Reversible cross-flow filtering membrane device

Abstract

The utility model belongs to the field of water treatment and material separation, and provides a reversible cross-flow filtering membrane device, which comprises a membrane unit, a water outlet end interface, two circulation end interfaces, a first pipeline, a second pipeline, a second pipeline and a third pipeline, the membrane unit is provided with a water production end interface and two circulation end interfaces, the two circulation end interfaces are communicated through the first pipeline, the first pipeline is provided with a two-way liquid pumping assembly, and the flow direction of fluid can be changed through the two-way liquid pumping assembly; an outlet of the water inlet pump communicates with the first pipeline, and a check valve is arranged at the outlet of the water inlet pump; and the water producing tank is communicated with the water producing end interface through a second pipeline. According to the device, the two circulation end interfaces of the membrane unit are communicated through the first pipeline to form a circulation loop, and then the reversing of circulating water flow can be realized through the two-way liquid pumping assembly. By arranging a pressure sensor, a control system and the like, the circulation direction can be automatically switched according to pressure or timing, and bidirectional cross-flow filtration of the membrane unit is realized. The accumulation of pollutants on the surface of the membrane can be avoided, the risk of membrane pollution blockage and scaling is reduced, high flux can be maintained, the membrane washing frequency is reduced, and the operation cost is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of water treatment and material separation, and specifically relates to a reversible cross-flow filtration membrane device. Background Technology

[0002] Membrane filtration technology is a common process in water treatment and material separation. It is a fundamental and crucial process in industrial water and domestic wastewater treatment, generally including two operating modes: cross-flow filtration and full-flow filtration. Cross-flow filtration refers to a process where the feed liquid, under pressure, flows into the membrane from one side, passes through the membrane surface, and flows out from the other side, while the water flow on the membrane surface is perpendicular to the feed liquid flow. In cross-flow filtration, the membrane surface is not clogged by substances deposited in the feed liquid, resulting in lower filtration resistance and faster flux recovery. Furthermore, due to the higher flow rate in cross-flow filtration, impurities adhering to the membrane surface can be carried away, exhibiting a certain degree of self-cleaning ability, and thus it is widely used.

[0003] Currently, cross-flow filtration in membrane treatment projects all adopt a unidirectional circulating cross-flow form. That is, a unidirectional pump draws concentrate from the concentrate end of the membrane unit, mixes it with the raw water, and then pumps it back into the membrane unit for multiple cross-flow filtrations. Given the installation characteristics of cross-flow filtration membrane units—multiple membrane elements are installed in series in membrane housings, and multiple membrane housings are connected in parallel for water intake—the operating states of membrane modules at different locations within different membrane housings will vary. Considering the significant differences in the length and resistance of the circulation pipes, as the operating time increases, the hydraulic conditions such as water flow velocity, circulation volume, and pressure on both sides of the membrane in different membrane housings will change, resulting in different levels of pollutant accumulation on the membrane surface.

[0004] In engineering practice, it is frequently observed that in unidirectional circulating filtration membrane elements, the amount of contaminants on the membrane surface increases and the channel fouling becomes more pronounced along the direction of the circulating water flow. Furthermore, there are significant differences in flux recovery after online backwashing and chemical cleaning. This phenomenon ultimately leads to problems such as decreased flux, reduced permeate production, more frequent backwashing and chemical cleaning, and increased operating costs for the entire membrane system.

[0005] Therefore, there is an urgent need to develop a reverse-flow cross-flow filtration membrane device and method to overcome the problem of pollutant accumulation on the membrane surface caused by different installation methods and cross-flow circulation hydraulic conditions in existing unidirectional cross-flow membrane filtration systems. Utility Model Content

[0006] To address the shortcomings of existing technologies, this invention provides a reversible cross-flow filtration membrane device. It changes the existing unidirectional cross-flow circulation design concept, effectively avoids the accumulation of pollutants on the membrane surface, reduces the risk of membrane fouling and scaling, maintains high flux, and reduces the number of membrane washing cycles.

[0007] To achieve the above objectives, this utility model adopts the following technical solution: a reversible cross-flow filtration membrane device, comprising:

[0008] The membrane unit is provided with a product water end interface and at least two circulation end interfaces. The two circulation end interfaces are connected through a first pipe, and the first pipe is provided with a bidirectional liquid extraction component.

[0009] An inlet pump, the outlet of which is connected to the first pipeline, and a check valve is provided at the outlet of the inlet pump;

[0010] The water production tank is connected to the water production end interface via a second pipe.

[0011] Preferably, the system also includes a backwash pump, the inlet of which is connected to the product water tank, a first valve on the second pipe, a second pipe between the product water end interface and the first valve and the outlet of the backwash pump, and a second valve at the outlet of the backwash pump.

[0012] Preferably, a third pipe is also included, one end of which is connected to the first pipe, the other end of which is vented, and a third valve is provided on the third pipe.

[0013] Preferably, a pressure sensor is provided at the outlet of the water production end interface.

[0014] Preferably, a pressure sensor is provided at the outlet of the circulation end interface.

[0015] Preferably, the system also includes a control system, wherein the first valve, the second valve, and the third valve are all electric valves, and the control system is electrically connected to the pressure sensor, the first valve, the second valve, the third valve, the inlet pump, the backwash pump, and the bidirectional pumping assembly, respectively.

[0016] Preferably, the bidirectional pumping assembly is a bidirectional pump.

[0017] Preferably, the bidirectional liquid extraction assembly includes a unidirectional pump, a first circulation branch, and a second circulation branch;

[0018] The one-way pump is installed on the first pipeline, and two valves are connected in series at the inlet and outlet of the one-way pump.

[0019] A valve is provided on the first circulation branch. The first end of the first circulation branch is connected to the first pipeline between the two valves at the outlet of the one-way pump. The second end of the first circulation branch is connected to the first point of the first pipeline. The two valves at the inlet of the one-way pump are located between the first point and the inlet of the one-way pump.

[0020] The second circulation branch is equipped with a valve. The first end of the second circulation branch is connected to the first pipeline between the two valves at the inlet of the one-way pump. The second end of the second circulation branch is connected to the second point of the first pipeline. The two valves at the outlet of the one-way pump are located between the second point and the outlet of the one-way pump.

[0021] The control system, serving as the control center of the entire device, consists of a PLC and supporting modules, an electrical control box, etc. It collects real-time operating data from equipment such as the inlet pump, backwash pump, unidirectional pump, valves, and pressure sensors. It automatically runs the entire membrane filtration system according to the PLC program requirements and automatically or periodically switches the cross-flow circulation direction based on the pressure difference between the inlet and outlet water to achieve bidirectional cross-flow filtration.

[0022] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0023] This invention provides a reversible cross-flow filtration membrane device. A first pipe connects the two circulation ports of the membrane unit, forming a circulation loop. A bidirectional liquid extraction component allows the circulating water flow to be reversed, thus achieving bidirectional cross-flow filtration of the membrane unit. This effectively avoids the accumulation of contaminants on the membrane surface, reduces the risk of membrane fouling and scaling, maintains high flux, reduces the frequency of membrane washing, and lowers operating costs. Attached Figure Description

[0024] Figure 1 A connection diagram of a reversible cross-flow filtration membrane device provided for an embodiment of this utility model;

[0025] Figure 2 One of the schematic diagrams of the circulation direction of a reversible cross-flow filtration membrane device provided in an embodiment of this utility model;

[0026] Figure 3 A second schematic diagram of the circulation flow direction of a reversible cross-flow filtration membrane device provided for an embodiment of this utility model;

[0027] Figure 4 A connection diagram of a reversible cross-flow filtration membrane device provided for an embodiment of this utility model;

[0028] Figure 5 This is a schematic diagram showing the connection of a multi-stage water inlet in a reversible cross-flow filtration membrane device provided in an embodiment of the present invention.

[0029] The attached diagram lists the components represented by each number as follows:

[0030] 1. Membrane unit;

[0031] 2. Inlet pump;

[0032] 3. Two-way liquid extraction assembly; 301. One-way pump; 302. First circulation branch; 303. Second circulation branch;

[0033] 4. Backwash pump;

[0034] 601. First valve; 602. Second valve; 603. Third valve;

[0035] 701, First Pipeline; 702, Second Pipeline; 703, Third Pipeline; 704, Fourth Pipeline; 705, Fifth Pipeline.

[0036] 8. Control system;

[0037] 11. Loop-end interface;

[0038] 12. Water production end interface;

[0039] 13. Water production tank. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0041] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integrally formed structures. Those skilled in the art can understand the specific meaning of these terms in this patent based on the specific circumstances.

[0042] See Figure 1 This embodiment provides a reversible cross-flow filtration membrane device, comprising:

[0043] Membrane unit 1 is a cross-flow filtration membrane module. The membrane module can be selected from microfiltration, ultrafiltration, nanofiltration, and other forms according to actual needs. Membrane unit 1 has a product water end interface 12 on its side wall, and a circulation end interface 11 at both its bottom and top. The top circulation end interface 11 is connected to the first end of the first pipe 701, and the bottom circulation end interface 11 is connected to the second end of the first pipe 701. This allows membrane unit 1 and the first pipe 701 to form a circulation loop. A bidirectional liquid extraction component 3 is provided on the first pipe 701, which is used to realize the forward and reverse transport of fluid within the circulation loop. For example, the bidirectional liquid extraction component 3 can be a bidirectional pump, which is existing technology. The bidirectional pump changes the direction of fluid flow within the circulation loop by changing the direction of the motor.

[0044] The water inlet pump 2 has its outlet connected to the first pipeline 701. A check valve is provided at the outlet of the water inlet pump 2. The water inlet pump 2 can realize the water inlet of the circulation loop, and the check valve can prevent the fluid in the circulation loop from flowing to the water inlet pump 2.

[0045] The water production tank 13 is connected to the water production end interface 12 through the second pipe 702, which can realize the water production function of the circulation loop.

[0046] In some embodiments, the bidirectional liquid extraction assembly 3 may include: a unidirectional pump 301, a first circulation branch 302, and a second circulation branch 303;

[0047] See Figure 4 The one-way pump 301 is installed on the first pipe 701. Two valves are connected in series at the inlet and outlet of the one-way pump 301. It can be understood that all four valves are installed on the first pipe 701.

[0048] A valve is provided on the first circulation branch 302. The first end of the first circulation branch 302 is connected to the first pipe 701 between the two valves at the outlet of the one-way pump 301. The second end of the first circulation branch 302 is connected to the first point of the first pipe 701. The two valves at the inlet of the one-way pump 301 are located between the first point and the inlet of the one-way pump 301.

[0049] A valve is provided on the second circulation branch 303. The first end of the second circulation branch 303 is connected to the first pipe 701 between the two valves at the inlet of the one-way pump 301. The second end of the second circulation branch 303 is connected to the second point of the first pipe 701. The two valves at the outlet of the one-way pump 301 are located between the second point and the outlet of the one-way pump 301.

[0050] For example, see Figure 2 The inlet of the one-way pump 301 is located at its lower side, and its outlet is located at its upper side. The pumping direction of the one-way pump 301 is from bottom to top. Closing the second valve at the inlet of the one-way pump 301 and the second valve at the outlet of the one-way pump 301, while opening the other valves, allows the one-way pump 301 to be turned on, enabling counter-clockwise flow of water within the circulation loop. Specifically, the fluid in membrane unit 1 flows out from the top circulation port 11, sequentially entering the second circulation branch 303, the one-way pump 301, and the first circulation branch 302, finally flowing back into membrane unit 1, thus achieving a counter-clockwise cross-flow circulation function.

[0051] For example, see Figure 3 The inlet of the one-way pump 301 is at its lower side, and its outlet is at its upper side. The pumping direction of the one-way pump 301 is from bottom to top. With the valves on the first circulation branch 302 and the second circulation branch 303 closed and the other valves open, starting the one-way pump 301 allows for clockwise flow within the circulation loop. Specifically, the fluid in membrane unit 1 flows out from the bottom circulation port 11, enters the one-way pump 301, and finally flows back into membrane unit 1, achieving a clockwise cross-flow circulation function.

[0052] Therefore, by controlling the opening and closing of the valves inside the bidirectional pumping assembly 3, the direction of fluid flow in the circulation loop can be changed.

[0053] In summary, the reversible cross-flow filtration membrane device provided in this embodiment connects the two circulation end interfaces 11 of the membrane unit 1 through the first pipe 701 to form a circulation loop. Then, the bidirectional liquid pumping component 3 reverses the water flow within the circulation loop, thereby achieving bidirectional cross-flow filtration of the membrane unit 1. This effectively avoids the accumulation of contaminants on the membrane surface, reduces the risk of membrane fouling and scaling, maintains high flux, reduces the frequency of membrane washing, and lowers operating costs.

[0054] The reversible cross-flow filtration membrane device provided in this embodiment also includes a backwash pump 4, see [link to documentation]. Figure 4 The inlet of the backwash pump 4 is connected to the product water tank 13. A first valve 601 is installed on the second pipe 702. The second pipe 702 between the product water end interface 12 and the first valve 601 is connected to the outlet of the backwash pump 4. A second valve 602 is installed at the outlet of the backwash pump 4. The second valve 602 is normally closed. When backwashing is required, the first valve 601 is closed, and the second valve 602 and the backwash pump 4 are opened, allowing the water in the product water tank 13 to flow back into the membrane unit 1, thus realizing the backwashing function.

[0055] The reversible cross-flow filtration membrane device provided in this embodiment also includes a third pipe 703, which is a drain pipe. One end of the third pipe 703 is connected to the first pipe 701, and the other end of the third pipe 703 is vented. A third valve 603 is provided on the third pipe 703. The third valve 603 is normally in the closed state. When sewage needs to be discharged, the third valve 603 is opened, allowing the water in the first pipe 701 to be discharged through the third pipe 703, thus realizing the sewage discharge function.

[0056] In this embodiment, a pressure sensor is installed at the outlet of the product water interface 12. A pressure sensor is also installed at the outlet of the circulation interface 11. The pressure at the product water interface 12 and the circulation interface 11 can be detected in real time.

[0057] The reversible cross-flow filtration membrane device provided in this embodiment also includes a control system 8, which is electrically connected to a pressure sensor, a first valve 601, a second valve 602, a third valve 603, an inlet pump 2, a backwash pump 4, and a bidirectional liquid extraction assembly 3.

[0058] In this embodiment, all valves can be electric valves. The control system 8 consists of a PLC and supporting modules, an electrical control box, etc. It collects the operating data of the inlet pump 2, backwash pump 4, bidirectional liquid extraction assembly 3, electric valves, pressure sensors, and other equipment in real time. It automatically runs the entire membrane filtration system according to the PLC program requirements and automatically or periodically switches the cross-flow circulation direction according to the pressure difference between the inlet and outlet water to achieve bidirectional cross-flow filtration.

[0059] The reversible cross-flow filtration membrane device provided in this embodiment can employ multi-stage water inlet. For example, see... Figure 5 A check valve is installed at the outlet of the inlet pump 2. The end of the check valve away from the inlet pump 2 is connected to the first pipe 701 via the fourth pipe 704, and the other end of the check valve is also connected to the first pipe 701 via the fifth pipe 705. The connection points of the fourth pipe 704 and the first pipe 701, and the connection points of the fifth pipe 705 and the first pipe 701, are located at different positions, respectively on the front and rear sides of the bidirectional pumping assembly 3. This allows for multi-stage water intake and flexible operation.

[0060] Example 1

[0061] A coal mine water treatment station with a treatment capacity of 200m³ 3 The main pollutants in the influent are suspended solids (primarily rock powder and coal powder), inorganic ions, some organic matter, and bacteria. Suspended solids are 500-2000 mg / L, E. coli 1700-14000 CFU / L, and oil ≤10 mg / L, which are the main treatment indicators. The project uses a pretreatment filter + ultrafiltration system to treat the mine water. The effluent meets and exceeds the requirements for underground fire fighting and sprinkler water in the "Code for Design of Fire Fighting and Sprinkler System in Coal Mines" (GB50383-2016), namely turbidity <1 NTU, suspended solids <0.1 mm, E. coli <3 CFU / L, and oil ≤0.1 mg / L. The pretreatment filter serves as a protective step for membrane filtration, while the ultrafiltration section is the main facility for reducing turbidity and removing suspended solids, E. coli, and oil. This project uses two sets of equipment with a treatment capacity of 100 m³ / h. 3 A reversible cross-flow filtration membrane device with a flow rate of / h enables it to meet effluent standards.

[0062] This mine water treatment station is equipped with two independently operating, reversible cross-flow filtration membrane devices. For details, please refer to... Figure 1 , Figure 4 A reversible cross-flow filtration membrane device includes: membrane unit 1, inlet pump 2, bidirectional liquid extraction assembly 3, backwash pump 4, pressure sensor, electric valve, piping and control system 8.

[0063] The membrane unit 1, bidirectional pumping assembly 3, pressure sensor, electric valve, pipeline and control system 8 are all skid-mounted on the membrane frame; 3 feed pumps 2 (2 in operation and 1 standby) are provided, using mining explosion-proof submersible pumps (with floats), with a flow rate of 125-150 m³ / h. 3 / h, head 25-50m; 1 backwash pump 4, selected as a mining explosion-proof submersible pump (with float), flow rate 125-150m³ / h, head 25-50m; 4 units of backwash pump, selected as a mining explosion-proof submersible pump (with float), flow rate 125-150m³ / h, head 25-50m; 1 unit of backwash pump 4, selected as a mining explosion-proof submer 3 / h, head 15-25m;

[0064] Given that previous unidirectional cross-flow filtration methods often resulted in contaminant accumulation on the membrane surface due to variations in membrane module installation and cross-flow circulation hydraulic conditions, the treatment plant selected membrane unit 1 as a cross-flow filtration, fouling-resistant, and oil-resistant ultrafiltration membrane unit, with a single unit treatment capacity of 100m³. 3 The membrane filtration system, with a capacity of [number] h, consists of 88 membrane housings and 176 8040 ultrafiltration membrane modules. Each membrane housing contains two 8040 ultrafiltration membrane modules connected in series to form an ultrafiltration membrane unit. The membrane housings are installed vertically in parallel. Each membrane housing is equipped with two circulation end interfaces 11 and one product water end interface 12. The circulation end interfaces 11 and product water end interfaces 12 can be configured according to the installation method of the membrane modules. The two circulation end interfaces 11 are connected to the bidirectional liquid extraction component 3 through the first pipe 701 to realize cross-flow circulation of raw water. The product water end interface 12 is connected to the product water tank 13, backwash pump 4, etc. through pipes to realize functions such as product water production and backwashing.

[0065] The bidirectional pumping assembly 3 consists of one unidirectional pump 301, one set of automatic switching electric valves, and matching switching pipelines. It forms a combination of one main circulation pipeline and two bypass pipelines (first circulation branch 302 and second circulation branch 303) around the unidirectional pump 301. The unidirectional pump 301 is a horizontal centrifugal pump operating in one direction with a flow rate of 200-300 m³ / h. 3 / h, head 15-25m; the automatic switching electric valve group consists of 6 electric valves, two of which are installed before the unidirectional pump 301, two after the unidirectional pump 301, and one valve per pipeline. By changing the opening and closing of the electric valves on different pipelines, the direction of water flow in the pipeline is changed and the flow is interrupted, realizing bidirectional cross-flow circulation.

[0066] Pressure sensors are installed on the pipelines at the circulation end interface 11 and the product water end interface 12 to monitor the pressure values ​​at the circulation end interface 11 and the product water end interface 12 of the membrane unit 1 online and provide real-time feedback to the control system 8. The pressure sensor has a measurement range of 0-0.5 MPa and outputs a 4-20 mA signal. Several pressure gauges are also provided to display the pressure changes at the circulation end and the product water end of the membrane unit 1 locally.

[0067] The control system 8 serves as the control center of the entire device. It consists of a PLC and supporting modules, an electrical control box, etc. It collects the operating data of equipment such as the inlet pump 2, backwash pump 4, bidirectional liquid extraction assembly 3, electric valves, and pressure sensors in real time. It automatically runs the entire membrane filtration system according to the PLC program requirements and automatically or periodically switches the cross-flow circulation direction based on the cross-membrane pressure difference to achieve bidirectional cross-flow filtration.

[0068] Based on past experience with unidirectional circulation crossflow membrane fouling, this mine water treatment station adopts a dual-parameter operation mode of time and pressure.

[0069] During the rainy season or after the underground water tank is emptied, when the mine water production is high but the influent water quality is good, the circulation crossflow direction is automatically reversed every 7-10 days (the time can be modified according to actual production, changes in influent water quality, etc.). That is, the circulation crossflow direction in membrane unit 1 is changed by the bidirectional pumping component 3 to flush away the pollutants accumulated on the membrane surface during the previous unidirectional circulation, reducing the risk of membrane fouling. At the same time, the pressure difference between the circulation end and the product water end of membrane unit 1 is monitored. If the value continues to increase and the circulation end pressure is greater than 0.3 MPa, an alarm is issued and the circulation crossflow direction is reversed 1 hour after the alarm. Each reversal of the circulation crossflow direction must be accompanied by the operation of the unidirectional pump 301, electric valve, and other supporting actions.

[0070] During other periods, the circulating crossflow direction is automatically reversed every 1-3 days (the time can be modified according to actual production, changes in incoming water quality, etc.). At the same time, the pressure difference between the circulation end and the product water end of membrane unit 1 is monitored, and the corresponding reverse operation is performed according to the pressure difference.

[0071] Based on actual operating results, the effluent quality is good, the membrane flux decrease is not significant, and the membrane chemical cleaning cycle has been reduced from once a month to once a quarter, which greatly saves chemical cleaning agents and reduces operating costs.

[0072] Example 2

[0073] A company's water purification plant draws surface water, treats it, and then supplies it with domestic water for the plant area. Its treatment capacity is 100m³. 3 Currently, the effluent meets the "Standards for Drinking Water Quality" (GB 5749-2006). However, with rising living standards and stricter national standards, the water treatment plant needs upgrading to meet the "Standards for Drinking Water Quality" (GB 5749-2022). This involves adding a nanofiltration membrane filtration process to the existing "coagulation sedimentation + filtration + disinfection" process to ensure the effluent meets the new standards. Therefore, this project will add two 50m³ / h filters after the V-type filter. 3 / h reversible cross-flow filtration membrane device.

[0074] Specifically, the reversible cross-flow filtration membrane device includes: membrane unit 1, inlet pump 2, bidirectional liquid extraction assembly 3, backwash pump 4, pressure sensor, electric valve, pipeline and control system 8;

[0075] The membrane unit 1, bidirectional pumping assembly 3, pressure sensor, electric valve, piping and control system 8 are all skid-mounted on the membrane frame; in conjunction with this, three inlet pumps 2 (2 in operation and 1 standby) are installed in the original intermediate water tank, using dry self-priming pumps with a flow rate of 50-75 m³ / h. 3 / h, head 60-75m; 1 backwash pump 4, located in the effluent tank, flow rate 45-75m 3 / h, head 40-50m.

[0076] Given the problems of easy accumulation of pollutants on the membrane surface caused by the different installation methods and hydraulic conditions of cross-flow filtration in traditional unidirectional cross-flow filtration, the treatment plant selected a cross-flow filtration nanofiltration membrane unit 1 that is fouling-resistant and oil-resistant, with a single unit treatment capacity of 50m³. 3 The membrane filtration system with a capacity of [number] h consists of 56 nanofiltration membrane units, with the membrane housings of the nanofiltration membrane units installed horizontally in parallel. Each membrane housing is equipped with two circulation end interfaces 11 and one product water end interface 12, wherein the circulation end interfaces 11 and product water end interfaces 12 can be configured according to the membrane module installation method; the two circulation end interfaces 11 are connected to the bidirectional liquid extraction component 3 through pipelines to realize cross-flow circulation of raw water; the product water end interface 12 of membrane unit 1 is connected to the product water tank 13, backwash pump 4, etc. through pipelines to realize product water and backwash functions;

[0077] The bidirectional pumping assembly 3 consists of one unidirectional pump 301, one set of automatic switching electric valves, and matching switching pipelines. It forms a combination of one main circulation pipeline and two bypass pipelines (first circulation branch 302 and second circulation branch 303) around the unidirectional pump 301. The unidirectional pump 301 is a bidirectional pipeline pump, and its bidirectional operation is achieved through an electrical circuit, thus realizing the reverse flow of the cross-flow circulation. Its flow rate is 300-400 m³ / h. 3 / h, head 15-20m; the automatic switching electric valve group consists of 6 electric valves, two of which are installed before the unidirectional pump 301, two after the unidirectional pump 301, and one valve per pipeline. By changing the opening and closing of the electric valves on different pipelines, the direction of water flow in the pipeline is changed and the flow is interrupted, realizing bidirectional cross-flow circulation.

[0078] Pressure sensors are installed on the pipelines at the circulation end interface 11 and the product water end interface 12 to monitor the pressure values ​​at the circulation end interface 11 and the product water end interface 12 of the membrane unit 1 online and provide real-time feedback to the control system 8. The pressure sensor has a measurement range of 0-0.7 MPa and outputs a 4-20 mA signal. Several pressure gauges are also provided to display the pressure changes at the circulation end and the product water end of the membrane unit 1 locally.

[0079] The control system 8 serves as the control center of the entire device. It consists of a PLC and supporting modules, an electrical control box, etc. It collects the operating data of equipment such as the inlet pump 2, backwash pump 4, bidirectional liquid extraction assembly 3, electric valves, and pressure sensors in real time. It automatically runs the entire membrane filtration system according to the PLC program requirements and automatically or periodically switches the cross-flow circulation direction based on the cross-membrane pressure difference to achieve bidirectional cross-flow filtration.

[0080] Based on past experience with unidirectional circulation crossflow membrane fouling, this purification plant adopts a dual-parameter operation mode of time and pressure.

[0081] During the rainy season, when the water quality of the source water is poor, the circulating crossflow direction is automatically reversed every 1-3 days (the time can be modified according to actual production, changes in incoming water quality, etc.) to flush away the pollutants accumulated on the membrane surface during the previous unidirectional circulation cycle, reducing the risk of membrane fouling. At the same time, the pressure difference between the circulation end and the product water end of membrane unit 1 is monitored. If the value continues to increase and the circulation end pressure is greater than 0.7 MPa, an alarm is issued and the circulating crossflow direction is reversed 1 hour after the alarm. Each reversal of the circulating crossflow direction must be accompanied by the operation of the unidirectional pump 301, electric valve, and other supporting functions.

[0082] At other times, the circulating crossflow direction is automatically reversed every 7-10 days (the time can be modified according to actual production, changes in incoming water quality, etc.). At the same time, the pressure difference between the circulation end and the product water end of membrane unit 1 is monitored, and the corresponding reverse operation is performed according to the pressure difference.

[0083] Based on actual operating results, the effluent quality is good, the membrane flux decrease is not significant, and the membrane chemical cleaning cycle has been reduced from once a month to once a quarter, which greatly saves chemical cleaning agents and reduces operating costs.

[0084] Example 3

[0085] The reversible cross-flow filtration membrane device provided in this embodiment is used in a demonstration project for underground reuse of mine water in a coal mine.

[0086] Construction scale: 200m 3 / h

[0087] Treatment Technology: Green Short-Distance Mine Water Treatment Technology

[0088] Process flow: booster pump → pretreatment filter → reversible ultrafiltration unit → reuse

[0089] System configuration: 2 sets of 100m 3 / h Reversible ultrafiltration unit, total installed capacity of 160kW

[0090] Site area: Approximately 270m² 2 (Existing chamber renovation)

[0091] Influent water quality: Suspended solids 500-2000 mg / L

[0092] Water quality: Meets the requirements of the "Design Code for Fire Fighting and Sprinkler System in Coal Mines" (GB50383-2016)

[0093] The original chemical cleaning cycle was increased from 15 days to 60 days, which greatly reduced the frequency of chemical cleaning, saved chemicals, and reduced operating costs.

[0094] The mechanisms, components, and parts in this invention that are not specifically described are all existing structures in the prior art and can be purchased directly from the market.

[0095] In the description of this utility model, it should be understood that the terms "upper," "lower," "left," and "right," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on this utility model. Furthermore, "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "multiple" means two or more.

[0096] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A reversible cross-flow filtration membrane device, characterized in that, include: The membrane unit (1) is provided with a product water end interface (12) and at least two circulation end interfaces (11). The two circulation end interfaces (11) are connected through a first pipe (701). The first pipe (701) is provided with a bidirectional liquid extraction assembly (3). The water inlet pump (2) has its outlet connected to the first pipeline (701), and a check valve is provided at the outlet of the water inlet pump (2); The water production tank (13) is connected to the water production end interface (12) via a second pipe (702).

2. The reversible cross-flow filtration membrane device according to claim 1, characterized in that, It also includes a backwash pump (4), the inlet of which is connected to the product water tank (13), a first valve (601) is provided on the second pipe (702), the second pipe (702) between the product water end interface (12) and the first valve (601) is connected to the outlet of the backwash pump (4), and a second valve (602) is provided at the outlet of the backwash pump (4).

3. The reversible cross-flow filtration membrane device according to claim 2, characterized in that, It also includes a third pipe (703), one end of which is connected to the first pipe (701), the other end of which is vented, and a third valve (603) is provided on the third pipe (703).

4. The reversible cross-flow filtration membrane device according to claim 3, characterized in that, A pressure sensor is provided at the outlet of the water production port (12).

5. The reversible cross-flow filtration membrane device according to claim 4, characterized in that, A pressure sensor is provided at the outlet of the circulation end interface (11).

6. The reversible cross-flow filtration membrane device according to claim 5, characterized in that, It also includes a control system (8), wherein the first valve (601), the second valve (602), and the third valve (603) are all electric valves, and the control system (8) is electrically connected to the pressure sensor, the first valve (601), the second valve (602), the third valve (603), the water inlet pump (2), the backwash pump (4), and the bidirectional liquid extraction assembly (3), respectively.

7. The reversible cross-flow filtration membrane device according to claim 1, characterized in that, The bidirectional pumping assembly (3) is a bidirectional pump.

8. The reversible cross-flow filtration membrane device according to claim 1, characterized in that, The bidirectional liquid extraction assembly (3) includes a unidirectional pump (301), a first circulation branch (302), and a second circulation branch (303); The one-way pump (301) is installed on the first pipeline (701), and two valves are connected in series at the inlet and outlet of the one-way pump (301); The first circulation branch (302) is equipped with a valve. The first end of the first circulation branch (302) is connected to the first pipeline (701) between the two valves at the outlet of the one-way pump (301). The second end of the first circulation branch (302) is connected to the first point of the first pipeline (701). The two valves at the inlet of the one-way pump (301) are located between the first point and the inlet of the one-way pump (301). The second circulation branch (303) is equipped with a valve. The first end of the second circulation branch (303) is connected to the first pipe (701) between the two valves at the inlet of the one-way pump (301). The second end of the second circulation branch (303) is connected to the second point of the first pipe (701). The two valves at the outlet of the one-way pump (301) are located between the second point and the outlet of the one-way pump (301).

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