A process and apparatus for making a hollow fiber support membrane

Abstract

The application provides a process and equipment for preparing a hollow fiber support membrane, comprising a pre-prepared core liquid support pipe device, a spinneret, a first coagulation tank and a second cleaning tank, wherein the pre-prepared core liquid support pipe device is connected with the spinneret, the spinneret is connected with the first coagulation tank, and the first coagulation tank is connected with the second cleaning tank; the pre-prepared core liquid support pipe device is sequentially provided with a pre-preparation chamber, a liquid removal chamber and a drying chamber, and a plurality of guide rollers are arranged in the pre-preparation chamber, the liquid removal chamber and the drying chamber. The process for preparing the hollow fiber support membrane introduces support pipe pre-prepared core liquid, and the efficiency of manufacturing the hollow fiber support membrane completely reaches the same production efficiency of NIPS homogeneous hollow fiber membrane, 40-80 m / min, and the thickness uniformity of the hollow fiber support membrane layer can be well controlled, and the hollow fiber support membrane has higher bonding force with the support pipe, reaching >7.8 N.

Description

Technical Field

[0001] This invention belongs to the field of hollow fiber support membranes, and in particular relates to a process and equipment for preparing hollow fiber support membranes. Background Technology

[0002] NIPS (Non-solvent Phase Separation) hollow fiber membrane manufacturing involves coating the outside of the support tube with a membrane-forming solution containing a high-molecular polymer, and it is widely used in the wastewater treatment industry. Currently, because the support tubes in the hollow fiber membrane of the supported membrane are continuously wound on a coil, it is impossible to introduce a dedicated coagulation solution ("core liquid") into the hollow structure as in the homogeneous NIPS hollow fiber membrane preparation process. Therefore, the coating solution must be slowly penetrated from the outside to the inside of the support tube by an external coagulation solution to achieve complete exchange and solidification, thus bonding the coating solution to the support tube. The spinning efficiency is only 15-20 m / min. Because it is a unidirectional replacement, it requires a long time, which not only greatly reduces spinning efficiency but also makes the penetration process of the membrane-forming solution difficult to control. Sometimes, excessive ineffective penetration into the inner layer can lead to a smaller hollow structure or even blockage, affecting the future functionality of the product. Conversely, excessively fast spinning speeds can cause insufficient time for the coating layer to solidify, resulting in membrane deformation, peeling, and irregularities in the inner layer. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the defects in the prior art and propose a process and equipment for preparing hollow fiber supported membranes.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] This invention provides an apparatus for preparing hollow fiber supported membranes, including a pre-prepared core liquid support tube device, a spinneret, a primary coagulation tank, and a secondary cleaning tank. The pre-prepared core liquid support tube device is connected to the spinneret, the spinneret is connected to the primary coagulation tank, and the primary coagulation tank is connected to the secondary cleaning tank.

[0006] The pre-formed core liquid support pipe device is provided with a pre-forming chamber, a liquid removal chamber and a drying chamber in sequence, and each of the pre-forming chamber, the liquid removal chamber and the drying chamber is provided with a number of guide wheels.

[0007] Furthermore, the prefabrication chamber is equipped with a core liquid tank, which contains core liquid; the upper part of the prefabrication chamber is provided with a core liquid inlet, which is connected to a core liquid storage tank through a pipeline; a level gauge is installed on the prefabrication chamber; and a discharge port is provided at the bottom of the prefabrication chamber.

[0008] Furthermore, the upper part of the liquid removal chamber is provided with several cold air purging units, and the top of the liquid removal chamber is provided with several first air inlets, the positions of which correspond to the cold air purging units; the bottom of the liquid removal chamber is provided with a core liquid collection tank; the bottom of the liquid removal chamber is provided with a core liquid collection port, which is connected to the core liquid collection tank; and the top of the liquid removal chamber is also provided with a cold air exhaust port.

[0009] Furthermore, the top of the drying chamber is provided with several second air inlets, and the upper part of the drying chamber is provided with several hot air surface drying units, the positions of which correspond to the second air inlets. An electric heater is provided below the hot air surface drying units. The bottom of the drying chamber is provided with a hot air exhaust port, which is connected to a condenser through a pipe. A water vapor condensation collection port is provided on one side of the drying chamber.

[0010] Furthermore, the guide wheel is connected to the corresponding drive shaft, and the drive shaft is connected to the corresponding motor; both the end of the guide wheel and the drive shaft are provided with helical gears, and the guide wheel is connected to the drive shaft through the meshing of the helical gears; both the end of the output shaft of the motor and the end of the drive shaft are provided with helical gears, and the motor is connected to the drive shaft through the meshing of the helical gears.

[0011] Furthermore, the spinneret is connected to the film-forming liquid material storage tank.

[0012] Furthermore, the blowing temperature of the cold air blowing unit in step (2) is 10-40℃ and the blowing time is 10-200s.

[0013] Furthermore, the blowing temperature of the hot air surface drying unit in step (3) is 60-90℃ and the blowing time is 10-200s.

[0014] The present invention also provides a process for using the aforementioned apparatus for preparing hollow fiber supported membranes, comprising the following steps:

[0015] (1) The support tube enters the prefabrication chamber of the prefabrication core liquid support tube device and is immersed in the core liquid in the core liquid tank by the drive of the guide wheel. The core liquid fills the hollow part of the support tube.

[0016] (2) The support tube filled with core liquid enters the liquid removal chamber, and the cold air blowing unit blows cold air on it to remove the core liquid on the surface of the support tube. The core liquid is collected through the core liquid collection tank.

[0017] (3) The support tube with the surface core liquid removed enters the drying chamber, the hot air surface drying unit blows hot air on it, and the surface of the support tube is dried by the heating of the electric heater. Then the hot air enters the condenser through the hot air exhaust port to recover the hot air.

[0018] (4) The surface-dried support tubes are sequentially fed into the spinneret, the primary coagulation tank and the secondary cleaning tank to obtain a hollow fiber support membrane.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The process for preparing hollow fiber supported membranes described in this invention involves "pre-forming" the core liquid in the "hollow" part of the support tube before it enters the nozzle and contacts the membrane-forming liquid. Simultaneously, the outside and walls of the support tube remain dry. Upon entering the support tube, the material immediately contacts the pre-formed core liquid in the hollow part, allowing it to penetrate the interior. The membrane-forming liquid quickly solidifies and distributes evenly on the inner wall of the hollow support tube, preventing it from solidifying directly on the outer surface and thus avoiding insufficient penetration into the inner wall and affecting adhesion. This process enables the NIPS hollow fiber supported membrane to achieve the same production efficiency as the NIPS homogeneous hollow fiber membrane, while maintaining the same membrane layer and higher adhesion to the support tube as conventional NIPS hollow fiber supported membranes, and ensuring unobstructed flow in the hollow section.

[0021] The process for preparing hollow fiber supported membranes described in this invention introduces a pre-prepared core liquid for the support tube, achieving the same production efficiency as NIPS homogeneous hollow fiber membranes (40-80 m / min). Furthermore, it can effectively control the uniformity of the thickness of the hollow fiber supported membrane layer and provides a higher bonding force with the support tube, reaching >7.8 N. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 This is a schematic diagram of the apparatus for preparing hollow fiber supported membranes according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the pre-formed core liquid support tube device according to an embodiment of the present invention;

[0025] Figure 3 This is a right view of the pre-formed core liquid support tube device according to an embodiment of the present invention;

[0026] Figure 4 is a schematic diagram of the hollow fiber support membrane according to an embodiment of the present invention: 4-A is a cross-section of the hollow fiber support membrane; 4-B is the outer surface of the hollow fiber support membrane; 4-C is the inner surface of the hollow fiber support membrane;

[0027] Figure 5 This is a schematic diagram of the peel test of the film layer adhesion of the hollow fiber supported membrane according to an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Winding reel; 2. Core liquid tank; 3. Core liquid storage tank; 4. Cold air purging unit; 5. Core liquid collection tank; 6. Hot air surface drying unit; 7. Condenser; 8. Spinneret support tube inlet; 9. Spinneret material inlet; 10. Film forming solution material storage tank; 11. Primary coagulation tank; 12. Secondary cleaning tank; 13. Film filament winding reel; 14. Core liquid inlet; 15. Level gauge; 16. Discharge port; 17. First air inlet; 18. Cold air exhaust port; 19. Core liquid collection port; 20. Second air inlet; 21. Electric heater; 22. Hot air exhaust port; 23. Water vapor condensation collection port; 24. Drive shaft; 25. Guide wheel; 26. Motor; 27. Support tube; 28. Spinneret. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] like Figure 1-3 As shown, an apparatus for preparing hollow fiber supported membranes includes a pre-prepared core liquid support tube device, a spinneret, a primary coagulation tank, and a secondary cleaning tank. The pre-prepared core liquid support tube device is connected to the spinneret, the spinneret is connected to the primary coagulation tank, and the primary coagulation tank is connected to the secondary cleaning tank.

[0034] The pre-formed core liquid support tube device is sequentially arranged with a pre-forming chamber, a liquid removal chamber, and a drying chamber, each with several guide rollers inside. The spinneret is connected to the film-forming liquid material storage tank.

[0035] The prefabrication chamber is equipped with a core liquid tank, which contains core liquid; the upper part of the prefabrication chamber is provided with a core liquid inlet, which is connected to a core liquid storage tank through a pipeline; a level gauge is provided on the prefabrication chamber; and a discharge port is provided at the bottom of the prefabrication chamber.

[0036] The upper part of the liquid removal chamber is provided with three cold air purging units, and the top of the liquid removal chamber is provided with three first air inlets, the positions of which correspond to the cold air purging units; the bottom of the liquid removal chamber is provided with a core liquid collection tank; the bottom of the liquid removal chamber is provided with a core liquid collection port, which is connected to the core liquid collection tank; the top of the liquid removal chamber is also provided with a cold air exhaust port.

[0037] The drying chamber has two second air inlets at the top and two hot air surface drying units at the top, with the positions of the hot air surface drying units corresponding to the second air inlets. An electric heater is located below each hot air surface drying unit. A hot air exhaust port is located at the bottom of the drying chamber and is connected to a condenser via a pipe. A water vapor condensation collection port is located on one side of the drying chamber. Both the hot air surface drying units and the cold air purging units are automatic wind-powered dryers.

[0038] The guide wheel is connected to the corresponding drive shaft, and the drive shaft is connected to the corresponding motor. Both the end of the guide wheel and the end of the drive shaft are provided with helical gears, and the guide wheel is connected to the drive shaft through the meshing of the helical gears. Both the end of the output shaft of the motor and the end of the drive shaft are provided with helical gears, and the motor is connected to the drive shaft through the meshing of the helical gears.

[0039] A process using the aforementioned apparatus for preparing hollow fiber supported membranes includes the following steps:

[0040] (1) The support tube enters the prefabrication chamber of the prefabrication core liquid support tube device and is immersed in the core liquid in the core liquid tank by the drive of the guide wheel. The core liquid fills the hollow part of the support tube.

[0041] (2) The support tube filled with core liquid enters the liquid removal chamber, and the cold air blowing unit blows cold air on it to remove the core liquid on the surface of the support tube. The core liquid is collected through the core liquid collection tank.

[0042] (3) The support tube with the surface core liquid removed enters the drying chamber, the hot air surface drying unit blows hot air on it, and the surface of the support tube is dried by the heating of the electric heater. Then the hot air enters the condenser through the hot air exhaust port to recover the hot air.

[0043] (4) The surface-dried support tubes are sequentially fed into the spinneret, the primary coagulation tank and the secondary cleaning tank to obtain a hollow fiber support membrane.

[0044] like Figure 1-3As shown, in the entire spinning process, the support tube coiled on the spinning spool is first moved to the pre-forming chamber of the pre-forming core liquid support tube device, where the inner and outer surfaces of the support tube are completely wetted and the hollow part inside the tube is completely filled with core liquid. The pre-forming chamber is connected to the core liquid storage tank to maintain the liquid level in the core liquid tank at a certain height. The support tube with core liquid is then quickly moved into the dehydration chamber, where cold air blows away a large amount of excess core liquid from the outer surface of the support tube. The core liquid collection tank is connected to the collection tank for residual core liquid, where the core liquid removed from the outer surface of the support tube is collected for recycling. The support tube with the core liquid removed from its outer surface is then... The support tubes are rapidly transferred to a drying chamber where hot air dries their outer surface, leaving no moisture. The hot air then enters a condenser for recycling. The hollow support tubes, now with core liquid and a dry outer surface, are then rapidly transferred to the spinneret support tube inlet of the spinning spinneret. Simultaneously, the film-forming liquid from the material storage tank enters the spinneret nozzle material inlet. The support tubes and film-forming liquid meet in the spinneret, coating the support tubes and penetrating their inner walls before contacting the core liquid. The fresh, unformed hollow fiber support membrane, coated on the support tubes, then passes through an air section and directly enters the primary coagulation tank. The fresh, unformed hollow fiber support membrane coats the inner and outer surfaces of the support tube coating layer and rapidly solidifies under the combined action of the external coagulation liquid and the core liquid in the support tube. It then enters a secondary cleaning tank to further solidify the formed hollow fiber support membrane and remove residual solvent from the filaments. Finally, the finished product filaments are wound onto a filament winding wheel to obtain the hollow fiber support membrane.

[0045] The pre-formed core liquid support tube device consists of three parts: a pre-forming chamber, a descaling chamber, and a drying chamber. The core liquid inlet is connected to the core liquid storage tank. The support tube enters the core liquid tank through guide rollers. In this section, the core liquid level is controlled by a level gauge, and upper and lower conveying guide rollers are installed to ensure that the core liquid fills the inner cavity of the support tube. The outlet is used for material discharge and cleaning during material change. The support tube with pre-formed core liquid on its outer surface enters the descaling chamber to remove the solution from the outer surface of the support tube. The descaling chamber is equipped with three first air inlets to blow away the liquid on the outer surface and collect it for reuse through the core liquid collection port. A cold air exhaust port is used for ventilation. In the drying chamber, there are two second air inlets and an electric heater. The generated hot air dries the wet outer surface of the pre-formed core liquid support tube, which then enters the next spinning process. The drying chamber is equipped with a water vapor condensation collection port and a hot air exhaust port.

[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] Example 1

[0048] Taking polyvinylidene fluoride (PVDF) film-forming solution as an example:

[0049] A process for preparing hollow fiber supported membranes involves firstly, support tubes with OD 1.85mm and ID 1.10mm diameters wound on an I-shaped winding spool are introduced into a pre-prepared core liquid support tube device. The core liquid tank contains a 70% dimethylamine acetate (DMAc) aqueous solution. The support tubes are moved into the core liquid tank, filling their hollow portions with the core liquid. They are then moved to a removal chamber where excess core liquid is removed from the outer surface of the support tubes by cold air. The temperature is controlled at 20°C for 40 seconds. The core liquid removed from the core liquid tank is automatically replenished by a core liquid storage tank. The core liquid tank is connected to a core liquid collection tank via a core liquid collection port to collect excess core liquid from the outer surface of the support tubes. After a large amount of outer surface core liquid has been removed, the support tubes enter a drying chamber where the temperature is controlled at 80°C for 40 seconds to remove the pre-prepared core liquid. The outer surface of the core-forming liquid support tube is dried, and the evaporated water vapor containing DMAC is recovered by the condenser. The support tube with the pre-formed core liquid on its dried outer surface enters the spinneret through the spinneret support tube inlet, where it merges with the PVDF film-forming liquid entering from the spinneret material inlet. This mixture coats the pre-formed core liquid support tube and penetrates into the hollow inner layer of the support tube, exchanging with the pre-formed core liquid in the hollow part to form an inner film layer. Simultaneously, it quickly enters the primary coagulation tank, where the outer coating layer further exchanges with the outer coagulation liquid, completely solidifying the fresh, uncoated coating film layer on both the inner and outer surfaces. Finally, the film-forming solvent and the remaining pre-formed core liquid in the hollow part are removed in the secondary cleaning tank, cleaning the PVDF hollow fiber support film. The final hollow fiber support film is then obtained on the winding wheel.

[0050] The spinning rate was set at 60 m / min. The resulting membrane product (Figure 4) had an outer diameter of 2.02 mm and a membrane thickness of 90-100 μm. After treatment with a dry protectant, the dried membrane fibers were subjected to a peel test using standard Scotch tape with a 7.8 N adhesion strength; no peeling occurred. Figure 5 ).

[0051] The process and equipment for preparing hollow fiber supported membranes described in this invention significantly improve spinning production efficiency. Compared with existing hollow fiber membrane manufacturing processes, the spinning speed is increased from 15-25 m / min to over 60 m / min. Furthermore, the thickness of the inner and outer membrane layers is uniform and controllable, preventing a large amount of ineffective membrane-forming liquid from seeping into the hollow support tube, causing a reduction in inner diameter and material waste. While the thicker membrane layer also increases liquid filtration resistance, the uniform inner and outer coating ensures excellent adhesion between the membrane layer and the support tube, preventing membrane peeling.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing hollow fiber supported membranes, characterized in that: Includes the following steps: (1) The support tube enters the prefabrication chamber of the prefabrication core liquid support tube device and is immersed in the core liquid in the core liquid tank by the drive of the guide wheel. The core liquid fills the hollow part of the support tube. The core liquid is a 70% dimethylamine aqueous solution. (2) The support tube filled with core liquid enters the liquid removal chamber, and the cold air blowing unit blows cold air on it to remove the core liquid on the surface of the support tube. The core liquid is collected through the core liquid collection tank. (3) The support tube with the surface core liquid removed enters the drying chamber, the hot air surface drying unit blows hot air on it, and the surface of the support tube is dried by the electric heater. Then the hot air enters the condenser through the hot air exhaust port to recover the hot air. (4) The surface-dried support tubes are sequentially fed into the spinneret, the primary coagulation tank and the secondary cleaning tank to obtain a hollow fiber support membrane; The blowing temperature of the cold air blowing unit in step (2) is 10-40℃ and the blowing time is 10-200 s; The blowing temperature of the hot air surface drying unit in step (3) is 60-90℃ and the time is 10-200 s.

2. The process for preparing hollow fiber supported membranes according to claim 1, characterized in that: The equipment used in the process includes a pre-formed core liquid support tube device, a spinneret, a primary coagulation tank, and a secondary cleaning tank. The pre-formed core liquid support tube device is connected to the spinneret, the spinneret is connected to the primary coagulation tank, and the primary coagulation tank is connected to the secondary cleaning tank. The pre-formed core liquid support pipe device is provided with a pre-forming chamber, a liquid removal chamber and a drying chamber in sequence, and the interior of the pre-forming chamber, the liquid removal chamber and the drying chamber are each provided with a number of guide wheels; The prefabrication chamber is equipped with a core liquid tank, which contains core liquid; the upper part of the prefabrication chamber is equipped with a core liquid inlet, which is connected to a core liquid storage tank through a pipeline. The upper part of the liquid removal chamber is provided with several cold air purging units, and the top of the liquid removal chamber is provided with several first air inlets, the positions of the first air inlets corresponding to the cold air purging units. The top of the drying chamber is provided with several second air inlets, and the upper part of the drying chamber is provided with several hot air surface drying units. The positions of the hot air surface drying units correspond to the second air inlets, and an electric heater is provided below the hot air surface drying units.

3. The process for preparing hollow fiber supported membranes according to claim 1, characterized in that: The prefabrication chamber is equipped with a level gauge; the bottom of the prefabrication chamber is provided with a discharge port.

4. The process for preparing hollow fiber supported membranes according to claim 2, characterized in that: The bottom of the liquid removal chamber is provided with a core liquid collection tank; the bottom of the liquid removal chamber is provided with a core liquid collection port, which is connected to the core liquid collection tank; the top of the liquid removal chamber is also provided with a cold air exhaust port.

5. The process for preparing hollow fiber supported membranes according to claim 2, characterized in that: The bottom of the drying chamber is provided with a hot air exhaust port, which is connected to the condenser through a pipeline; a water vapor condensation collection port is provided on one side of the drying chamber.

6. The process for preparing a hollow fiber supported membrane according to claim 2, characterized in that: The guide wheel is connected to the corresponding drive shaft, and the drive shaft is connected to the corresponding motor. Helical gears are provided on both the end of the guide wheel and the drive shaft, and the guide wheel is connected to the drive shaft through the meshing of the helical gears. Helical gears are provided on both the end of the output shaft of the motor and the end of the drive shaft, and the motor is connected to the drive shaft through the meshing of the helical gears.

7. The process for preparing a hollow fiber supported membrane according to claim 1, characterized in that: The spinneret is connected to the film-forming liquid material storage tank.

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