A high-concentration brine concentration reduction system and method

Abstract

The present invention belongs to the field of high-concentration brine treatment, and discloses a high-concentration brine concentration reduction system and method. The system includes a pretreatment unit, a SWRO spiral wound reverse osmosis unit, and at least one stage of tubular membrane concentration reduction unit. The technology of the present invention breaks through the traditional concept of continuously increasing the operating pressure to pursue a higher concentration limit, and replaces one-step concentration with gradient concentration, which is a high-concentration brine high-fold concentration technology with low cost and low energy consumption.

Description

Technical Field

[0001] The present invention belongs to the field of high-concentration brine treatment, and more specifically, relates to a high-concentration brine concentration and reduction system and method. Background Art

[0002] In recent years, with the advancement of relevant policies on sewage resource utilization, the recycling of industrial wastewater has emerged, with a water recovery rate of up to 95%-99%. On the one hand, it is of great significance to water pollution control and wastewater resource utilization; on the other hand, a large amount of highly concentrated brine has been produced, such as reverse osmosis concentrated brine. Highly concentrated brine cannot be discharged directly, and generally requires near-zero discharge. Its process flow is usually "pretreatment + membrane concentration and reduction + evaporation and crystallization". Since the investment and operating costs of the project are mainly concentrated in the evaporation and crystallization unit, how to reduce the processing scale of the evaporation and crystallization unit has always been the focus of the industry. The fresh water of the membrane concentration and reduction unit directly determines the water quality and quantity of the recycled water, and the concentrated water determines the equipment investment and operating energy consumption of the subsequent evaporation and crystallization unit. Therefore, it is crucial to optimize the membrane concentration and reduction unit.

[0003] The purpose of the high-concentration brine membrane concentration and reduction unit is to increase the TDS of the brine as much as possible, reduce the amount of water entering the evaporation and crystallization unit, reduce the scale of the evaporation crystallizer, and reduce investment and operating costs. The membrane concentration and reduction methods involved include ultra-high pressure reverse osmosis, disc-tube reverse osmosis, forward osmosis, membrane distillation and electrodialysis. Among them:

[0004] Ultra-high pressure reverse osmosis and disc-tube reverse osmosis are both based on pressure-driven membrane processes. The osmotic pressure of sodium chloride at 25°C is 60 bar (concentration 115 g / L) and 120 bar (concentration 140 g / L). Considering the influence of concentration polarization and temperature, in actual tests, the reverse osmosis membrane pressure must be 10 bar greater than the osmotic pressure of the concentrate to effectively concentrate. Therefore, the use of reverse osmosis membranes to concentrate highly concentrated brine requires ultra-high pressure, which means high energy consumption, high system cost and high operational safety risks.

[0005] Forward osmosis can be regarded as an engineered osmosis process, which uses a driving liquid to extract, does not require external pressure as a driving force, and has low energy consumption. The disadvantage is that the driving liquid is difficult to recycle;

[0006] Membrane distillation combines membrane technology with traditional distillation technology. It is an evaporation and condensation process with phase change and low-temperature operation. It is not limited by osmotic pressure and has a high concentration multiple. Raw water heating can use low-grade heat such as waste heat from the plant to further reduce energy consumption. However, disadvantages also exist. There is phase change, and the latent heat of vaporization reduces energy utilization. The membrane flux is small, and the higher the concentration, the smaller the flux. At the same time, there is a risk of wetting of the membrane element.

[0007] Electrodialysis ED. Electrodialysis is suitable for concentrating highly concentrated saline wastewater. The TDS can be concentrated up to 150,000 - 200,000 mg / L at most. It has a low operating pressure and good corrosion resistance. However, the commonly used membrane module form at present is flat plate type, with a small packing density, a large floor area, a relatively high power consumption, and it is prone to generate uneven flow due to the influence of pressure difference during operation.

[0008] Among the above-mentioned membrane concentration and reduction methods, the relatively mature processes are reverse osmosis and electrodialysis. Considering from the perspectives of investment and operating costs, reverse osmosis has greater advantages. In order to meet the requirements of "near-zero discharge" of industrial wastewater for high-fold concentration and reduction processes, traditional reverse osmosis continuously increases the operating pressure to pursue a higher concentration limit. The increase in operating pressure means high energy consumption, high fixed investment (in order to withstand high pressure, the membrane system accessories and peripheral facilities including pressure membrane shells, pipelines, and joints must be made of high-pressure-resistant materials), and membrane fouling. Therefore, it is of great significance to seek a high-concentration brine concentration and reduction process with low operating pressure, low energy consumption, and low cost. Summary of the Invention

[0009] The purpose of the present invention is to address the deficiencies of the prior art and propose a high-concentration brine concentration and reduction system and method. The technology of the present invention breaks through the traditional concept of continuously increasing the operating pressure to pursue a higher concentration limit, and replaces one-step concentration with gradient concentration. It is a high-fold concentration technology for high-concentration brine with low cost and low energy consumption.

[0010] To achieve the above purpose, on the one hand, the present invention provides a high-concentration brine concentration and reduction system, which includes a pretreatment unit, a SWRO spiral wound reverse osmosis unit, and at least one-stage tubular membrane concentration and reduction unit;

[0011] The pretreatment unit is provided with a pretreatment water tank; the pretreatment water tank is connected with a water inlet pipe, a water outlet pipe, and a water return pipe;

[0012] When the system is provided with multiple-stage tubular membrane concentration and reduction units, each stage of tubular membrane concentration and reduction units is connected in series in turn; each stage of tubular membrane concentration and reduction unit is provided with a tubular membrane module, and the tubular membrane module is provided with a primary permeate outlet pipeline and a primary concentrate outlet pipeline;

[0013] The SWRO spiral wound reverse osmosis unit is provided with a spiral wound membrane module SWRO; the spiral wound membrane module SWRO is provided with a secondary permeate outlet pipeline and a secondary concentrate outlet pipeline;

[0014] The water outlet pipe is connected with the first-stage tubular membrane concentration and reduction unit;

[0015] The primary permeate outlet pipeline of the first-stage tubular membrane concentration and reduction unit is connected with the SWRO spiral wound reverse osmosis unit;

[0016] The outlet pipeline of the first-stage concentrated liquid of the first-stage network tube type membrane concentration and reduction unit is connected to the evaporation crystallization system or to the second-stage network tube type membrane concentration and reduction unit;

[0017] The outlet pipeline of the secondary permeate is connected to the outside of the system;

[0018] The outlet pipeline of the secondary concentrated liquid is connected to the return water pipe.

[0019] According to the present invention, preferably, each stage of the network tube type membrane concentration and reduction unit is provided with a first security filter, a first high-pressure pump and the network tube type membrane module connected in sequence; the first-stage network tube type membrane concentration and reduction unit is further provided with a first booster pump, and the water outlet pipe is connected to the first security filter of the first booster pump and the first-stage network tube type membrane concentration and reduction unit in sequence.

[0020] According to the present invention, preferably, the SWRO spiral wound reverse osmosis unit is provided with an intermediate water tank, a second booster pump, a second security filter and a second high-pressure pump connected in sequence; the spiral wound membrane module SWRO is provided with a SWRO water inlet; the outlet pipeline of the first-stage permeate of the first-stage network tube type membrane concentration and reduction unit is connected to the intermediate water tank; the second high-pressure pump is connected to the SWRO water inlet.

[0021] According to the present invention, preferably, the first security filter is a core filter and / or a precision filter; the filtration accuracy of the first security filter is 10-100um.

[0022] According to the present invention, preferably, the second security filter is a core filter or a precision filter; the filtration accuracy of the second security filter is 5-50um.

[0023] According to the present invention, preferably, when two stages of network tube type membrane concentration and reduction units are provided in the system, the outlet pipeline of the first-stage concentrated liquid of the first-stage network tube type membrane concentration and reduction unit is connected to the inlet of the first security filter of the second-stage network tube type membrane concentration and reduction unit;

[0024] The outlet pipeline of the first-stage permeate of the second-stage network tube type membrane concentration and reduction unit is connected to the return water pipe; the outlet pipeline of the first-stage concentrated liquid of the second-stage network tube type membrane concentration and reduction unit is connected to the evaporation crystallization system.

[0025] According to the present invention, preferably, when three stages of network tube type membrane concentration and reduction units are provided in the system, the outlet pipeline of the first-stage concentrated liquid of the first-stage network tube type membrane concentration and reduction unit is connected to the inlet of the first security filter of the second-stage network tube type membrane concentration and reduction unit;

[0026] The first permeate outlet pipeline of the second-stage network tube type membrane concentration and reduction unit is connected to the return water pipe; the first concentrated liquid outlet pipeline of the second-stage network tube type membrane concentration and reduction unit is connected to the inlet of the first security filter of the third-stage network tube type membrane concentration and reduction unit;

[0027] The first permeate outlet pipeline of the third-stage network tube type membrane concentration and reduction unit is connected to the inlet of the first security filter of the second-stage network tube type membrane concentration and reduction unit; the first concentrated liquid outlet pipeline of the third-stage network tube type membrane concentration and reduction unit is connected to the evaporation and crystallization system.

[0028] According to the present invention, preferably, a first concentrated water flow regulating valve is provided on the first concentrated liquid outlet pipeline. By adjusting the opening degree of the first concentrated water flow regulating valve, the pressure and the concentrated liquid flow rate in the membrane module can be controlled, and the water recovery rate required by the system can be achieved simultaneously.

[0029] According to the present invention, preferably, the network tube type membrane module includes at least one network tube type membrane column; when the network tube type membrane module includes multiple network tube type membrane columns, the multiple network tube type membrane columns are connected in series;

[0030] Each network tube type membrane column is provided with a separation membrane element, and the salt permeability of the separation membrane element is 30%-40%;

[0031] Preferably, the network tube type membrane module includes 1-8 network tube type membrane columns.

[0032] In the present invention, the separation membrane element adopted by the network tube type membrane module of the present invention has a high salt permeability coefficient. The high salt permeability coefficient of the separation membrane element can reduce the osmotic pressure on both sides of the membrane, thereby reducing the operating pressure of the membrane system and realizing the function of extreme concentration; preferably, the network tube type membrane module DTL (purchased from Luxin Tiandi Ren Environmental Technology (Anhui) Group Co., Ltd.) is selected for the network tube type membrane module of the present invention. The membrane module structure of the network tube type membrane module DTL adopts an open parallel grid, has low requirements for pretreatment, strong anti-pollution ability, has anti-pollution characteristics and a large single membrane area, can effectively avoid membrane fouling and scaling, has a lower membrane cost per ton of water, and at the same time, the membrane module structure of the network tube type membrane module DTL can withstand a higher operating pressure (such as 75 bar / 90 bar).

[0033] The spiral wound membrane module SWRO of the present invention can realize the recovery of end salts and the improvement of water quality.

[0034] According to the present invention, preferably, a second concentrated water flow regulating valve is provided on the second concentrated liquid outlet pipeline. By adjusting the opening degree of the second concentrated water flow regulating valve, the pressure and the concentrated liquid flow rate in the SWRO spiral wound reverse osmosis unit can be controlled, and the water production quality required by the system can be achieved simultaneously.

[0035] According to the present invention, preferably, the spiral wound membrane module SWRO includes at least one spiral wound reverse osmosis membrane column; when the spiral wound membrane module SWRO includes multiple spiral wound reverse osmosis membrane columns, the multiple spiral wound reverse osmosis membrane columns are connected in series;

[0036] Preferably, the spiral wound membrane module SWRO includes 1-6 spiral wound reverse osmosis membrane columns.

[0037] On the other hand, the present invention provides a method for concentrating and reducing the amount of high-concentration brine. The method uses the system described above and includes the following steps:

[0038] Feed the high-concentration brine from the pretreatment water tank into the first-stage tubular membrane concentration and reduction unit for treatment to obtain a first-stage primary permeate and a first-stage primary concentrate;

[0039] Send the first-stage primary concentrate to the evaporation crystallization system or to the second-stage tubular membrane concentration and reduction unit;

[0040] Feed the first-stage primary permeate into the SWRO spiral wound reverse osmosis unit for treatment to obtain a secondary permeate and a secondary concentrate; discharge the secondary permeate and return the secondary concentrate to the pretreatment water tank.

[0041] According to the present invention, preferably, the TDS of the high-concentration brine is 61000-75000 mg / L.

[0042] According to the present invention, preferably, the TDS of the secondary permeate is 90-250 mg / L.

[0043] According to the present invention, preferably, the TDS of the first-stage primary concentrate is 115000-145000 mg / L.

[0044] According to the present invention, preferably, the working pressure of each stage of the tubular membrane concentration and reduction unit is 3.5-7.0 Mpa; the water recovery rate of each stage of the tubular membrane concentration and reduction unit is 60%-65%.

[0045] According to the present invention, preferably, the working pressure of the SWRO spiral wound reverse osmosis unit is 3.5-6.5 Mpa; the water recovery rate of the SWRO spiral wound reverse osmosis unit is 70%-80%.

[0046] According to the present invention, preferably, send the first-stage primary concentrate to the second-stage tubular membrane concentration and reduction unit, and after being treated by the second-stage tubular membrane concentration and reduction unit, obtain a second-stage primary permeate and a second-stage primary concentrate;

[0047] Return the second-stage primary permeate to the pretreatment water tank;

[0048] Send the secondary first-stage concentrated liquid to the evaporation crystallization system;

[0049] The TDS of the secondary first-stage concentrated liquid is 155,000 - 165,000 mg / L.

[0050] According to the present invention, preferably, send the primary first-stage concentrated liquid to the second-stage tubular membrane concentration and reduction unit, and after being processed by the second-stage tubular membrane concentration and reduction unit, obtain the secondary first-stage permeate and the secondary first-stage concentrated liquid;

[0051] Return the secondary first-stage permeate to the pretreatment water tank;

[0052] Send the secondary first-stage concentrated liquid to the third-stage tubular membrane concentration and reduction unit, and after being processed by the third-stage tubular membrane concentration and reduction unit, obtain the tertiary first-stage permeate and the tertiary first-stage concentrated liquid;

[0053] Send the tertiary first-stage permeate to the inlet of the first security filter of the second-stage tubular membrane concentration and reduction unit;

[0054] Send the tertiary first-stage concentrated liquid to the evaporation crystallization system;

[0055] The TDS of the tertiary first-stage concentrated liquid is 190,000 - 210,000 mg / L.

[0056] The beneficial effects of the technical solution of the present invention are as follows:

[0057] (1) The present invention is a high-concentration brine high-fold concentration technology with low cost and low energy consumption. Under the reverse osmosis operating pressure conditions of the present invention, the reverse osmosis concentration limit can be increased from the traditional 7% (70,000 mg / L) to 14% (140,000 mg / L), or even higher;

[0058] (2) The operating pressure of the system of the present invention does not exceed 7 MPa, with low energy consumption, and the operating and investment costs are significantly lower than those of secondary concentration technologies such as ultra-high pressure reverse osmosis and disk tube reverse osmosis;

[0059] (3) By adopting a segmented + hierarchical treatment mode, the present invention improves the concentration multiple and the water quality of the produced water, and returns the permeate with a higher salt content to the previous stage (segment), maximizing the concentration and recovery of salts.

[0060] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. Brief Description of the Drawings

[0061] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above and other objects, features, and advantages of the present invention will become more obvious, wherein, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0062] Figure 1 Shows a schematic diagram of a high-concentration brine concentration reduction system provided by the present invention.

[0063] Figure 2 Shows a schematic diagram of a high-concentration brine concentration reduction system provided in Embodiment 1 of the present invention.

[0064] Figure 3 Shows a schematic diagram of a high-concentration brine concentration reduction system provided in Embodiment 2 of the present invention.

[0065] Figure 4 Shows a schematic diagram of a high-concentration brine concentration reduction system provided in Embodiment 3 of the present invention.

[0066] The description of the reference numerals is as follows:

[0067] Pretreatment unit:

[0068] 1 Pretreatment water tank; 2 Inlet pipe; 3 Outlet pipe; 4 Return pipe;

[0069] SWRO spiral wound reverse osmosis unit:

[0070] 5 Intermediate water tank; 6 Second booster pump; 7 Second security filter; 8 Second high-pressure pump; 9 Spiral wound membrane module SWRO; 10 Secondary permeate outlet pipeline; 11 Secondary concentrate outlet pipeline;

[0071] First-stage tubular membrane concentration reduction unit:

[0072] 12 First booster pump; 13 First security filter; 14 First high-pressure pump; 15 Tubular membrane module; 16 First-stage permeate outlet pipeline; 17 First-stage concentrate outlet pipeline;

[0073] First-stage tubular membrane concentration reduction unit:

[0074] 12-1 First booster pump of the first-stage tubular membrane concentration reduction unit; 13-1 First security filter of the first-stage tubular membrane concentration reduction unit; 14-1 First high-pressure pump of the first-stage tubular membrane concentration reduction unit; 15-1 Tubular membrane module of the first-stage tubular membrane concentration reduction unit; 16-1 First-stage permeate outlet pipeline of the first-stage tubular membrane concentration reduction unit; 17-1 First-stage concentrate outlet pipeline of the first-stage tubular membrane concentration reduction unit;

[0075] Second-stage tubular membrane concentration reduction unit:

[0076] The first security filter of the second-stage network tube type membrane concentration and reduction unit; the first high-pressure pump of the second-stage network tube type membrane concentration and reduction unit; the network tube type membrane module of the second-stage network tube type membrane concentration and reduction unit; the first-stage permeate outlet pipeline of the second-stage network tube type membrane concentration and reduction unit; the first-stage concentrated liquid outlet pipeline of the second-stage network tube type membrane concentration and reduction unit;

[0077] The third-stage network tube type membrane concentration and reduction unit:

[0078] The first security filter of the third-stage network tube type membrane concentration and reduction unit; the first high-pressure pump of the third-stage network tube type membrane concentration and reduction unit; the network tube type membrane module of the third-stage network tube type membrane concentration and reduction unit; the first-stage permeate outlet pipeline of the third-stage network tube type membrane concentration and reduction unit; the first-stage concentrated liquid outlet pipeline of the third-stage network tube type membrane concentration and reduction unit;

[0079] 19 The first concentrated water flow regulating valve; 20 The second concentrated water flow regulating valve; 21 The first check valve; 22 The second check valve. Detailed implementation mode

[0080] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0081] In the following various embodiments:

[0082] The network tube type membrane module is the network tube type membrane module DTL, purchased from Luxin Tiandi Ren Environmental Technology (Anhui) Group Co., Ltd., special concentrated water grid: open N-type flow channel; effective membrane area 29.5m 2 ; Pressure rating: 75 bar / 90 bar.

[0083] Embodiment 1

[0084] This embodiment provides a high-concentration brine concentration and reduction system, as Figure 2 shown, the system includes a pretreatment unit, a SWRO spiral wound reverse osmosis unit and a first-stage network tube type membrane concentration and reduction unit;

[0085] The pretreatment unit is provided with a pretreatment water tank 1; the pretreatment water tank is connected with a water inlet pipe 2, a water outlet pipe 3 and a water return pipe 4;

[0086] The one-stage network tube type membrane concentration and reduction unit is provided with a first booster pump 12, a first security filter 13, a first high-pressure pump 14 and a network tube type membrane module 15 which are connected in sequence; the network tube type membrane module 15 is provided with a first-stage permeate outlet pipeline 16 and a first-stage concentrate outlet pipeline 17; the network tube type membrane module 15 includes 6 network tube type membrane columns which are connected in series; each network tube type membrane column is provided with a separation membrane element (not shown), and the salt rejection rate of the separation membrane element is 30%-40%; the first security filter 13 adopts a core type filter with a filtration accuracy of 100um;

[0087] The SWRO spiral wound reverse osmosis unit is provided with an intermediate water tank 5, a second booster pump 6, a second security filter 7, a second high-pressure pump 8 and a spiral wound membrane module SWRO9 which are connected in sequence; the spiral wound membrane module SWRO9 is provided with a second-stage permeate outlet pipeline 10 and a second-stage concentrate outlet pipeline 11; the spiral wound membrane module SWRO9 includes 3 spiral wound reverse osmosis membrane columns which are connected in series; the second security filter 7 adopts a core type filter with a filtration accuracy of 50um;

[0088] The water outlet pipe 3 is connected to the first booster pump 12;

[0089] The first-stage permeate outlet pipeline 16 of the one-stage network tube type membrane concentration and reduction unit is connected to the intermediate water tank 5;

[0090] The first-stage concentrate outlet pipeline 17 of the one-stage network tube type membrane concentration and reduction unit is connected to the evaporation crystallization system;

[0091] The second-stage permeate outlet pipeline 10 is connected to the outside of the system;

[0092] The second-stage concentrate outlet pipeline 11 is connected to the water return pipe.

[0093] This embodiment also provides a method for concentrating and reducing high-concentration brine. The method uses the above system and includes the following steps:

[0094] The high-concentration brine (TDS 64858mg / L) is sent from the pretreatment water tank 1 through the first booster pump 12 (operating pressure 3-4 bar) to the first security filter 13 for treatment. The water output of the first security filter 13 is sent through the first high-pressure pump 14 (operating pressure 65-70 bar) to the inlet of the network tube type membrane module 15 for concentration treatment, obtaining a first-stage first-stage permeate (TDS 24949mg / L) and a first-stage first-stage concentrate (TDS 139741mg / L), and the water recovery rate is 60%-65%;

[0095] Send the first-stage first-stage concentrate to the evaporation crystallization system;

[0096] Feed the said section of the first-stage permeate into the intermediate water tank 5, and pump it into the second security filter 7 by the second booster pump 6 (operating pressure 3 - 4 bar); Next, the water output from the second security filter 7 enters the inlet of the spiral wound membrane module SWRO 9 through the second high-pressure pump 8 (operating pressure 60 - 65 bar) for purification and concentration treatment to obtain the second-stage permeate (TDS 100 mg / L) and the second-stage concentrate (TDS 70000 mg / L); Discharge the said second-stage permeate externally, and return the said second-stage concentrate to the pretreatment water tank 1.

[0097] Example 2

[0098] This example provides a high-concentration brine concentration and reduction system, as Figure 3 shown, the said system includes a pretreatment unit, a SWRO spiral wound reverse osmosis unit, and a two-stage tubular membrane concentration and reduction unit;

[0099] The pretreatment unit is provided with a pretreatment water tank 1; The pretreatment water tank is connected with a water inlet pipe 2, a water outlet pipe 3, and a return water pipe 4;

[0100] The two-stage tubular membrane concentration and reduction units are connected in series; The first-stage tubular membrane concentration and reduction unit is provided with a first booster pump, a first security filter, a first high-pressure pump, and a tubular membrane module connected in sequence; The second-stage tubular membrane concentration and reduction unit is provided with a first security filter, a first high-pressure pump, and a tubular membrane module connected in sequence; Each stage of the tubular membrane module is provided with a first-stage permeate outlet pipeline and a first-stage concentrate outlet pipeline; The tubular membrane module 15-1 of the first-stage tubular membrane concentration and reduction unit includes 4 tubular membrane columns, and the 4 tubular membrane columns are connected in series; The tubular membrane module 15-2 of the second-stage tubular membrane concentration and reduction unit includes 2 tubular membrane columns, and the 2 tubular membrane columns are connected in series; Each tubular membrane column is provided with a separation membrane element, and the salt permeability of the separation membrane element is 30% - 40%; The first security filter adopts a core filter, and the filtration accuracy is 100 um;

[0101] The SWRO spiral wound reverse osmosis unit is the same as that in Example 1;

[0102] The water outlet pipe 3 is connected to the first booster pump 12-1 of the first-stage tubular membrane concentration and reduction unit;

[0103] The first-stage permeate outlet pipeline 16-1 of the first-stage tubular membrane concentration and reduction unit is connected to the intermediate water tank 5;

[0104] The first-stage concentrate outlet pipeline 17-1 of the first-stage tubular membrane concentration and reduction unit is connected to the inlet of the first security filter 13-2 of the second-stage tubular membrane concentration and reduction unit;

[0105] The first-stage permeate outlet pipeline 16-2 of the second-stage network tube type membrane concentration and reduction unit is connected to the return water pipe 4; the first-stage concentrated liquid outlet pipeline 17-2 of the second-stage network tube type membrane concentration and reduction unit is connected to the evaporation and crystallization system;

[0106] The secondary permeate outlet pipeline 10 is connected to the outside of the system;

[0107] The secondary concentrated liquid outlet pipeline 11 is connected to the return water pipe 4.

[0108] This embodiment also provides a method for concentrating and reducing high-concentration brine. The method uses the above system and includes the following steps:

[0109] Feed the high-concentration brine (TDS 70000mg / L) from the pretreatment water tank into the first security filter 13-1 of the first-stage network tube type membrane concentration and reduction unit through the first booster pump (operating pressure 3-4 bar). The water outlet of the first security filter 13-1 of the first-stage network tube type membrane concentration and reduction unit is fed into the inlet of the network tube type membrane module 15-1 of the first-stage network tube type membrane concentration and reduction unit through the first high-pressure pump (operating pressure 65-70 bar) for concentration treatment, obtaining the first-stage primary permeate (TDS 30000mg / L) and the first-stage primary concentrated liquid (TDS 120000mg / L), with a water recovery rate of 60%-65%;

[0110] Feed the first-stage primary concentrated liquid into the inlet of the network tube type membrane module 15-2 of the second-stage network tube type membrane concentration and reduction unit through the first security filter and the first high-pressure pump (operating pressure 65-70 bar) of the second-stage network tube type membrane concentration and reduction unit for concentration treatment, obtaining the second-stage primary permeate (TDS 70000mg / L) and the second-stage primary concentrated liquid (TDS 160000mg / L), with a water recovery rate of 60%-65%;

[0111] Return the second-stage primary permeate to the pretreatment water tank 1;

[0112] Send the second-stage primary concentrated liquid to the evaporation and crystallization system;

[0113] Feed the first-stage primary permeate into the intermediate water tank 5 and pump it into the second security filter 7 by the second booster pump 6 (operating pressure 3-4 bar); Next, the water outlet of the second security filter 7 enters the inlet of the spiral wound membrane module SWRO9 through the second high-pressure pump 8 (operating pressure 60-65 bar) for purification and concentration treatment, obtaining the secondary permeate (TDS 200mg / L) and the secondary concentrated liquid (TDS 70000mg / L); Discharge the secondary permeate outside and return the secondary concentrated liquid to the pretreatment water tank 1.

[0114] Embodiment 3

[0115] This embodiment provides a high-concentration brine concentration reduction system, as Figure 4 shown. The system includes a pretreatment unit, a SWRO spiral wound reverse osmosis unit, and a three-stage tubular membrane concentration reduction unit;

[0116] The pretreatment unit is provided with a pretreatment water tank; the pretreatment water tank is connected with a water inlet pipe, a water outlet pipe, and a water return pipe;

[0117] The three-stage tubular membrane concentration reduction units are connected in series; the first-stage tubular membrane concentration reduction unit is provided with a first booster pump, a first security filter, a first high-pressure pump, and a tubular membrane module connected in sequence; the second-stage tubular membrane concentration reduction unit and the third-stage tubular membrane concentration reduction unit are both provided with a first security filter, a first high-pressure pump, and a tubular membrane module connected in sequence; each stage of the tubular membrane module is provided with a primary permeate outlet pipeline and a primary concentrate outlet pipeline; the tubular membrane module 15-1 of the first-stage tubular membrane concentration reduction unit includes 3 tubular membrane columns, and the 3 tubular membrane columns are connected in series; the tubular membrane module 15-2 of the second-stage tubular membrane concentration reduction unit includes 2 tubular membrane columns, and the 2 tubular membrane columns are connected in series; the tubular membrane module 15-3 of the third-stage tubular membrane concentration reduction unit includes 1 tubular membrane column; each tubular membrane column is provided with a separation membrane element, and the salt rejection rate of the separation membrane element is 30%-40%; the first security filter uses a core filter with a filtration accuracy of 100um;

[0118] The SWRO spiral wound reverse osmosis unit is provided with an intermediate water tank 5, a second booster pump 6, a second security filter 7, a second high-pressure pump 8, and a spiral wound membrane module SWRO9 connected in sequence; the spiral wound membrane module SWRO9 is provided with a secondary permeate outlet pipeline 10 and a secondary concentrate outlet pipeline 11; the spiral wound membrane module SWRO9 includes 2 spiral wound reverse osmosis membrane columns, and the 2 spiral wound reverse osmosis membrane columns are connected in series; the second security filter 7 uses a core filter with a filtration accuracy of 50um;

[0119] The water outlet pipe 3 is connected to the first booster pump 12-1 of the first-stage tubular membrane concentration reduction unit;

[0120] The primary permeate outlet pipeline 16-1 of the first-stage tubular membrane concentration reduction unit is connected to the intermediate water tank 5;

[0121] The primary concentrate outlet pipeline 17-1 of the first-stage tubular membrane concentration reduction unit is connected to the inlet of the first security filter 13-2 of the second-stage tubular membrane concentration reduction unit;

[0122] The first-stage permeate outlet pipeline 16-2 of the second-stage network tube type membrane concentration and reduction unit is connected to the return water pipe 4; the first-stage concentrated liquid outlet pipeline 17-2 of the second-stage network tube type membrane concentration and reduction unit is connected to the inlet of the first security filter 13-3 of the third-stage network tube type membrane concentration and reduction unit;

[0123] The first-stage permeate outlet pipeline 16-3 of the third-stage network tube type membrane concentration and reduction unit is connected to the inlet of the first security filter 13-2 of the second-stage network tube type membrane concentration and reduction unit; the first-stage concentrated liquid outlet pipeline 17-3 of the third-stage network tube type membrane concentration and reduction unit is connected to the evaporation and crystallization system;

[0124] The secondary permeate outlet pipeline 10 is connected to outside the system;

[0125] The secondary concentrated liquid outlet pipeline 11 is connected to the return water pipe 4.

[0126] This embodiment also provides a method for concentrating and reducing high-concentration brine. The method uses the above system and includes the following steps:

[0127] The high-concentration brine (TDS 70000mg / L) is sent from the pretreatment water tank 1 through the first booster pump (operating pressure 3-4 bar) to the first security filter 13-1 of the first-stage network tube type membrane concentration and reduction unit for treatment. The water outlet of the first security filter 13-1 of the first-stage network tube type membrane concentration and reduction unit is sent through the first high-pressure pump (operating pressure 65-70 bar) to the inlet of the network tube type membrane module 15-1 of the first-stage network tube type membrane concentration and reduction unit for concentration treatment, obtaining first-stage primary permeate (TDS 30000mg / L) and first-stage primary concentrated liquid (TDS 120000mg / L), with a water recovery rate of 60%-65%;

[0128] The first-stage primary concentrated liquid enters the inlet of the network tube type membrane module 15-2 of the second-stage network tube type membrane concentration and reduction unit through the first security filter and the first high-pressure pump (operating pressure 65-70 bar) of the second-stage network tube type membrane concentration and reduction unit for concentration treatment, obtaining second-stage primary permeate (TDS 70000mg / L) and second-stage primary concentrated liquid (TDS 160000mg / L), with a water recovery rate of 60%-65%;

[0129] The second-stage primary permeate is refluxed to the pretreatment water tank 1;

[0130] The two-stage primary concentrated liquid is concentrated through the first security filter and the first high-pressure pump (operating pressure 65 - 70 bar) of the third-stage network tubular membrane concentration and reduction unit and enters the inlet of the network tubular membrane module 15-3 of the third-stage network tubular membrane concentration and reduction unit to obtain the third-stage primary permeate (TDS 120,000 mg / L) and the third-stage primary concentrated liquid (TDS 200,000 mg / L), with a water recovery rate of 60% - 65%;

[0131] The third-stage primary permeate is sent to the inlet of the first security filter 13-2 of the second-stage network tubular membrane concentration and reduction unit;

[0132] The third-stage primary concentrated liquid is sent to the evaporation crystallization system;

[0133] The first-stage primary permeate is sent into the intermediate water tank 5 and pumped into the second security filter 7 by the second booster pump 6 (operating pressure 3 - 4 bar); next, the water outlet of the second security filter 7 enters the inlet of the spiral wound membrane module SWRO9 through the second high-pressure pump 8 (operating pressure 60 - 65 bar) for purification and concentration treatment to obtain the secondary permeate (TDS 200 mg / L) and the secondary concentrated liquid (TDS 70,000 mg / L); the secondary permeate is discharged, and the secondary concentrated liquid is refluxed to the pretreatment water tank 1.

[0134] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for concentrating and reducing high-concentration brine, characterized in that: The system used in the method includes a pretreatment unit, a SWRO spiral reverse osmosis unit and at least one section of a mesh-tube membrane concentration and reduction unit; The pretreatment unit is provided with a pretreatment water tank; the pretreatment water tank is connected with a water inlet pipe, a water outlet pipe and a water return pipe; When the system is provided with multiple sections of network-managed membrane concentration and reduction units, each section of the network-managed membrane concentration and reduction units is connected in series in sequence; each section of the network-managed membrane concentration and reduction unit is provided with a network-managed membrane assembly, and the network-managed membrane assembly is provided with a primary permeate outlet pipeline and a primary concentrated liquid outlet pipeline; The net-tube membrane assembly comprises at least one net-tube membrane column. When the net-tube membrane assembly comprises multiple net-tube membrane columns, the multiple net-tube membrane columns are connected in series. Each net-tube membrane column is provided with a separation membrane element, and the salt permeability of the separation membrane element is 30%-40%. The SWRO spiral reverse osmosis unit is provided with a spiral membrane assembly SWRO; the spiral membrane assembly SWRO is provided with a secondary permeate outlet pipeline and a secondary concentrate outlet pipeline; The outlet pipe is connected to the first section of the mesh-type membrane concentration and reduction unit; The primary permeate outlet pipeline of the first section of the network-tube membrane concentration and reduction unit is connected to the SWRO spiral reverse osmosis unit; The primary concentrated liquid outlet pipeline of the first-stage mesh-tube membrane concentration and reduction unit is connected to the evaporation crystallization system, or connected to the second-stage mesh-tube membrane concentration and reduction unit; The secondary permeate outlet pipeline is connected to the outside of the system; The secondary concentrated liquid outlet pipeline is connected to the water return pipe; The method comprises the following steps: The highly concentrated brine is sent from the pretreatment water tank to the first section of the network-tube membrane concentration and reduction unit for treatment to obtain a section of primary permeate and a section of primary concentrate; The first-stage concentrated liquid is sent to an evaporation crystallization system, or to a second-stage mesh-type membrane concentration and reduction unit; The first stage permeate is sent to the SWRO spiral reverse osmosis unit for treatment to obtain a second stage permeate and a second stage concentrate; Discharging the secondary permeate and returning the secondary concentrated liquid to the pretreatment water tank; The TDS of the highly concentrated brine is 61000-75000 mg / L; The TDS of the secondary permeate is 90-250 mg / L; The TDS of the first-stage concentrated liquid is 115000-145000 mg / L; The working pressure of each section of the network tube membrane concentration and reduction unit is 3.5-7.0MPa; The water recovery rate of each section of the network-tube membrane concentration and reduction unit is 60%-65%; The working pressure of the SWRO spiral reverse osmosis unit is 3.5-6.5 MPa; The water recovery rate of the SWRO spiral reverse osmosis unit is 70%-80%.

2. The method for concentrating and reducing high-concentration brine according to claim 1, characterized in that: Each section of the network-managed membrane concentration and reduction unit is provided with a first safety filter, a first high-pressure pump and the network-managed membrane assembly connected in sequence; The first section of the network-managed membrane concentration and reduction unit is also provided with a first booster pump, and the outlet pipe is connected to the first booster pump and the first safety filter of the first section of the network-managed membrane concentration and reduction unit in sequence; The SWRO rolled reverse osmosis unit is provided with an intermediate water tank, a second booster pump, a second safety filter and a second high-pressure pump connected in sequence; the rolled membrane assembly SWRO is provided with a SWRO water inlet; the primary permeate outlet pipeline of the first section of the network-pipe membrane concentration and reduction unit is connected to the intermediate water tank; the second high-pressure pump is connected to the SWRO water inlet.

3. The method for concentrating and reducing high-concentration brine according to claim 2, characterized in that: The first security filter is a core filter and / or a precision filter; the filtering accuracy of the first security filter is 10-100μm.

4. The method for concentrating and reducing high-concentration brine according to claim 2, characterized in that: The second security filter is a core filter or a precision filter; the filtering accuracy of the second security filter is 5-50μm.

5. The method for concentrating and reducing high-concentration brine according to claim 2, characterized in that: When the system is provided with two sections of network-managed membrane concentration and reduction units, the primary concentrated liquid outlet pipeline of the first section of the network-managed membrane concentration and reduction unit is connected to the inlet of the first security filter of the second section of the network-managed membrane concentration and reduction unit; The primary permeate outlet pipeline of the second section of the network-managed membrane concentration and reduction unit is connected to the return pipe; the primary concentrated liquid outlet pipeline of the second section of the network-managed membrane concentration and reduction unit is connected to the evaporation crystallization system.

6. The method for concentrating and reducing high-concentration brine according to claim 2, characterized in that: When the system is provided with three sections of network-managed membrane concentration and reduction units, the primary concentrated liquid outlet pipeline of the first section of the network-managed membrane concentration and reduction unit is connected to the inlet of the first security filter of the second section of the network-managed membrane concentration and reduction unit; The primary permeate outlet pipeline of the second section of the network-managed membrane concentration and reduction unit is connected to the return pipe; the primary concentrate outlet pipeline of the second section of the network-managed membrane concentration and reduction unit is connected to the inlet of the first security filter of the third section of the network-managed membrane concentration and reduction unit; The primary permeate outlet pipeline of the third section network-managed membrane concentration and reduction unit is connected to the inlet of the first safety filter of the second section network-managed membrane concentration and reduction unit; the primary concentrated liquid outlet pipeline of the third section network-managed membrane concentration and reduction unit is connected to the evaporation crystallization system.

7. The method for concentrating and reducing high-concentration brine according to claim 1, characterized in that: The first concentrated liquid outlet pipeline is provided with a first concentrated liquid flow regulating valve.

8. The method for concentrating and reducing high-concentration brine according to claim 7, characterized in that: The net-tube membrane assembly comprises 1 to 8 net-tube membrane columns.

9. The method for concentrating and reducing high-concentration brine according to claim 1, characterized in that: The secondary concentrated liquid outlet pipeline is provided with a second concentrated water flow regulating valve; The spiral wound membrane assembly SWRO includes at least one spiral wound reverse osmosis membrane column; when the spiral wound membrane assembly SWRO includes multiple spiral wound reverse osmosis membrane columns, the multiple spiral wound reverse osmosis membrane columns are connected in series.

10. The method for concentrating and reducing highly concentrated brine according to claim 9, characterized in that: The spiral wound membrane assembly SWRO comprises 1 to 6 spiral wound reverse osmosis membrane columns.

11. The method for concentrating and reducing highly concentrated brine according to claim 1, characterized in that: The first stage concentrated liquid is sent to the second stage net-managed membrane concentration and reduction unit, and is processed by the second stage net-managed membrane concentration and reduction unit to obtain the second stage first stage permeate and the second stage first stage concentrated liquid; Returning the second-stage primary permeate to the pretreatment water tank; The second-stage primary concentrated liquid is sent to an evaporation crystallization system; The TDS of the second-stage first-stage concentrated liquid is 155,000-165,000 mg / L.

12. The method for concentrating and reducing highly concentrated brine according to claim 1, characterized in that: The first stage concentrated liquid is sent to the second stage net-managed membrane concentration and reduction unit, and is processed by the second stage net-managed membrane concentration and reduction unit to obtain the second stage first stage permeate and the second stage first stage concentrated liquid; Returning the second-stage primary permeate to the pretreatment water tank; The second-stage primary concentrated liquid is sent to the third-stage net-managed membrane concentration and reduction unit, and is processed by the third-stage net-managed membrane concentration and reduction unit to obtain a third-stage primary permeate and a third-stage primary concentrated liquid; The first-stage permeate of the three sections is sent to the inlet of the first security filter of the second-stage mesh-type membrane concentration and reduction unit; The three-stage primary concentrated liquid is sent to an evaporation crystallization system; The TDS of the three-stage primary concentrated liquid is 190,000-210,000 mg / L.

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