Ultrafiltration membrane device for wastewater treatment of finishing machine

Abstract

The utility model discloses an ultrafiltration membrane device for treating wastewater of a finishing machine, and belongs to the technical field of environment-friendly sewage treatment. Comprising a membrane assembly, a compressed air backwashing assembly, a clear water backwashing assembly and a forward flushing assembly, the membrane assembly comprises a membrane shell and a plurality of layers of membrane discs arranged in the membrane shell through a central shaft, and the central shaft is connected with the water production port; the compressed air backwashing assembly comprises a backwashing air inlet pipe and an air compressor; the clean water backwashing assembly comprises a cleaning water inlet pipe and a cleaning pump; the forward flushing assembly comprises a forward flushing pipe. The cross-flow condition of the membrane surface is improved by utilizing the scouring action of the water distribution pipe and the shearing action of the rotary membrane assembly, and the formation of a membrane surface pollution layer is slowed down. Automatic air blowing and air-water backwashing are adopted, so that pollutants on the surface of the membrane are effectively removed. Compared with a conventional tubular ceramic membrane, the tubular ceramic membrane is high in operation efficiency, low in energy consumption, convenient to clean and recover, high in system automation degree and small in equipment occupied area.

Description

Technical Field

[0001] The utility model belongs to the technical field of environmental protection sewage treatment, and particularly relates to an ultrafiltration membrane device for treating the wastewater of a skin pass mill. Background Art

[0002] A skin pass mill is a device used to improve the surface quality of products and change the surface finish. The post-treatment cleaning system of the skin pass mill is divided into two parts: high-pressure cleaning and general cleaning. There is a spray beam above and below the inlet of the cleaning machine, and the sprayed water comes from an underground water tank and is pumped up by a high-pressure pump. Immediately behind, there is a set of squeezing rollers. After the first set of squeezing rollers, there is a spray beam above and below the middle part of the cleaning machine, and the sprayed water comes from the desalination water pipe network with relatively low pressure, followed by a set of squeezing rollers. The cleaned water is filtered and then recycled to the underground water tank.

[0003] With the development of membrane materials and membrane technology, membrane separation technology, as a new type of water treatment technology, has been widely used in sewage treatment fields such as biology, chemical engineering, medicine, food, and municipal engineering. Membrane separation technology has become the preferred choice for upgrading wastewater treatment standards and reusing reclaimed water. Commonly used ultrafiltration membrane modules mainly include hollow fiber membranes, tubular membranes, and flat membranes.

[0004] Traditional hollow fiber membrane modules and flat membrane modules generally use perforated aeration at the bottom of the membrane module for aeration. However, this aeration method has problems of uneven aeration and insufficient hydraulic scouring. In order to improve the cleaning effect on the membrane surface, a relatively large aeration volume is usually required, and the fouling resistance performance of the membrane module is poor. Tubular ultrafiltration membranes rely on a large circulation flow rate to increase the cross-flow velocity on the membrane surface. Although they have strong fouling resistance performance, they have high operating energy consumption and large equipment floor area.

[0005] The wastewater from the skin pass mill flushing contains oils, iron powder, zinc powder, and various complex organic substances (such as surfactants, lubricants, etc.). These pollutants will all cause fouling to the membrane. Therefore, there is an urgent need for a suitable membrane module with a small floor area and stable operation for treating the wastewater of the skin pass mill. Summary of the Utility Model

[0006] Aiming at the deficiencies existing in the prior art, the technical problem to be solved by the utility model is to provide an ultrafiltration membrane device for treating the wastewater of a skin pass mill, which is used to treat the flushing wastewater of the skin pass mill.

[0007] To solve the above technical problems, the technical scheme adopted by the utility model is as follows:

[0008] An ultrafiltration membrane device for temper mill wastewater treatment, comprising a membrane module, a compressed air backwashing assembly, a clean water backwashing assembly, and a forward flushing assembly; the membrane module includes a membrane housing and multiple layers of membrane discs disposed within the membrane housing through a central shaft, and the central shaft is connected to a water production port; the compressed air backwashing assembly includes a backwashing intake pipe and an air compressor, and the air compressor is connected to the water production port through the backwashing intake pipe; the clean water backwashing assembly includes a cleaning intake pipe and a cleaning pump, and the cleaning pump is connected to the water production port through the cleaning intake pipe; the forward flushing assembly includes a forward flushing pipe.

[0009] The membrane module further includes a bracket and a water distribution pipe and a water outlet disposed on the bracket.

[0010] The water distribution pipe is connected to the intake pipe and the forward flushing pipe.

[0011] The water distribution pipe is provided with branch pipes, and the branch pipes are sequentially arranged between two adjacent membrane discs

[0012] The number of the branch pipes is one more than the number of the membrane discs.

[0013] The number of membrane discs in a single membrane module is 10 to 30, and the distance between two adjacent membrane discs is 40 to 50 mm.

[0014] Small holes are provided on the branch pipes, and the small holes are symmetrically arranged at an angle of 45° with respect to the vertical direction of the membrane discs and the branch pipes.

[0015] The membrane discs include a support layer and a membrane layer. The membrane layer is double-sided and includes a transition layer and a membrane filtration layer. The support layer is provided with a diversion groove. The transition layer is located between the support layer and the membrane filtration layer. The transition layer has a three-layer structure. The inner layer of the transition layer covers the support layer. The inner layer pore size of the filtration layer is 10 to 20 times that of the outer layer. The middle layer pore size of the transition layer is 5 to 10 times that of the inner layer of the filtration layer. The inner layer pore size of the transition layer is 3 to 5 times that of the membrane filtration layer pore size. The membrane filtration layer covers the outer layer of the filtration layer. The thickness of the membrane filtration layer is 10 to 15 μm. The outer layer thickness of the transition layer is 30 to 40 μm. The middle layer thickness of the transition layer is 200 to 500 μm. The inner layer thickness of the transition layer is 1 to 2 mm. The thickness of the support layer is 3 to 5 mm. The diversion groove is spirally distributed along the center of the membrane disc. The central shaft is provided with water guiding holes, and the water guiding holes are communicated with the diversion grooves of the membrane discs.

[0016] The filtration accuracy of the membrane discs is 5 to 30 nm.

[0017] Compared with the prior art, the technical advantages of the present utility model include:

[0018] 1) The present utility model utilizes the scouring action of the water distribution pipe and the shearing action of the rotating membrane module to improve the cross-flow conditions on the membrane surface and slow down the formation of the fouling layer on the membrane surface.

[0019] 2) The utility model adopts automatic air blowing and air-water backwashing, effectively removing pollutants on the membrane surface, improving the anti-pollution performance of the membrane surface, and prolonging the service life of the membrane.

[0020] 3) Compared with conventional tubular ceramic membranes, the utility model has high operating efficiency, low energy consumption, is easy to clean and recover, has a high degree of system automation, and a small footprint of the equipment. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of an ultrafiltration membrane device for bright annealing wastewater treatment;

[0022] Figure 2 It is a schematic structural diagram of a membrane disk.

[0023] The reference numerals are: 1 - membrane shell; 2 - bracket; 3 - water distribution pipe; 4 - water outlet; 5 - water production port; 6 - central axis; 7 - membrane disk; 8 - sealing jacket; 9 - motor; 10 - feed water pump; 11 - feed water tank; 12 - feed water pipe; 13 - aeration pipe; 14 - drain pipe; 15 - forward flushing pipe; 16 - feed water tank inlet air pipe; 17 - concentrated water return pipe; 18 - chemical cleaning concentrated water return pipe; 19 - backwashing inlet air pipe; 20 - water production pipe; 21 - cleaning inlet water pipe; 22 - air compressor; 23 - water production tank; 24 - cleaning pump; 25 - transition layer; 26 - membrane filtration layer; 27 - support layer; 28 - diversion groove; 29 - cleaning water tank; 30 - chemical cleaning pump; 31 - chemical cleaning water production return pipe. Detailed Embodiments

[0024] The following further clarifies the present utility model in conjunction with the drawings and specific embodiments. These embodiments are implemented on the premise of the technical solution of the present utility model. It should be understood that these embodiments are only used to illustrate the present utility model and not to limit the scope of the present utility model.

[0025] As Figure 1 shown, an ultrafiltration membrane device for bright annealing wastewater treatment includes a membrane module, a bracket 2, a feed water tank 11, a motor 9, an air compressor 22, a feed water pump 10, a cleaning pump 24, and a water production tank 23. The membrane module includes a membrane shell 1, a bracket 2, a water distribution pipe 3, a water outlet 4, a water production port 5, a central axis 6, a membrane disk 7, and a sealing jacket 8.

[0026] The membrane housing 1 is cylindrical and made of stainless steel. The bottom of the membrane housing 1 is fixed to the bracket 2 by screws, and the membrane housing 1 can be removed by removing the screws. The water outlet 4 and the water distribution pipe 3 are fixed to the bracket 2, and the bracket 2 is arranged on the water inlet tank 11. Multiple groups of membrane modules and the bracket 2 are arranged side by side on the water inlet tank 11; the motor 9 is located below the membrane module, and the motor 9 is connected to the central shaft 6 through a coupling fixed to the bracket 2. The bottom of the central shaft 6 is connected to the motor 9 through a sealed bearing; the top of the membrane housing 1 is fixed to the cylinder by screws, and the top of the central shaft 6 is connected to the water production outlet 5 through a sealed bearing; the membrane discs 7 and the sealing jacket 8 are fixedly arranged on the central shaft 6 at intervals.

[0027] Among them, the water distribution pipe 3 is connected to the water inlet pipe 12 and the forward flushing pipe 15, and the water production outlet 5 is connected to the water production pipe 20 and the cleaning water inlet pipe 21. Finally, the pickling wastewater after being cleaned is temporarily stored in the water production tank 23 through the water production outlet 5 and the water production pipe 20 for subsequent reuse. The water outlet 4 is connected to the water outlet pipe 18 and the concentrated water return pipe 17.

[0028] The water distribution pipe 3 is provided with branch pipes, and the branch pipes are arranged between two adjacent membrane discs 7 in sequence. The number of branch pipes is 1 more than the number of membrane discs 7; small holes are provided on the branch pipes, and the small holes are symmetrically arranged at an angle of 45° with the vertical direction of the membrane discs 7 and the branch pipes. The number of small holes on a single branch pipe is 6 - 8, and the diameter of the small holes is 5 - 10 mm. Multiple branch pipes can be arranged between two adjacent membrane discs 7 to reduce the distance between two adjacent membrane discs 7 and reduce the height of the membrane module. The diameter of the branch pipes is 10 - 20 mm, and the distance between two membrane discs 7 is 40 - 50 mm.

[0029] Multiple groups of membrane modules are arranged. The number of membrane discs 7 in a single membrane module is 10 - 30, and the membrane area of a single membrane module is 1 - 15 m 2 . The membrane disc 7 includes a support layer 27, a transition layer 25, a membrane filtration layer 26 and a diversion groove 28 ( Figure 2 ), the membrane disc 7 is made of silicon carbide, the filtration accuracy of the membrane disc 7 is 5 - 30 nm, the membrane water production flux of the membrane disc 7 is 100 - 200 L / (m 2 ·h), and the operating pressure of the membrane disc 7 is 0.15 - 0.25 Mpa.

[0030] The membrane disc 7 includes a support layer 27 and a membrane layer. The membrane layer is double-sided and includes a transition layer 25 and a membrane filtration layer 26. The support layer 27 is provided with a diversion groove 28. The transition layer 25 is located between the support layer 27 and the membrane filtration layer 26. The transition layer 25 has a three-layer structure. The inner layer of the transition layer 25 covers the support layer 27. The pore size of the inner layer of the filtration layer 25 is 10 to 20 times that of the outer layer. The pore size of the middle layer of the transition layer 25 is 5 to 10 times that of the inner layer of the filtration layer 25. The pore size of the inner layer of the transition layer 25 is 3 to 5 times that of the membrane filtration layer 26. The membrane filtration layer 26 covers the outer layer of the filtration layer 25. The thickness of the membrane filtration layer 26 is 10 to 15 μm. The thickness of the outer layer of the transition layer 25 is 30 to 40 μm. The thickness of the middle layer of the transition layer 25 is 200 to 500 μm. The thickness of the inner layer of the transition layer 25 is 1 to 2 mm. The thickness of the support layer 27 is 3 to 5 mm. The diversion groove 28 is spirally distributed along the center of the membrane disc 7.

[0031] The central shaft 6 is a hollow tube. The central shaft 6 is fixed at the center of the membrane housing 1 through couplings at both ends of the membrane housing 1. The central shaft 6 is provided with water guiding holes. The outlet of the diversion groove 28 of the membrane disc 7 is communicated with the water guiding holes. The membrane disc 7 and the sealing jacket 8 are fixedly arranged on the central shaft 6 at intervals. The distance between adjacent membrane discs 7 is 2 to 3 cm larger than the diameter of the branch pipe of the water distribution pipe 3. The rotation speed of the central shaft 6 is less than 300 r / min. The central shaft 6 is frequency-controlled by a motor 9.

[0032] The water inlet tank 11 adopts a strengthened structure. The bottom of the water inlet tank 11 is provided with a water inlet pump 10 and an aeration pipe 13. The water inlet pump 10 adopts a submersible sewage pump. The flow-through components of the submersible sewage pump are made of wear-resistant materials. The flow ratio of the water inlet pump 10 to the water production pipe 20 is 2:1. The aeration intensity of the water inlet tank 11 is 0.5 to 1.0 L / (m 2 ·s). The head of the water inlet pump 10 is 20 to 30 m. The hydraulic retention time of the water inlet tank 11 is 10 to 15 min. A liquid level gauge is arranged in the water inlet tank 11 to control the operation of the water inlet pump 10. When the liquid level is low, the water inlet pump 10 automatically stops running. Pressure gauges and flow meters are arranged on the water production pipe 20, the cleaning water inlet pipe 21, the drain pipe 14, the water inlet pipe 12, the backwashing air inlet pipe 19, the forward flushing pipe 15, and the water inlet pipe of the water inlet tank 16. Electric valves or pneumatic valves are arranged on the pipeline to realize automatic control during membrane operation and cleaning.

[0033] The chemical cleaning concentrated water return pipe 18 and the chemical cleaning produced water return pipe 31 are connected to the water inlet of the cleaning water tank 29. The water outlet of the cleaning water tank 29 is connected to the chemical cleaning pump 30. The water outlet of the chemical cleaning pump 30 is connected to the water distribution pipe 3. During operation, a part of the concentrated water is continuously discharged through the drain pipe 14.

[0034] The air compressor 22 is connected to the backwashing inlet pipe 19 to provide air source for the backwashing inlet pipe 19 and conduct air backwashing on the membrane discs 7. The air compressor 22 is connected to the forward flushing pipe 15 to provide air source for the forward flushing pipe 15 and conduct air flushing on the membrane discs 7. The air compressor 22 is connected to the aeration pipe 13 through the water inlet tank inlet pipe 16 to provide air source for the aeration pipe 13, and uses compressed air for aeration and stirring to prevent zinc powder and iron powder in the pickling wastewater from depositing at the bottom of the water inlet tank 11.

[0035] The working principle of the present utility model is as follows: The pickling wastewater in the water inlet tank 11 is lifted to the water distribution pipe 3 of the membrane module by the water inlet pump 10. During operation, the operating pressure and drainage flow rate are adjusted by adjusting the valves on the concentrated water return pipe 17 and the drain pipe 14. The product water flow rate / (product water flow rate + drainage flow rate) = membrane treatment product water rate, and the membrane treatment product water rate is controlled to be 90% - 95%. During the operation of the pickling wastewater, pollutants are continuously concentrated, and a part of the concentrated water is discharged through the drain pipe 14. After continuous operation for 15 - 30 minutes, a single compressed air backwashing is carried out using the backwashing inlet pipe 19, or backwashing is carried out using the cleaning pump 24 and the cleaning inlet pipe 21, or air-water backwashing can also be carried out simultaneously. During backwashing, operation needs to be stopped first. During the operation process, the membrane surface is subjected to air-water flushing once every 5 - 10 minutes using the forward flushing pipe 15. Air-water flushing does not require shutdown. The flow rate of the product water pipe 20 is controlled by adjusting the operating pressure, and the change of the product water flow rate is monitored by a flowmeter. When the product water flow rate drops by more than 10 - 15%, chemical cleaning is carried out. During chemical cleaning, due to the temperature resistance and acid and alkali resistance of the ceramic membrane, the cleaning efficiency for oil substances can be improved in a high-temperature alkaline environment. Compressed air is used for aeration and stirring in the water inlet tank 11 to prevent zinc powder and iron powder in the pickling wastewater from depositing at the bottom of the water inlet tank 11.

[0036] The cleaning methods for the pickling wastewater during operation include forward flushing and backwashing. During forward flushing, the valve on the forward flushing pipe 15 is opened, and compressed air enters the water distribution pipe 3 from the forward flushing pipe 15. The compressed air and the pickling wastewater flow from the water distribution pipe 3 to the surface of the membrane discs 7 to conduct air-water flushing on the membrane surface. During backwashing, operation needs to be stopped first, and then the valve on the cleaning inlet pipe 21 is opened, and the cleaning pump 24 is started. The cleaning pump 24 sends the product water of the membrane module from the product water outlet 5 into the membrane module, and uses the product water of the membrane module to conduct backwashing on the membrane discs 7. During backwashing, the product water of the membrane module flows from the diversion groove 28 of the membrane discs 7 to the outside of the membrane discs 7 to conduct reverse flushing on the pollutants on the surface of the membrane discs 7. During backwashing, the valve on the backwashing inlet pipe 19 is opened, and compressed air enters the membrane module from the product water outlet 5, and then the compressed air flows from the inside of the membrane discs 7 to the outside of the membrane discs 7 to conduct reverse flushing on the surface of the membrane discs 7. During backwashing, the valve on the cleaning inlet pipe 21 is opened, the cleaning pump 24 is started, and at the same time the valve on the backwashing inlet pipe 19 is opened, then air-water backwashing is carried out.

[0037] When the membrane module is chemically cleaned, it is necessary to stop the machine first, add cleaning agent to the cleaning water tank 29, and then open the valves on the outlet pipeline of the chemical cleaning pump 30, the valve on the chemical cleaning concentrated water return pipe 18, and the valve on the chemical cleaning product water return pipe 31. Start the chemical cleaning pump 30. When chemically cleaning, the valve on the forward flushing pipe 15 can be opened to increase the flushing intensity on the surface of the membrane disc 7 during cleaning and improve the chemical cleaning effect.

[0038] The use of the present utility model can effectively improve the anti-pollution performance of the membrane module against zinc powder, iron powder and oil substances in the waste water of the skin pass mill. The equipment occupies a small area and is convenient for cleaning and recovery.

[0039] In this embodiment, a membrane module with a filtration accuracy of 20 nm and the membrane disc 7 made of silicon carbide is adopted. This embodiment takes the waste water of the skin pass mill in the cold rolling mill as the treatment object, controls the operating pressure to be 0.20 - 0.25 Mpa, the water production rate to be 90%, the chemical cleaning period of the membrane module to be 3 - 6 months, and the membrane water production flux can stably reach more than 100 L / (m 2 ·h) or more. When the membrane water production flux decays by more than 15%, the membrane water production flux can be effectively restored through chemical cleaning.

[0040] Finally, several points should be noted: First, in the description of this application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. It can be a mechanical connection or an electrical connection, or it can be the communication inside two components. It can be directly connected. "Up", "down", "left", "right", etc. are only used to represent the relative position relationship. When the absolute position of the described object changes, the relative position relationship may change;

[0041] Second: In the attached drawings of the disclosed embodiments of the present utility model, only the structures related to the disclosed embodiments are involved. Other structures can refer to the general design. Without conflict, the same embodiment and different embodiments of the present utility model can be combined with each other;

[0042] Finally: The above description is only the preferred embodiment of the present utility model and is not used to limit the present utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. An ultrafiltration membrane device for treating wastewater from a polishing machine, characterized in that: The invention comprises a membrane assembly, a compressed air backwash assembly, a clean water backwash assembly and a forward flushing assembly; the membrane assembly comprises a membrane shell (1) and a multilayer membrane disc (7) arranged in the membrane shell (1) via a central axis (6), the central axis (6) being connected to a water production port (5); the compressed air backwash assembly comprises a backwash air inlet pipe (19) and an air compressor (22), the air compressor (22) being connected to the water production port (5) via the backwash air inlet pipe (19); the clean water backwash assembly comprises a cleaning water inlet pipe (21) and a cleaning pump (24), the cleaning pump (24) being connected to the water production port (5) via the cleaning water inlet pipe (21); the forward flushing assembly comprises a forward flushing pipe (15).

2. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 1, characterized in that: The membrane assembly further comprises a support (2) and a water distribution pipe (3) and a water outlet (4) arranged on the support (2).

3. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 2, characterized in that: The water distribution pipe (3) is connected to the water inlet pipe (12) and the forward flushing pipe (15).

4. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 3, characterized in that: The water distribution pipe (3) is provided with a branch pipe, which is arranged in sequence between two adjacent membrane discs (7).

5. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 4, characterized in that: The number of branch pipes is one more than the number of membrane discs (7).

6. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 1, characterized in that: The number of membrane discs (7) of the membrane assembly is 10 to 30, and the distance between two membrane discs (7) is 40 to 50 mm.

7. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 4, characterized in that: Small holes are provided on the branch pipe, and the small holes and the membrane disc (7) are symmetrically arranged at an angle of 45° to the vertical direction of the branch pipe.

8. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 1, characterized in that: The membrane disc (7) comprises a support layer (27) and a membrane layer. The membrane layer is double-sided and comprises a transition layer (25) and a membrane filtration layer (26). A guide groove (28) is provided on the support layer (27). The transition layer (25) is located between the support layer (27) and the membrane filtration layer (26). The transition layer (25) is a three-layer structure. The inner layer of the transition layer (25) covers the support layer (27). The guide groove (28) is distributed in a spiral along the center of the membrane disc (7).

9. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 1, characterized in that: The central shaft (6) is provided with a water guide hole, which is in communication with the guide groove (28) of the membrane disc (7).

10. The ultrafiltration membrane device for treating wastewater from a polishing machine according to claim 6, characterized in that: The filtration accuracy of the membrane disc (7) is 5-30 nm.

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