osmosis product water outlet C2, the third reverse osmosis unit 3 includes reverse osmosis inlet A3, reverse osmosis concentrated water outlet B3 and reverse osmosis product water outlet C3; the first energy recovery unit 8 includes The connection relationship of the high pressure inlet D1, the pressure relief outlet D2, the low pressure inlet E1 and the booster outlet E2 is shown in Fig. 2 .

The reverse osmosis system shown in Figure 4 comprises: a first reverse osmosis unit 1, a second reverse osmosis unit 2, a third reverse osmosis unit 3, a first high pressure pump 4, a second high pressure pump 5, a first booster pump 6, The second booster pump 7, the first energy recovery unit 8 and the second energy recovery unit 9; the first reverse osmosis unit 1 includes a reverse osmosis inlet A1, a reverse osmosis concentrated water outlet B1 and a reverse osmosis product water outlet C1, so The second reverse osmosis unit 2 includes a reverse osmosis inlet A2, a reverse osmosis concentrated water outlet B2 and a reverse osmosis product water outlet C2, and the third reverse osmosis unit 3 includes a reverse osmosis inlet A3, a reverse osmosis concentrated water outlet B3 and a reverse osmosis Produced water outlet C3; the first energy recovery unit 8 includes a high-pressure inlet D1, a pressure relief outlet D2, a low-pressure inlet E1, and a booster outlet E2, and the second energy recovery unit 9 includes a high-pressure inlet D3, a pressure relief outlet D4, The connection relationship between the low-pressure inlet E3 and the supercharging outlet E4 is shown in Figure 4.

The reverse osmosis system shown in Figure 5 comprises: a first reverse osmosis unit 1, a second reverse osmosis unit 2, a third reverse osmosis unit 3 and a high pressure pump 4, and the first reverse osmosis unit 1 includes a reverse osmosis inlet A1 , reverse osmosis concentrated water outlet B1 and reverse osmosis product water outlet C1, the second reverse osmosis unit 2 includes reverse osmosis inlet A2, reverse osmosis concentrated water outlet B2 and reverse osmosis product water outlet C2, the third reverse osmosis unit 3 includes a reverse osmosis inlet A3, a reverse osmosis concentrated water outlet B3 and a reverse osmosis produced water outlet C3, wherein the inlet of the high-pressure pump 4 is connected to the raw water pipeline, and the outlet is connected to the reverse osmosis inlet A1 of the first reverse osmosis unit 1, The reverse osmosis concentrated water outlet B1 communicates with the reverse osmosis inlet A2 of the second reverse osmosis unit 2, and the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit 2 communicates with the reverse osmosis inlet of the third reverse osmosis unit 3. A3 is connected, wherein the reverse osmosis product water outlets C1, C2 and C3 converge to obtain the system product water, and the water discharged from the reverse osmosis concentrated water outlet B3 is used as the system concentrated water.

The reverse osmosis system shown in Figure 6 comprises: the first reverse osmosis unit 1, the second reverse osmosis unit 2, the third reverse osmosis unit 3 and 3 high-pressure pumps 4, and the first reverse osmosis unit 1 includes a reverse osmosis inlet A1 , reverse osmosis concentrated water outlet B1 and reverse osmosis product water outlet C1, the second reverse osmosis unit 2 includes reverse osmosis inlet A2, reverse osmosis concentrated water outlet B2 and reverse osmosis product water outlet C2, the third reverse osmosis unit 3 includes a reverse osmosis inlet A3, a reverse osmosis concentrated water outlet B3 and a reverse osmosis produced water outlet C3, wherein the inlet of a high-pressure pump 4 is connected to the raw water pipeline, and the outlet is connected to the reverse osmosis inlet A1 of the first reverse osmosis unit 1 , the reverse osmosis product water outlet C1 communicates with the inlet of another high-pressure pump 4, the high-pressure pump outlet communicates with the reverse osmosis inlet A2 of the second reverse osmosis unit 2, and the reverse osmosis product water outlet of the second reverse osmosis unit 2 C2 communicates with the inlet of another high-pressure pump 4, and the outlet of the high-pressure pump communicates with the reverse osmosis inlet A3 of the third reverse osmosis unit 3, wherein the reverse osmosis concentrated water outlets B1, B2 and B3 merge to obtain system concentrated water , and the water discharged from the reverse osmosis product water outlet C3 is used as the system product water.

The first reverse osmosis unit 1 is a reverse osmosis unit configured to have an apparent rejection of 50%.

The second reverse osmosis unit 2 is a reverse osmosis unit configured with an apparent rejection of 31%.

The third reverse osmosis unit 3 is a reverse osmosis unit configured to have an apparent rejection of 99%.

The first energy recovery unit 8 is an iSave-21 energy recovery device purchased from Danfoss.

The second energy recovery unit 9 is an iSave-21 energy recovery device purchased from Danfoss.

Example 1

This embodiment is used to illustrate the reverse osmosis treatment method and reverse osmosis system containing brine of the present invention.

Using the system shown in Figure 4, the brine to be treated is used as raw water and the brine (defined as brine 1#) coming out of the pressure relief outlet D4 of the second energy recovery unit 9 and the reverse osmosis product water of the second reverse osmosis unit 2 The produced water (defined as brine 2#) coming out of outlet C2 merges, wherein, a part of the merged brine (defined as brine 3#) is sent to the first energy recovery unit 8 for pressurization, and another part of the merged brine (defined as The brine 4#) is sent to the first high-pressure pump 4 for boosting, so that the brine (with a pressure of 5.0 MPa) from the booster outlet E2 of the first energy recovery unit 8 is boosted by the first booster pump 6 (with a pressure of 5.8 MPa) MPa) enters the first reverse osmosis unit 1 after joining the brine after the pressurization of the first high pressure pump 4 (the pressure of the brine (defined as brine 5#) entered by the reverse osmosis inlet A1 of the first reverse osmosis unit 1 is 5.8 MPa);

The concentrated water (defined as brine 6#, with a pressure of 5.5MPa) coming out of the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1 is sent to the second reverse osmosis unit 2 for processing, from the second reverse osmosis unit 2 The product water from the reverse osmosis product water outlet C2 is circulated as described above; High pressure inlet D1, and after pressure relief, it comes out from pressure relief outlet D2 as system concentrated water to discharge the system.

The product water (defined as brine 7#) from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 is divided into two parts, and one part (defined as brine 8#) enters from the low-pressure inlet E3 of the second energy recovery unit 9 In the second energy recovery unit 9, pressurize, and the other part is sent to the second high pressure pump 5 for pressurization, and the brine (with a pressure of 5.0MPa) coming out from the boost outlet E4 of the second energy recovery unit 9 is processed by the second booster. After the pressurized pump 7 is pressurized (at a pressure of 6 MPa), it merges with the brine after the pressurization of the second high-pressure pump 5, and sends the combined brine to the third reverse osmosis unit 3 (entered by the reverse osmosis inlet A3 of the third reverse osmosis unit 3 The pressure of the brine is 6MPa);

The concentrated water (with a pressure of 5.7 MPa) coming out of the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 enters the second energy recovery unit 9 from the high-pressure inlet D3 of the second energy recovery unit 9 to release the pressure. After the pressure release Then, the brine coming out of the pressure relief outlet D4 of the second energy recovery unit 9 is circulated as above.

The water from the reverse osmosis product water C3 of the third reverse osmosis unit 3 is discharged from the system as system product water.

For every ton of brine to be treated, the energy consumption of the reverse osmosis system is 13 kWh.

Among them, the volume flow and NaCl concentration of raw water, brine 1#, 2#, 3#, 4#, 5#, 6#, 7#, 8#, system product water and system concentrated water are shown in Table 1.

Table 1

Example 2

This embodiment is used to illustrate the reverse osmosis treatment method and reverse osmosis system containing brine of the present invention.

Using the system shown in Figure 2, different from the system used in Embodiment 1, the system does not have the second energy recovery unit 9 and the second booster pump 7, thus, the implementation process of this embodiment includes:

The brine to be treated is used as the raw water and the brine (defined as brine 1#) from the concentrated water outlet B3 of the third reverse osmosis unit 3 and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 (defined as As brine 2#) confluence, wherein, a part of the confluent brine (defined as brine 3#) is sent to the first energy recovery unit 8 for pressurization, and another part of the confluent brine (defined as brine 4#) is sent to the first energy recovery unit 8 A high-pressure pump 4 pressurizes, so that the brine (with a pressure of 5.0 MPa) coming out of the boost outlet E2 of the first energy recovery unit 8 passes through the first booster pump 6 and merges with the brine boosted by the first high-pressure pump 4 to enter In the first reverse osmosis unit 1 (the pressure of the brine (defined as brine 5#) entering by the reverse osmosis inlet A1 of the first reverse osmosis unit 1 is 5.8MPa);

The concentrated water (defined as brine 6#) from the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit 1 is sent to the second reverse osmosis unit 2 for treatment, and the reverse osmosis product water outlet of the second reverse osmosis unit 2 The product water that C2 comes out is circulated as described above; The concentrated water (pressure is 5.2MPa) that the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit 2 comes out is sent to the high-pressure inlet D1 of the first energy recovery unit 8, and After pressure relief, it comes out from the pressure relief outlet D2 as system concentrated water and is discharged out of the system.

The product water (defined as brine 7#) from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1 is all sent to the second high-pressure pump 5 for pressurization, and then sent to the third reverse osmosis unit 3 (from the first reverse osmosis unit 3 after the pressurization) The pressure of the brine that the reverse osmosis inlet A3 of three reverse osmosis units 3 enters is 6.0MPa) in processing;

The concentrated water from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 is directly merged into the raw water pipeline for circulation as above.

The water from the reverse osmosis product water C3 of the third reverse osmosis unit 3 is discharged from the system as system product water.

For every ton of brine to be treated, the energy consumption of the reverse osmosis system is 17 kWh.

Among them, the volume flow and NaCl concentration of raw water, brine 1#, 2#, 3#, 4#, 5#, 6#, 7#, system product water and system concentrated water are shown in Table 2.

Table 2

Comparative example 1

Using the reverse osmosis system shown in Figure 5, the brine to be treated is sent to a high-pressure pump 4 as raw water to be pressurized to 6MPa, and then sent to the first reverse osmosis unit 1, from the reverse osmosis of the first reverse osmosis unit 1 The concentrated water from the concentrated water outlet B1 is sent to the second reverse osmosis unit 2, and the concentrated water from the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit 2 is sent to the third reverse osmosis unit 3, and the concentrated water from the second reverse osmosis unit 2 The concentrated water from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 is used as the concentrated water discharge system of the system, the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit 1, the reverse osmosis unit 2 of the second reverse osmosis unit 2 The product water from the permeate product water outlet C2 and the product water from the reverse osmosis product water outlet C3 of the third reverse osmosis unit 3 are combined as the system product water discharge system.

Among them, the volume flow and NaCl concentration of raw water, system product water and system concentrated water are shown in Table 3.

table 3

Comparative example 2

Using the reverse osmosis system shown in Figure 6, the brine to be treated is sent to a high-pressure pump 4 as raw water to be pressurized to 6MPa, and then sent to the first reverse osmosis unit 1, from the reverse osmosis of the first reverse osmosis unit 1 The product water from the product water outlet C1 is sent to a high-pressure pump 4 to pressurize to 6MPa, and then sent to the second reverse osmosis unit 2, and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit 2 is sent to To a high-pressure pump 4 to pressurize to 6MPa, and then sent to the third reverse osmosis unit 3, the product water from the reverse osmosis product water outlet C3 of the third reverse osmosis unit 3 is discharged from the system as system product water, from the first The concentrated water from the reverse osmosis concentrated water outlet B1 of the reverse osmosis unit 1, the concentrated water from the reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit 2, and the concentrated water from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit 3 The water confluence serves as the system concentrated water discharge system.

Among them, the volume flow and NaCl concentration of raw water, system product water and system concentrated water are shown in Table 4.

Table 4

It can be seen that the reverse osmosis system and method of the present invention can break through the concentration limit of the traditional reverse osmosis system, ensure the water quality of the system produced water, effectively reduce the use of high-pressure pumps in the combined system, simplify the system design, and reduce the investment of the combined system cost. The present invention also adds an energy recovery unit to the combined reverse osmosis system to recover and convert the unused residual energy in the system, thereby further reducing the energy consumption of the system.

The preferred embodiments of the present invention have been described in detail above, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (13)

1. a reverse osmosis system, is characterized in that, this reverse osmosis system comprises: the first reverse osmosis unit (1), the second reverse osmosis unit (2), the 3rd reverse osmosis unit (3), the first high pressure pump ( 4), the second high-pressure pump (5) and the first energy recovery unit (8); the first reverse osmosis unit (1) includes a reverse osmosis inlet A1, a reverse osmosis concentrated water outlet B1 and a reverse osmosis product water outlet C1, The second reverse osmosis unit (2) includes a reverse osmosis inlet A2, a reverse osmosis concentrated water outlet B2 and a reverse osmosis produced water outlet C2, and the third reverse osmosis unit (3) includes a reverse osmosis inlet A3, a reverse osmosis concentrated water outlet Outlet B3 and reverse osmosis water production outlet C3; the first energy recovery unit (8) includes a high pressure inlet D1, a pressure relief outlet D2, a low pressure inlet E1 and a booster outlet E2; Wherein, the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit (1) communicates with the reverse osmosis inlet A2 of the second reverse osmosis unit (2), so that the first reverse osmosis unit (1) The concentrated water coming out of the reverse osmosis concentrated water outlet B1 enters the second reverse osmosis unit (2) for processing; The reverse osmosis concentrated water outlet B2 of the second reverse osmosis unit (2) communicates with the high-pressure inlet D1 of the first energy recovery unit (8), so that the reverse osmosis concentrated water of the second reverse osmosis unit (2) The concentrated water coming out of the water outlet B2 is decompressed through the first energy recovery unit (8); The reverse osmosis produced water outlet C1 of the first reverse osmosis unit (1) communicates with the inlet of the second high-pressure pump (5), and the outlet of the second high-pressure pump (5) communicates with the third reverse osmosis unit (3) ) connected to the reverse osmosis inlet A3, so that the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit (1) enters the third reverse osmosis unit (3) for treatment after being pressurized ; The reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit (3) and the reverse osmosis product water outlet C2 of the second reverse osmosis unit (2) are communicated with the raw water pipeline, so that the third reverse osmosis unit ( 3) The concentrated water from the reverse osmosis concentrated water outlet B3 and the product water from the reverse osmosis product water outlet C2 of the second reverse osmosis unit (2) are merged with the raw water; The raw water pipeline is respectively communicated with the inlet of the first high-pressure pump (4) and the low-pressure inlet E1 of the first energy recovery unit (8), and the pressurized outlet E2 of the first energy recovery unit (8) is connected with the The outlets of the first high-pressure pump (4) are all communicated with the reverse osmosis inlet A1 of the first reverse osmosis unit (1), so that part of the brine in the raw water pipeline enters the first energy recovery unit (8) to utilize reverse osmosis The concentrated water from the concentrated water outlet B2 is pressurized by the energy generated by the pressure release in the first energy recovery unit (8), while another part of the brine in the raw water pipeline is pressurized by the first high-pressure pump (4), and The brine after the pressurization of the first energy recovery unit (8) and the pressurization of the first high-pressure pump (4) is sent to the first reverse osmosis unit (1) for treatment. 2. reverse osmosis system according to claim 1, wherein, this reverse osmosis system also comprises the second energy recovery unit (9), and described second energy recovery unit (9) comprises high pressure inlet D3, pressure relief outlet D4, Low pressure inlet E3 and supercharged outlet E4; Wherein, the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit (3) communicates with the high-pressure inlet D3 of the second energy recovery unit (9), and the pressure relief outlet of the second energy recovery unit (9) D4 is communicated with the raw water pipeline, so that the concentrated water from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit (3) is depressurized in the second energy recovery unit (9) and then merged with the raw water ; The reverse osmosis product water outlet C1 of the first reverse osmosis unit (1) is also communicated with the low-pressure inlet E3 of the second energy recovery unit (9), and the pressurized outlet E4 of the second energy recovery unit (9) It communicates with the reverse osmosis inlet A3 of the third reverse osmosis unit (3), so that part of the produced water from the reverse osmosis produced water outlet C1 of the first reverse osmosis unit (1) enters the second energy recovery unit In (9), the concentrated water coming out of the reverse osmosis concentrated water outlet B3 is pressurized by the energy generated by the pressure relief in the second energy recovery unit (9), and the second energy recovery unit (9) is pressurized Both the brine and the brine pressurized by the second high-pressure pump (5) are sent to the third reverse osmosis unit (3) for processing. 3. The reverse osmosis system according to claim 1 or 2, wherein the apparent rejection rate of the first reverse osmosis unit (1) is 20-80%, and the apparent rejection rate of the second reverse osmosis unit (2) is The apparent rejection rate is 20-80%, and the apparent rejection rate of the third reverse osmosis unit (3) is more than 90%; Preferably, the apparent rejection rate of the first reverse osmosis unit (1) is 40-70%, the apparent rejection rate of the second reverse osmosis unit (2) is 25-50%, and the third reverse osmosis unit (2) has an apparent rejection rate of 25-50%. The apparent rejection rate of the permeation unit (3) is above 95%. 4. The reverse osmosis system according to any one of claims 1-3, wherein the reverse osmosis system also comprises a first pump (6), and the pressurized outlet E2 of the first energy recovery unit (8) is connected to The inlet of the first pump (6) is communicated, and the outlet of the first pump (6) and the outlet of the first high-pressure pump (4) are all communicated with the reverse osmosis inlet A1 of the first reverse osmosis unit (1) ; Preferably, the first pump (6) is a booster pump. 5. The reverse osmosis system according to claim 2, wherein the reverse osmosis system also comprises a second pump (7), and the pressurized outlet E4 of the second energy recovery unit (9) is connected to the second pump ( 7) is communicated with the inlet, and the outlet of the second pump (7) and the outlet of the second high pressure pump (5) are all communicated with the reverse osmosis inlet A3 of the third reverse osmosis unit (3); Preferably, the second pump (7) is a booster pump. 6. A kind of reverse osmosis treatment method containing brine, it is characterized in that, the method is carried out in the reverse osmosis system, and described reverse osmosis system comprises: the first reverse osmosis unit (1), the second reverse osmosis unit (2), The third reverse osmosis unit (3), the first high pressure pump (4), the second high pressure pump (5) and the first energy recovery unit (8); the first reverse osmosis unit (1) includes reverse osmosis inlet A1, Reverse osmosis concentrated water outlet B1 and reverse osmosis product water outlet C1, the second reverse osmosis unit (2) includes reverse osmosis inlet A2, reverse osmosis concentrated water outlet B2 and reverse osmosis product water outlet C2, the third reverse osmosis The unit (3) includes a reverse osmosis inlet A3, a reverse osmosis concentrated water outlet B3 and a reverse osmosis product water outlet C3; the first energy recovery unit (8) includes a high-pressure inlet D1, a pressure relief outlet D2, a low-pressure inlet E1 and a pressurized Exit E2; The method comprises: using the brine to be treated as raw water and the concentrated water from the concentrated water outlet B3 of the third reverse osmosis unit (3) and the product produced from the reverse osmosis product water outlet C2 of the second reverse osmosis unit (2). The water is sent to the first high-pressure pump (4) together to increase the pressure; and the raw water is optionally mixed with the concentrated water from the third reverse osmosis unit (3) and/or the reverse osmosis of the second reverse osmosis unit (2) Part of the brine after the combined product water from the product water outlet C2 is sent to the low-pressure inlet E1 of the first energy recovery unit (8) for pressurization, and then the brine from the pressurized outlet of the first energy recovery unit (8) The salt water from E2 is sent to the first reverse osmosis unit (1) together with the salt water pressurized by the first high-pressure pump (4) for processing; The concentrated water coming out of the reverse osmosis concentrated water outlet B1 of the first reverse osmosis unit (1) is sent to the second reverse osmosis unit (2) for processing, and the reverse osmosis unit (2) of the second reverse osmosis unit (2) is The concentrated water from the permeated concentrated water outlet B2 is sent to the high-pressure inlet D1 of the first energy recovery unit (8) to release pressure in the first energy recovery unit (8), and then from the first energy recovery unit ( 8) The pressure relief outlet D2 comes out and is discharged as system concentrated water; The product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit (1) is sent to the third reverse osmosis unit (3) for treatment after being pressurized by the second high-pressure pump (5), and will be processed from the The produced water from the reverse osmosis product outlet C3 of the third reverse osmosis unit (3) is discharged as system product water. 7. The method according to claim 6, wherein the reverse osmosis system further comprises a second energy recovery unit (9), and the second energy recovery unit (9) comprises a high pressure inlet D3, a pressure relief outlet D4, a low pressure inlet E3 and supercharging outlet E4; The method also includes: sending the concentrated water from the reverse osmosis concentrated water outlet B3 of the third reverse osmosis unit (3) to the second energy recovery unit (9) from the high-pressure inlet D3 for pressure relief, and then from The pressure relief outlet D4 comes out and merges with the raw water and the product water coming out of the reverse osmosis product water outlet C2 of the second reverse osmosis unit (2); The product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit (1) is divided into two parts, one part is sent to the second high-pressure pump (5) for pressurization, and the other part enters the Pressurize in the second energy recovery unit (9), then discharge from the pressurization outlet E4 and send to the third reverse osmosis unit (3) for processing together with the brine after the pressurization of the second high-pressure pump (5); Preferably, part of the product water from the reverse osmosis product water outlet C1 of the first reverse osmosis unit (1) sent to the low-pressure inlet E3 of the second energy recovery unit (9) is sent to the second high-pressure pump (5) The volume flow ratio of the part of the produced water from the reverse osmosis produced water outlet C1 of the first reverse osmosis unit (1) is 0.4-3:1, preferably 0.8-2.5:1. 8. The method according to claim 6 or 7, wherein the apparent rejection rate of the first reverse osmosis unit (1) is 20-80%, and the apparent rejection rate of the second reverse osmosis unit (2) The rate is 20-80%, and the apparent rejection rate of the third reverse osmosis unit (3) is more than 90%; Preferably, the apparent rejection rate of the first reverse osmosis unit (1) is 40-70%, the apparent rejection rate of the second reverse osmosis unit (2) is 25-50%, and the third reverse osmosis unit (2) has an apparent rejection rate of 25-50%. The apparent rejection rate of the permeation unit (3) is above 95%. 9. The method according to any one of claims 6-8, wherein the reverse osmosis system further comprises a first pump (6), the method comprises: boosting the first energy recovery unit (8) The brine from the outlet E2 is sent to the first pump (6), and the brine from the outlet of the first pump (6) is sent to the first reactor together with the brine pressurized by the first high-pressure pump (4). Process in the osmosis unit (1); Preferably, the first pump (6) is a booster pump. 10. The method according to claim 7, wherein the reverse osmosis system further comprises a second pump (7), the method comprises: sending the brine that comes out of the pressurized outlet E4 of the second energy recovery unit (9) to to the second pump (7), and the brine from the outlet of the second pump (7) is sent to the third reverse osmosis unit (3) together with the brine after the pressurization of the second high pressure pump (5) process; Preferably, the second pump (7) is a booster pump. 11. according to the method described in any one in claim 6-10, wherein, the brine pressure that enters from the reverse osmosis inlet A1 of described first reverse osmosis unit (1) is 4-7MPa, from described second reverse osmosis The pressure of the brine entering from the reverse osmosis inlet A2 of the osmosis unit (2) is 4-7MPa, and the pressure of the brine entering from the reverse osmosis inlet A3 of the third reverse osmosis unit (3) is 1-7MPa. 12. The method according to any one of claims 6-11, wherein the brine entering from the high-pressure inlet D1 of the first energy recovery unit (8) and the brine from the first energy recovery unit (8) The volume flow ratio of the brine entering the low-pressure inlet E1 is 1:0.7-1.3, preferably 1:0.9-1.1. 13. The method according to claim 7 or 10, wherein the brine entering from the high-pressure inlet D3 of the second energy recovery unit (9) and the brine entering from the low-pressure inlet E3 of the second energy recovery unit (9) The volume flow ratio of the brine is 1:0.7-1.3, preferably 1:0.9-1.1.