A centrifugal mother liquor deep treatment secondary reverse osmosis concentrated water collecting and recycling device

Abstract

This utility model relates to the field of chemical production technology, specifically a device for collecting and reusing concentrated water from a two-stage reverse osmosis process for deep treatment of centrifugal mother liquor. It includes a two-stage reverse osmosis unit, a concentrated water collection tank connected to the concentrated water outlet of the two-stage reverse osmosis unit via a concentrated water outlet pipe, and a circulating water tank connected to the concentrated water collection tank outlet via a concentrated water delivery pipe. The device further includes a circulation pipe connected to the concentrated water delivery pipe and a backwashing purification system mounted on the circulation pipe. The two-stage reverse osmosis unit is also connected to a two-stage reverse osmosis inlet pipe and a two-stage reverse osmosis outlet pipe. The end of the circulation pipe is connected to the two-stage reverse osmosis outlet pipe, and a recovery pipe is connected to the two-stage reverse osmosis inlet pipe. The end of the recovery pipe is connected in parallel to the concentrated water delivery pipe and is located on the side of the circulation pipe near the concentrated water collection tank. This utility model achieves refined protection of the reverse osmosis membrane through a backwashing purification system composed of an ozone generator, a pH adjustment tank, and a precision filter.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, specifically to a device for collecting and reusing concentrated water from a two-stage reverse osmosis process for deep treatment of centrifugal mother liquor. Background Technology

[0002] In chemical production (especially in the polyvinyl chloride industry), centrifugal mother liquor, as a core wastewater generated during the production process, requires advanced treatment and reuse, which has become a crucial step for enterprises to achieve water resource recycling and reach the environmental protection goal of "zero" emissions. Currently, the industry generally adopts a combined process of "ultrafiltration pretreatment + two-stage reverse osmosis advanced treatment" to treat centrifugal mother liquor: the ultrafiltration unit is responsible for removing suspended solids, colloids, and some microorganisms from the mother liquor, providing water quality assurance for subsequent advanced treatment; the two-stage reverse osmosis equipment, with its high-precision separation characteristics, achieves the core functions of desalination and removal of small molecule recalcitrant organic matter, ultimately producing desalinated water that meets production requirements.

[0003] To address the technical challenges of ultrafiltration processes, existing technologies have proposed targeted solutions. For example, Chinese patent CN221217510U discloses a dual-purpose device for collecting concentrated water and chemical cleaning in a centrifugal mother liquor ultrafiltration unit. This device, through the coordinated operation of a chemical cleaning tank, a dual-purpose cleaning and discharge pump, and a biochemical reaction treatment tank, transports the low-salt concentrated water generated by the ultrafiltration unit to a biochemical system for further deep treatment, avoiding water waste. It also utilizes acid and alkali agents to chemically clean the fouled ultrafiltration membrane, effectively restoring its filtration performance and improving the operational stability of the ultrafiltration process. However, due to fundamental differences in the treatment object (intermediate water after ultrafiltration) and the characteristics of core equipment (reverse osmosis membrane precision and corrosion resistance) between the secondary reverse osmosis process and the ultrafiltration process, existing technologies (including the solution in CN221217510U) still have unresolved technical problems in the secondary reverse osmosis process. 1. Lack of adaptability for secondary reverse osmosis concentrate reuse: The concentrate produced after separation in the secondary reverse osmosis unit has the characteristics of high salinity and contains small-molecule, recalcitrant organic matter, which differs significantly in quality from ultrafiltration concentrate (low salinity, mainly composed of physical impurities). The biological reaction treatment tank used in CN221217510U relies on microbial activity to purify water, but the high-salt environment will cause the biological bacteria to become inactive, making it unsuitable for the treatment requirements of secondary reverse osmosis concentrate. Directly discharging this concentrate not only wastes water resources but also violates the environmental protection requirement of zero discharge. It is urgent to build a recycling, storage, and reuse path suitable for high-salt concentrate.

[0004] 2. Insufficient backwash protection for secondary reverse osmosis membranes: Secondary reverse osmosis membranes mostly use polyamide composite membranes, which have high separation accuracy (capable of retaining small molecule salts) but poor corrosion resistance, requiring strict control over the purity, pH value, and suspended solids content of the backwash water. The direct acid-base cleaning solution in CN221217510U is only suitable for ultrafiltration membranes with strong acid and alkali resistance. Direct application to secondary reverse osmosis membranes can lead to oxidative degradation or structural damage to the membrane elements. Furthermore, existing backwash processes lack pretreatment of the backwash water. Without methods for oxidizing and decomposing organic matter, or precise pH adjustment and fine filtration, contaminants in the backwash water can easily exacerbate reverse osmosis membrane clogging, significantly shortening the membrane element's lifespan.

[0005] 3. Insufficient System Operation and Control Precision: The two-stage reverse osmosis process has extremely high requirements for the stability of concentrate delivery flow rate and collection tank level. Fluctuations in flow rate or abnormal levels will directly lead to a decrease in desalination efficiency. In existing technologies, concentrate collection relies solely on a single level gauge for monitoring, lacking means to assess the accumulation of impurities in the collection tank (such as differential pressure monitoring), making it prone to pipeline blockage due to impurity deposition; furthermore, the lack of precise flow metering devices makes it impossible to achieve stable control of concentrate delivery. In addition, backwash water is mostly discharged directly after a single use, without forming a closed-loop recycling system, further increasing water consumption and operating costs.

[0006] In summary, existing technologies (including the solution for ultrafiltration processes in CN221217510U) cannot provide effective solutions to the aforementioned technical challenges in the secondary reverse osmosis process. Therefore, there is an urgent need to develop an integrated device that can adapt to the characteristics of secondary reverse osmosis concentrate, achieve efficient concentrate recovery and reuse, and simultaneously possess precise backwashing protection for membrane elements and stable system control functions. This would fill the technological gap and improve the overall economic efficiency and environmental friendliness of deep treatment of centrifugal mother liquor. Utility Model Content

[0007] The purpose of this invention is to provide a device for collecting and reusing concentrated water from secondary reverse osmosis after deep treatment of centrifugal mother liquor, in order to solve the problems mentioned in the prior art in the background.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a device for collecting and reusing concentrated water from a two-stage reverse osmosis process for deep treatment of centrifugal mother liquor, comprising a two-stage reverse osmosis device, a concentrated water collection tank whose inlet is connected to the concentrated water outlet of the two-stage reverse osmosis device via a concentrated water outlet pipe, and a circulating water tank whose inlet is connected to the outlet of the concentrated water collection tank via a concentrated water delivery pipe. The device further comprises a circulating pipe connected to the concentrated water delivery pipe and a backwashing purification system mounted on the circulating pipe. The two-stage reverse osmosis device is also connected to a two-stage reverse osmosis inlet pipe and a two-stage reverse osmosis outlet pipe. The end of the circulating pipe is connected to the two-stage reverse osmosis outlet pipe. A recovery pipe is connected to the two-stage reverse osmosis inlet pipe, and the end of the recovery pipe is connected in parallel to the concentrated water delivery pipe and located on the side of the circulating pipe near the concentrated water collection tank.

[0009] Furthermore, the backwashing purification system includes an ozone generator, a pH adjustment tank, and a precision filter connected in series on the circulation pipe.

[0010] Furthermore, a concentrated water delivery pump is connected in series with the concentrated water delivery pipe, which is located near the circulating water tank.

[0011] Furthermore, a circulation pump is connected in series with the circulation pipe, which is close to the secondary reverse osmosis outlet pipe.

[0012] Furthermore, the bottom of the concentrate collection tank is equipped with a drain pipe.

[0013] Furthermore, the concentrate collection tank is equipped with a differential pressure level gauge and a float level gauge.

[0014] Furthermore, the concentrate delivery pipe is equipped with a concentrate flow meter located between the circulating water tank and the concentrate delivery pump.

[0015] Furthermore, regulating valves are provided on the concentrate outlet pipe, concentrate delivery pipe, circulation pipe, secondary reverse osmosis inlet pipe, secondary reverse osmosis outlet pipe, recovery pipe, and drain pipe.

[0016] The specific beneficial effects of this utility model are as follows: 1. Adapts to the characteristics of high-salt concentrate from secondary reverse osmosis, enabling efficient concentrate recovery and reuse. Addressing the issue in the background technology that the high-salt nature of secondary reverse osmosis concentrate prevents its reuse through biochemical treatment, this invention constructs a recycling system adapted for high-salt concentrate through the coordinated design of a circulating water tank, a concentrate transfer pump, and a recovery pipe. The circulating water tank directly stores the high-salt concentrate produced by secondary reverse osmosis, avoiding the problem of microbial inactivation caused by high salt in traditional biochemical reaction tanks. Simultaneously, the recovery pipe returns the backwashed wastewater to the concentrate transfer pipe, ultimately flowing back into the circulating water tank to achieve closed-loop reuse. This not only eliminates water waste caused by direct discharge of concentrate but also meets the zero-emission environmental protection requirements of chemical production. Practical application verification shows that this design can increase the water recovery rate of deep treatment of centrifugal mother liquor by 15%-20%, reducing the fresh water consumption cost for enterprises.

[0017] 2. Protects the secondary reverse osmosis membrane elements and significantly extends membrane lifespan. To address the problems of direct acid and alkali cleaning damaging reverse osmosis membranes and the exacerbation of membrane fouling due to the lack of pretreatment of backwash water in existing technologies, this invention utilizes a backwash purification system composed of an ozone generator, a pH adjustment tank, and a precision filter to achieve refined protection of the reverse osmosis membrane. The ozone generator efficiently oxidizes and decomposes small-molecule, recalcitrant organic matter in the backwash water, preventing irreversible fouling caused by organic matter adhering to the membrane surface. The pH adjustment tank, through an automatic dosing device, precisely controls the pH value of the backwash water within a safe range of 6.5-8.5, eliminating structural damage to the polyamide composite membrane caused by acid and alkali corrosion. The precision filter (5μm filtration accuracy) traps suspended solids and particulate matter in the backwash water, preventing membrane pore blockage. Furthermore, the backwash water enters the equipment in reverse from the secondary reverse osmosis outlet pipe, forming a gentle backwash flow channel and avoiding physical damage to the membrane elements from high-pressure impacts. This design can extend the service life of the secondary reverse osmosis membrane by 30%-50%, reduce the frequency of membrane element replacement, and lower equipment operation and maintenance costs.

[0018] 3. Improve system stability and reduce operating and energy costs. To address the operational instability issues caused by the single level monitoring method, lack of flow metering, and backwash water discharge in the background technology, this utility model optimizes system operating accuracy through a dual level gauge, concentrate flow meter, and closed-loop control design: the differential pressure level gauge monitors the level difference within the concentrate collection tank, promptly assessing impurity accumulation and preventing pipeline blockage; the float level gauge provides real-time feedback on the liquid level, offering precise signals for starting and stopping the concentrate delivery pump and preventing pump damage from dry running; and the concentrate flow meter measures the delivery flow rate in real-time, precisely controlling the flow rate to stabilize it at 5-8 m³ / h via a regulating valve. 3 The system operates at a rate of [ / h], ensuring stable secondary reverse osmosis desalination efficiency. Simultaneously, the closed-loop circulation of backwash water, constructed through the circulation and recovery pipes, prevents the discharge of backwash water after a single use, reducing water consumption and lowering additional energy consumption for wastewater treatment. This design extends the system's continuous operating cycle from the traditional 72 hours to 168 hours (1 week), reducing unplanned downtime and improving production efficiency.

[0019] 4. High structural integration and strong adaptability, filling a gap in existing technologies. This invention integrates concentrate collection, membrane backwashing purification, and operation control functions into one unit, eliminating the need for additional complex equipment, reducing footprint, and allowing direct connection to existing "ultrafiltration and secondary reverse osmosis" centrifugal mother liquor treatment processes. Compared to CN221217510U, a dedicated device for ultrafiltration processes, this solution fills the technical gap in concentrate recovery and membrane protection in the secondary reverse osmosis process through targeted design (such as abandoning biochemical treatment and adding a backwashing purification unit). It not only meets the centrifugal mother liquor treatment needs of the polyvinyl chloride industry but is also adaptable to secondary reverse osmosis concentrate treatment scenarios in other chemical fields, demonstrating wide applicability and significant promotional value. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the present invention.

[0021] In the diagram: 1. Secondary reverse osmosis unit; 2. Concentrate outlet pipe; 3. Concentrate collection tank; 4. Concentrate delivery pipe; 5. Circulating water tank; 6. Circulation pipe; 7. Secondary reverse osmosis inlet pipe; 8. Secondary reverse osmosis outlet pipe; 9. Recovery pipe; 10. Ozone generator; 11. pH adjustment tank; 12. Precision filter; 13. Concentrate delivery pump; 14. Circulation pump; 15. Drain pipe; 16. Differential pressure level gauge; 17. Float level gauge; 18. Concentrate flow meter; 19. Control valve. Detailed Implementation

[0022] The following is in conjunction with the appendix Figure 1 This document provides a detailed description of the specific implementation method of a two-stage reverse osmosis concentrate collection and reuse device for deep treatment of centrifugal mother liquor according to the present invention. This embodiment is only used to explain the present invention and is not intended to limit the scope of protection of the present invention.

[0023] like Figure 1 As shown, the centrifugal mother liquor deep treatment secondary reverse osmosis concentrate collection and reuse device in this embodiment mainly consists of a secondary reverse osmosis core treatment unit, a concentrate collection and storage unit, a backwashing purification circulation unit, and an auxiliary monitoring and control unit. It can realize three major functions: normal secondary reverse osmosis treatment, efficient concentrate collection and reuse, and equipment backwashing and maintenance. This solves the problems of concentrate waste, easy clogging and scaling of secondary reverse osmosis equipment, and poor operational stability in existing processes, improving water resource utilization in chemical production and reducing equipment maintenance costs. The following provides a detailed description of each component and the overall working process: The secondary reverse osmosis core treatment unit consists of a secondary reverse osmosis device 1, a secondary reverse osmosis inlet pipe 7, and a secondary reverse osmosis outlet pipe 8. Among them: The secondary reverse osmosis unit 1 is made of 304 stainless steel, model BW30-4040, with a polyamide composite membrane as the core membrane element, and a designed processing capacity of 5m³. 3 With a capacity of / h and a pressure rating of 1.6MPa, it is used for deep treatment of incoming centrifugal mother liquor, achieving efficient separation of pure water and concentrated water.

[0024] The secondary reverse osmosis inlet pipe 7 is made of 304 stainless steel with a diameter of DN65. One end is connected to the external centrifugal mother liquor delivery pipeline, and the other end is connected to the inlet of the secondary reverse osmosis unit 1 for conveying the centrifugal mother liquor to be treated. The secondary reverse osmosis outlet pipe 8 is made of 304 stainless steel with a diameter of DN50. One end is connected to the pure water outlet of the secondary reverse osmosis unit 1, and the other end is connected to the external pure water recovery pipeline. It is also connected to the end of the circulation pipe 6 for discharging treated pure water or connecting backwash water.

[0025] The concentrate collection and storage unit includes a concentrate collection tank 3, a concentrate outlet pipe 2, a concentrate delivery pipe 4, a circulating water tank 5, an empty pipe 15, and a concentrate delivery pump 13. Among them: Concentrate collection tank 3 is made of PP material, with a size of Φ1500×2000 and an effective volume of 3m³. 3 The first pipe, with a wall thickness of 12mm, is used for temporary storage of the concentrate discharged from the second-stage reverse osmosis unit 1, preventing waste caused by direct discharge of concentrate. The second concentrate outlet pipe, made of 304 stainless steel with a diameter of DN50, connects to the concentrate outlet of the second-stage reverse osmosis unit 1 at one end and to the inlet of the concentrate collection tank 3 at the other end, used to transport the separated concentrate. The third concentrate delivery pipe, also made of 304 stainless steel with a diameter of DN65, connects to the outlet of the concentrate collection tank 3 at one end and extends to the circulating water tank 5 at the other end, used to transport the concentrate from the concentrate collection tank 3 to the circulating water tank 5 for storage and reuse.

[0026] Circulating water tank 5 is constructed of reinforced concrete with an epoxy resin anti-corrosion coating on the inside, and has an effective volume of 50m³. 3 The tank, measuring 4m × 3m × 4m, is used for long-term storage of recycled concentrate for reuse in subsequent production processes. The drain pipe 15, made of 304 stainless steel with a diameter of DN40, is located at the bottom of the concentrate collection tank 3 and is used to periodically drain impurities and residual liquid deposited in the tank, preventing impurity accumulation.

[0027] Concentrate transfer pump 13 is made of fluoroplastic alloy, model IHF50-32-125, with a rated flow rate of 10m³ / h. 3 The pump has a head of 32m and a rated power of 4kW. It is connected in series in the concentrate delivery pipe 4 near the circulating water tank 5 to provide power for the delivery of concentrate from the concentrate collection tank 3 to the circulating water tank 5.

[0028] The backwashing and purification circulation unit includes a circulation pipe 6, a backwashing and purification system, a circulation pump 14, and a recovery pipe 9. Among these, The circulation pipe 6 is made of 304 stainless steel with a diameter of DN50. One end is connected to the concentrate delivery pipe 4 (located on the side of the circulation pipe 6 near the concentrate collection tank 3), and the other end is connected to the secondary reverse osmosis outlet pipe 8 to construct the backwash water circulation channel.

[0029] The backwash purification system consists of an ozone generator 10, a pH adjustment tank 11, and a precision filter 12, connected in series on the circulation pipe 6. It is used to purify the backwash concentrate, preventing impurities and harmful substances from damaging the membrane elements of the secondary reverse osmosis unit 1. The ozone generator 10 is made of stainless steel, model CF-G-10, with an ozone output of 10 g / h and an operating pressure of 0.4 MPa. It is used to oxidize and decompose organic matter, microorganisms, and other pollutants in the concentrate. The pH adjustment tank 11 is made of PP, model Φ800×1200, with an effective volume of 0.5 m³. 3 Equipped with an automatic dosing device (model: JY-100), it adjusts the pH of the backwash water to a suitable range of 6.5-8.5 to reduce corrosion of the reverse osmosis membrane. The precision filter 12 is made of 304 stainless steel, model SF-50-5μ, with a filtration accuracy of 5μm and a polypropylene filter element. It filters suspended solids, particulate matter, and other impurities from the backwash water, protecting the reverse osmosis membrane from clogging. The circulation pump 14 is made of fluoroplastic alloy, model IHF40-25-160, with a rated flow rate of 5m³ / h. 3 The pump has a flow rate of 100 m / h, a head of 40 m, and a rated power of 3 kW. It is connected in series in the circulation pipe 6 near the secondary reverse osmosis outlet pipe 8 to provide power for the circulation of backwash water. The recovery pipe 9 is made of 304 stainless steel with a diameter of DN50. One end is connected to the secondary reverse osmosis inlet pipe 7, and the other end is connected in parallel to the concentrate delivery pipe 4 (located on the side of the circulation pipe 6 near the circulation pool 5). It is used to return the backwash wastewater to the circulation pool 5 to realize the recycling of backwash water.

[0030] The auxiliary monitoring and control unit includes a differential pressure level gauge 16, a float level gauge 17, a concentrate flow meter 18, and a regulating valve 19. Among them: Differential pressure level gauge 16, model UQZ-200, has a measuring range of 0-2m and an accuracy of ±1%FS. It is installed on the side of the concentrate collection tank 3 to monitor the liquid level difference within the tank and determine if impurities are accumulating. Float level gauge 17, model UQK-02, has a measuring range of 0-2m and an output signal of 4-20mA. It is installed on the top of the concentrate collection tank 3 to monitor the liquid level in real time, providing a signal for starting and stopping the concentrate transfer pump 13. Concentrate flow meter 18, model LZB-50, has a measuring range of 2-20m. 3 / h, with an accuracy of ±2.5%FS, is installed on the concentrate delivery pipe 4 (located between the circulating water tank 5 and the concentrate delivery pump 13) to measure the flow rate of concentrate delivery, facilitating flow control during the production process.

[0031] The regulating valve 19, model ZJHP-16C, is made of cast steel, with a nominal diameter of DN40-DN65 and a pressure rating of 1.6MPa. It is installed on the concentrate outlet pipe 2, concentrate delivery pipe 4, circulation pipe 6, secondary reverse osmosis inlet pipe 7, secondary reverse osmosis outlet pipe 8, recovery pipe 9, and drain pipe 15 to control the on / off state of each pipeline and the flow rate of the medium. It can be adjusted manually or electrically according to the working conditions (electric model ZAZP-16C).

[0032] The connection relationship and specific working process of this utility model are as follows: I. Connection Relationship The components are connected sequentially via pipelines to form a complete system. The specific connection relationships are as follows: 1. The inlet of the secondary reverse osmosis unit 1 is connected to the secondary reverse osmosis inlet pipe 7, the pure water outlet is connected to the secondary reverse osmosis outlet pipe 8, and the concentrate outlet is connected to the concentrate outlet pipe 2.

[0033] 2. The end of the concentrate outlet pipe 2 away from the secondary reverse osmosis equipment 1 is connected to the inlet of the concentrate collection tank 3, the outlet of the concentrate collection tank 3 is connected to one end of the concentrate delivery pipe 4, and the other end of the concentrate delivery pipe 4 is connected to the inlet of the circulating water tank 5.

[0034] 3. One end of the circulation pipe 6 is connected to the concentrate delivery pipe 4, and the other end is connected to the secondary reverse osmosis outlet pipe 8. The ozone generator 10, pH adjustment tank 11, precision filter 12, and circulation pump 14 are connected in series on the circulation pipe 6.

[0035] 4. One end of the recovery pipe 9 is connected to the secondary reverse osmosis inlet pipe 7, and the other end is connected in parallel to the concentrate delivery pipe 4 (the section of pipe located between the circulation pipe 6 and the circulation pool 5).

[0036] 5. The concentrate delivery pump 13 is connected in series in the section of the concentrate delivery pipe 4 near the circulating water tank 5, and the concentrate flow meter 18 is installed on the concentrate delivery pipe 4 between the concentrate delivery pump 13 and the circulating water tank 5.

[0037] 6. The differential pressure level gauge 16 and the float level gauge 17 are respectively installed on the side and top of the concentrate collection tank 3, and the drain pipe 15 is installed at the bottom of the concentrate collection tank 3. Each pipeline is equipped with a corresponding regulating valve 19.

[0038] In this invention, all component connections adopt mature standard connection methods in the chemical industry to ensure system sealing, pressure resistance, and operational stability. Specifically, pipes with a diameter ≥ DN50 and equipment interfaces with a pressure ≥ 1.0 MPa (such as the connection between the secondary reverse osmosis unit and the concentrate outlet pipe, and the concentrate delivery pipe and the circulating water tank) use GB / T 9119-2010 standard flange connections, with raised face (RF) sealing surfaces and matching acid and alkali resistant rubber gaskets to ensure no leakage under high pressure conditions. Pipes with a diameter < DN50 (such as drain pipes and recovery pipes) and interfaces requiring frequent disassembly and maintenance (such as the inlet and outlet of precision filters, and the dosing port of the pH adjustment tank) use GB / T 7306.1-2000 tapered pipe thread connections, with matching PTFE tape to enhance sealing performance. Interfaces integrally formed with the equipment body (such as the connection between the secondary reverse osmosis inlet pipe and the equipment shell) are welded using argon arc welding, with welding standards conforming to GB / T985.1-2008. A pressure test is performed after welding (the test pressure is 1.5 times the design pressure). (Multiple times), ensuring that the weld is free of defects such as porosity and cracks; all connection parts are selected with corresponding corrosion-resistant seals according to the characteristics of the medium (including high salt and corrosive components) to meet the working conditions of deep treatment of centrifugal mother liquor.

[0039] II. Work Process (a) Normal two-stage reverse osmosis process 1. Open the regulating valve 19 on the secondary reverse osmosis inlet pipe 7 and the secondary reverse osmosis outlet pipe 8, and close the regulating valve 19 on the circulation pipe 6 and the recovery pipe 9. Ensure that the regulating valve 19 on the concentrate delivery pipe 4 leading to the circulation water tank 5 is in the closed state (at this time, the concentrate is temporarily stored in the concentrate collection tank 3).

[0040] 2. The external centrifuged mother liquor enters the secondary reverse osmosis equipment 1 through the secondary reverse osmosis inlet pipe 7. Through the separation effect of the polyamide composite membrane inside the equipment, pure water is discharged from the secondary reverse osmosis outlet pipe 8 to the external pure water recovery system, while concentrated water is discharged from the concentrated water outlet.

[0041] (ii) Concentrate collection process 1. The concentrate produced by the secondary reverse osmosis unit 1 enters the concentrate collection tank 3 through the regulating valve 19 on the concentrate outlet pipe 2 (the transport is achieved by its own pressure; if the pressure is insufficient, a pump can be added to provide power). The float level gauge 17 monitors the liquid level in the tank in real time, and the differential pressure level gauge 16 monitors the liquid level difference to determine whether there is impurity accumulation.

[0042] 2. When the liquid level in the concentrate collection tank 3 reaches the set upper limit (e.g., 1.5m), start the concentrate delivery pump 13 and open the regulating valve 19 on the concentrate delivery pipe 4 leading to the circulating water tank 5. Under the power of the concentrate delivery pump 13, the concentrate is delivered to the circulating water tank 5 for storage through the concentrate delivery pipe 4.

[0043] 3. The concentrate flow meter 18 measures the concentrate delivery flow rate in real time. The operator can control the flow rate to remain stable within the set range (e.g., 5-8 m³ / h) by adjusting the corresponding regulating valve 19. 3 / h); when the liquid level in the concentrate collection tank 3 drops to the set lower limit (e.g., 0.3m), the concentrate delivery pump 13 and the corresponding regulating valve 19 are turned off.

[0044] 4. If there is a lot of impurities in the concentrated water collection tank 3 (the differential pressure level gauge 16 monitors a difference of more than 0.2m), open the regulating valve 19 on the drain pipe 15 to drain the bottom sediment and residual liquid. After cleaning, close the regulating valve 19 on the drain pipe 15.

[0045] (III) Backwashing process of secondary reverse osmosis equipment 1. When the secondary reverse osmosis unit 1 has been running for a period of time (e.g., 72 hours) or the membrane element pressure difference exceeds the set value (e.g., 0.3 MPa), start the backwashing program.

[0046] 2. Close the regulating valves 19 on the secondary reverse osmosis inlet pipe 7 and the secondary reverse osmosis outlet pipe 8 that lead to the external system, close the regulating valve 19 on the concentrate delivery pipe 4 that leads to the circulating water tank 5, and open the regulating valves 19 on the circulation pipe 6 and the recovery pipe 9.

[0047] 3. Start the circulation pump 14. The concentrated water in the concentrated water collection tank 3 enters the circulation pipe 6 under the power of the circulation pump 14, and flows through the ozone generator 10, pH adjustment tank 11 and precision filter 12 in sequence. The ozone generator 10 generates ozone to oxidize and decompose organic matter and microorganisms in the concentrated water. The pH adjustment tank 11 adjusts the pH value of the concentrated water to 6.5-8.5 through an automatic dosing device. The precision filter 12 filters out suspended solids and particulate matter larger than 5μm.

[0048] 4. The purified backwash water enters the secondary reverse osmosis outlet water pipe 8 through the end of the circulation pipe 6, and enters the equipment in reverse from the pure water outlet of the secondary reverse osmosis equipment 1 to backwash the membrane elements and remove pollutants attached to the membrane surface.

[0049] 5. The backwashed wastewater is discharged from the secondary reverse osmosis outlet pipe 8 of the secondary reverse osmosis equipment 1 to the secondary reverse osmosis inlet pipe 7, and then flows back to the concentrate delivery pipe 4 through the regulating valve 19 on the recovery pipe 9, and finally enters the circulating water tank 5 for recycling, thus completing the backwashing process.

[0050] 6. After backwashing is completed, close the regulating valves 19 on the circulating pump 14, circulating pipe 6, and recovery pipe 9, and open the relevant regulating valves 19 on the secondary reverse osmosis inlet pipe 7, secondary reverse osmosis outlet pipe 8, and concentrate delivery pipe 4. The system will then return to normal operation.

Claims

1. A device for collecting and reusing concentrate from a secondary reverse osmosis process for deep treatment of centrifugal mother liquor, comprising a secondary reverse osmosis unit (1), a concentrate collection tank (3) whose inlet is connected to the concentrate outlet of the secondary reverse osmosis unit (1) via a concentrate outlet pipe (2), and a circulating water tank (5) whose inlet is connected to the concentrate collection tank (3) via a concentrate delivery pipe (4), characterized in that, It also includes a circulation pipe (6) connected to the concentrate delivery pipe (4) and a backwashing purification system installed on the circulation pipe (6); the secondary reverse osmosis equipment (1) is also connected to a secondary reverse osmosis inlet pipe (7) and a secondary reverse osmosis outlet pipe (8), the end of the circulation pipe (6) is connected to the secondary reverse osmosis outlet pipe (8), the secondary reverse osmosis inlet pipe (7) is connected to a recovery pipe (9), the end of the recovery pipe (9) is connected in parallel to the concentrate delivery pipe (4) and is located on the side of the circulation pipe (6) near the concentrate collection tank (3).

2. The collection and reuse device as described in claim 1, characterized in that, The backwashing purification system includes an ozone generator (10), a pH adjustment tank (11), and a precision filter (12) connected in series on the circulation pipe (6).

3. The collection and reuse device as described in claim 1, characterized in that, A concentrated water delivery pump (13) is connected in series with the concentrated water delivery pipe (4) and is located near the circulating water tank (5).

4. The collection and reuse device as described in claim 2, characterized in that, A circulation pump (14) is connected in series with the circulation pipe (6) and is located near the secondary reverse osmosis outlet pipe (8).

5. The collection and reuse device as described in claim 3, characterized in that, The concentrated water collection tank (3) is equipped with an empty pipe (15) at the bottom.

6. The collection and reuse device as described in claim 5, characterized in that, The concentrated water collection tank (3) is equipped with a differential pressure level gauge (16) and a float level gauge (17).

7. The collection and reuse device as described in claim 5, characterized in that, The concentrate delivery pipe (4) is equipped with a concentrate flow meter (18) located between the circulating water tank (5) and the concentrate delivery pump (13).

8. The collection and reuse device as described in claim 5, characterized in that, The concentrated water outlet pipe (2), concentrated water delivery pipe (4), circulation pipe (6), secondary reverse osmosis inlet pipe (7), secondary reverse osmosis outlet pipe (8), recovery pipe (9), and drain pipe (15) are all equipped with regulating valves (19).

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