Method and apparatus for repairing defects on the inside of a hollow fiber membrane

Abstract

The application discloses a hollow fiber membrane inner side defect repairing method and device, and the hollow fiber membrane wire to be repaired is guided into a crosslinking bath through a roller and collected on a wire collecting wheel; after the hollow fiber membrane wire on the wire collecting wheel is assembled, centrifugally filled with glue and cut in section, a hollow fiber membrane assembly is formed; an oligomer to be crosslinked is filled into the inner side of the membrane assembly, after a circulating filling step, air blowing, leakage checking and programmed temperature rising processes are carried out, and the repairing of the defect is completed. The application fills the oligomer to be crosslinked into the inner side channel of the hollow fiber gas separation membrane assembly which has active crosslinking sites, so that the interface polymerization and crosslinking of the crosslinking agent bath oligomer occur in the dense layer of the inner side of the membrane, the defect repairing of the dense layer of the inner side of the hollow fiber is completed, the separation performance of the hollow fiber gas separation membrane is improved, and the application has important significance for producing the hollow fiber gas separation membrane assembly with high performance.

Description

Technical Field

[0001] This invention belongs to the field of gas separation membrane technology, specifically relating to a method and apparatus for repairing defects on the inner side of a hollow fiber membrane. Background Technology

[0002] Gas separation membranes can be used in fields such as CO2 capture from natural gas / associated gas, hydrocarbon recovery, nitrogen / oxygen enrichment from air separation, hydrogen separation, and helium extraction. Compared to spiral wound membranes and flat sheet membranes, hollow fiber membranes have a higher packing density and a larger effective separation area per unit volume, effectively reducing the size of the membrane separation device. Hollow fiber membranes generally consist of two parts: a dense skin layer and a mechanical support layer. The structure and integrity of the dense skin layer are key to determining the separation selectivity and throughput of the hollow fiber membrane.

[0003] During the formation of hollow fiber membranes, the continuous exchange of substances between the inside and outside of the membrane during phase separation leads to defects in the dense skin layer. These defects need to be repaired to ensure the gas separation performance of the membrane. Hollow fiber membranes with the dense skin layer located on the inner circular surface are called hollow fiber inner membranes. Compared to hollow fiber membranes with the dense skin layer located on the outer surface, the space for defect repair is limited, and the repair of defects is more difficult, which seriously affects the application of hollow fiber inner membranes in the field of gas separation.

[0004] Typically, defects in hollow fiber membranes are repaired using an impregnation method, as described in patent CN 114746166A. However, this simple impregnation method is difficult to apply to repairing defects in the inner membrane of hollow fibers. Patent CN 115105965A describes a method of filling the inner and outer sides of the membrane module separately and repairing the dense skin layer in situ through interfacial polymerization. However, this method does not consider the impact of residual filling liquid in the membrane on the membrane structure and performance, and is not conducive to continuous operation and large-scale production.

[0005] Therefore, developing a process and device for repairing defects on the inner side of hollow fiber membranes is crucial for improving the performance and production efficiency of hollow fiber inner membranes. Summary of the Invention

[0006] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a method and apparatus for repairing defects on the inner side of hollow fiber membranes.

[0007] This invention is achieved through the following technical solution:

[0008] A method for repairing defects on the inner side of a hollow fiber membrane includes the following steps:

[0009] S1. The hollow fiber membrane filament to be repaired is introduced into the crosslinking bath through a roller, and after traveling in the crosslinking bath, it is wound up on the take-up roller.

[0010] S2. Remove the hollow fiber membrane filaments wound on the take-up roller, assemble them with the metal cylinder, and then seal both ends of the hollow fiber membrane filaments to form a hollow fiber membrane assembly.

[0011] S3. Fill the inner channel with the filling liquid from the inlet of the inner channel of the hollow fiber membrane module and let it flow out from the outlet of the inner channel at the other end.

[0012] S4. After filling is completed, compressed air is introduced into the inlet of the inner channel of the hollow fiber membrane module to purge the remaining filling liquid out of the inner channel of the hollow fiber membrane. The purging ends after the solvent sensor at the outlet of the inner channel of the hollow fiber membrane module passes the test.

[0013] S5. After purging, the hollow fiber membrane module is heated to complete the repair of defects on the inner side of the hollow fiber membrane.

[0014] In the above technical solution, the crosslinking bath includes a crosslinking agent and a solvent; the crosslinking agent is any one of acrylate crosslinking agents, silane coupling agents, organic peroxide crosslinking agents, diamine crosslinking agents, carboxylic acid crosslinking agents, or acid anhydride crosslinking agents; the solvent is at least one of water, methanol, ethanol, isopropanol, butanediol, n-hexane, petroleum ether, methyl isobutyl ketone, toluene, dichloromethane, or n-heptane; the mass fraction of the crosslinking agent in the crosslinking bath is 0.05% to 10%.

[0015] In the above technical solution, the temperature of the crosslinking bath is 20 ℃ ~ 50 ℃; the travel length in the crosslinking bath is 2m ~ 500m; and the travel speed is 2 m / min ~ 100 m / min.

[0016] In the above technical solution, the hollow fiber membrane assembly includes an inner and outer hollow fiber membrane bundle and a metal cylinder. The hollow fiber membrane bundle is a cylindrical structure composed of multiple hollow fiber membrane filaments. The gap between the outer wall of the hollow fiber membrane bundle and the metal cylinder is the outer channel, and the through holes of the hollow fiber membrane filaments are the inner channel. The two ends of the metal cylinder are respectively provided with an inner channel inlet and an inner channel outlet. The two ends of the outer circumferential wall of the metal cylinder are respectively provided with an outer channel inlet and an outer channel outlet. The inner channel inlet and inner channel outlet are connected to the inner channel; the outer channel inlet and outer channel outlet are connected to the outer channel.

[0017] In the above technical solution, the filling liquid includes an oligomer and a solvent; the oligomer is any one of oligoacrylic acid, oligopolyvinyl alcohol, oligocellulose, oligosiloxane, oligopolyurethane, oligoamide or oligolactic acid; the number average molecular weight of the oligomer is between 100 and 50,000.

[0018] The oligomers described in this application are polymers with an index-average molecular weight between 100 and 50,000 as required by this application; oligoacrylic acid is polyacrylic acid with an index-average molecular weight between 100 and 50,000; oligopolyvinyl alcohol is polyvinyl alcohol with an index-average molecular weight between 100 and 50,000; oligocellulose is polycellulose with an index-average molecular weight between 100 and 50,000; oligosiloxane is polysiloxane with an index-average molecular weight between 100 and 50,000; oligopolyurethane is polyurethane with an index-average molecular weight between 100 and 50,000; oligoamide is polyamide with an index-average molecular weight between 100 and 50,000; oligolactic acid is polylactic acid with an index-average molecular weight between 100 and 50,000; all oligomers can be commercially available products, and polymer products with molecular weights that meet the requirements of this application are used as oligomers in this application.

[0019] In the above technical solution, the solvent is at least one of water, methanol, ethanol, isopropanol, butanediol, n-hexane, petroleum ether, methyl isobutyl ketone, toluene, dichloromethane, or n-heptane; the mass concentration of the oligomer in the filling liquid is 0.1% to 30%.

[0020] In the above technical solution, when the filling liquid flows in the inner channel of the hollow fiber membrane module, the outer channel of the hollow fiber membrane module is subjected to vacuum treatment.

[0021] In the above technical solution, the temperature of the compressed air is 10 ℃ ~ 60 ℃; the standard for the solvent sensor to pass detection is that the concentration of solvent in the purge outlet airflow is below 1000 ppm.

[0022] In the above technical solution, the temperature of the heat treatment is 30 ℃ ~ 80 ℃, and the duration of the heat treatment is 1 h ~ 24 h.

[0023] A hollow fiber membrane inner defect repair device for the aforementioned defect repair method includes a filling liquid storage tank, a centrifugal pump, a filter, a vacuum pump, a purging mechanism, and at least one workpiece support; the hollow fiber membrane assembly is placed on the workpiece support;

[0024] The outlet of the filling liquid storage tank is connected to the inlet of the inner channel of the hollow fiber membrane module through a pipeline, and a centrifugal pump and a filter are sequentially installed on the pipeline according to the liquid flow direction; the inlet of the filling liquid storage tank is connected to the outlet of the inner channel of the hollow fiber membrane module through a pipeline.

[0025] The vacuum pump is connected to the outer channel inlet and / or outer channel outlet of the hollow fiber membrane module;

[0026] The purging mechanism includes a gas cylinder and a solvent sensor; the gas cylinder is connected to the inlet of the inner channel of the hollow fiber membrane module through a pipeline; the solvent sensor is installed on the pipeline at the outlet of the inner channel of the hollow fiber membrane module.

[0027] In the above technical solution, when multiple hollow fiber membrane modules are repaired at the same time, the multiple hollow fiber membrane modules are connected in series or in parallel; the inlet and outlet of the filling liquid storage tank and the multiple hollow fiber membrane modules form a loop.

[0028] The beneficial effects of this invention are:

[0029] This invention provides a method and apparatus for repairing defects on the inner side of hollow fiber membranes. By combining online impregnation of crosslinking agents with internal filling of oligomers, a device for repairing defects on the inner side of hollow fiber membranes is developed. This solves the problem that traditional impregnation and crosslinking methods cannot repair defects in the dense inner layer of the membrane, and minimizes the impact of the defect repair material on the membrane separation performance. Through repairing defects on the inner side of hollow fibers, the separation performance of hollow fiber gas separation membranes is greatly improved. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the device of the present invention;

[0031] Figure 2 This is a SEM image of the dense layer of the hollow fiber gas separation membrane without internal defect repair in Embodiment 1 of the present invention;

[0032] Figure 3 This is a SEM image of the dense layer of the hollow fiber gas separation membrane after internal defect repair in Embodiment 1 of the present invention.

[0033] in:

[0034] 1. Filling liquid storage tank; 2. Centrifugal pump; 3. Filter; 4. Hollow fiber membrane module; 5. Gas cylinder.

[0035] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] A method for repairing defects on the inner side of a hollow fiber membrane includes the following steps:

[0038] S1. The hollow fiber membrane filament to be repaired is introduced into the crosslinking bath through a roller, and after traveling a certain length in the crosslinking bath, it is wound up onto the take-up roller.

[0039] The crosslinking bath in step S1 includes a crosslinking agent and a solvent; the crosslinking agent is any one of acrylate crosslinking agents, silane coupling agents, organic peroxide crosslinking agents, diamine crosslinking agents, carboxylic acid crosslinking agents, or acid anhydride crosslinking agents; the solvent is at least one of water, methanol, ethanol, isopropanol, butanediol, n-hexane, petroleum ether, methyl isobutyl ketone, toluene, dichloromethane, or n-heptane.

[0040] The mass fraction of the crosslinking agent in the crosslinking bath in step S1 is 0.05% to 10%.

[0041] The temperature of the crosslinking bath in step S1 is 20 ℃ ~ 50 ℃;

[0042] The crosslinking bath in step S1 is placed in a crosslinking tank, and the temperature of the crosslinking tank can be controlled.

[0043] In step S1, the travel length in the crosslinking bath is 2m to 500m; the travel speed is 2m / min to 100m / min.

[0044] S2. Remove the hollow fiber membrane filaments wound on the take-up roller, cut them as needed, combine multiple hollow fiber membrane filaments into a hollow fiber membrane filament bundle, then assemble the hollow fiber membrane filament bundle with the metal cylinder, and then cut the hollow fiber membrane filament bundle at the cross section and seal both ends to form a hollow fiber membrane assembly.

[0045] The hollow fiber membrane bundle is a cylinder composed of multiple hollow fiber membrane filaments;

[0046] The assembly involves either filling the hollow fiber membrane bundle into a metal cylinder or placing the hollow fiber membrane bundle on a fixed shaft and then directly filling it into a metal cylinder.

[0047] The cutting involves cutting off the excess membrane filaments at both ends of the metal cylinder;

[0048] After the hollow fiber membrane bundle is assembled, the two ends are sealed by natural epoxy resin casting or by centrifugal spinning.

[0049] The gap between the outer wall of the hollow fiber membrane bundle and the metal cylinder in the hollow fiber membrane module is the outer channel (shell side), and the through holes of the hollow fiber membrane filaments are the inner channel (inner cavity); the two end faces of the hollow fiber membrane module are respectively provided with an inner channel inlet and an inner channel outlet, and the two ends of the outer circumferential wall of the hollow fiber membrane module that are opposite are respectively provided with an outer channel inlet and an outer channel outlet, the inner channel inlet and inner channel outlet are connected to the inner channel; the outer channel inlet and outer channel outlet are connected to the outer channel;

[0050] S3. Fill the inner channel with the filling liquid from the inlet of the inner channel of the hollow fiber membrane module and let it flow out from the outlet of the inner channel at the other end.

[0051] The filling process requires the filling liquid in the hollow fiber membrane module to be replaced at least three times.

[0052] The circulation flow rate of the filling liquid should be limited to prevent the internal channels of the hollow fiber membrane from bursting; in most cases, the inlet pressure on the filling side is recommended to be between 5 kPa and 200 kPa.

[0053] The filling liquid in step S3 includes oligomers and solvents;

[0054] The mass concentration of the oligomer in the filling liquid is 0.1% to 30%, preferably 1% to 15%, and more preferably 3% to 10%.

[0055] The oligomer is any one of oligoacrylic acid, oligopolyvinyl alcohol, oligocellulose, oligosiloxane, oligopolyurethane, oligoamide or oligolactic acid;

[0056] The number-average molecular weight of the oligomer is between 100 and 50,000, preferably between 200 and 2,000;

[0057] The solvent is at least one selected from water, methanol, ethanol, isopropanol, butanediol, n-hexane, petroleum ether, methyl isobutyl ketone, toluene, dichloromethane, or n-heptane.

[0058] In step S3, when the filling liquid flows in the inner channel of the hollow fiber membrane module, the outer channel of the hollow fiber membrane module is vacuumed (gauge pressure below -0.05MPa). The simultaneous vacuuming of the outer channel facilitates the rapid evaporation of the solvent in the filling liquid and promotes the adhesion of the oligomer to the inner surface of the hollow fiber membrane.

[0059] S4. After filling is completed, compressed air is introduced into the inlet of the inner channel of the hollow fiber membrane module to purge the remaining filling liquid out of the inner channel of the hollow fiber membrane. The purging ends after the solvent sensor at the outlet of the inner channel of the hollow fiber membrane module passes the test.

[0060] The temperature of the compressed air is 10 ℃ ~ 60 ℃, more preferably 40 ℃ ~ 50 ℃; controlling the temperature of the compressed air accelerates solvent evaporation while promoting cross-linking of oligomers and cross-linking agents at the interface of the dense layer inside the hollow fiber membrane.

[0061] The pressure of the compressed air should not cause mechanical damage to the hollow fiber membrane;

[0062] The standard for the solvent sensor to pass the test is that the concentration of solvent in the purge outlet gas flow is below 1000 ppm;

[0063] S5. After purging, the hollow fiber membrane module is heated to complete the repair process of defects on the inner side of the hollow fiber membrane.

[0064] The heat treatment temperature is 30 ℃ ~ 80 ℃, preferably 40 ℃ ~ 60 ℃, and the heat treatment duration is 1 h ~ 24 h.

[0065] The methods for preparing the repaired hollow fiber membrane fibers in Examples 1 and 2 below are based on the method disclosed in Patent 202311752901.1 or the method disclosed in Patent CN116943460B. However, hollow fiber membrane fibers with a permeable internal structure can all be repaired using the method described in this application. The gas separation selectivity of the repaired hollow fiber membrane fiber will be affected by the original preparation method and the original structure of the hollow fiber membrane fiber. However, after repair using the method described in this application, the gas separation selectivity is significantly improved.

[0066] like Figure 1 As shown, a hollow fiber membrane inner defect repair device includes a filling liquid storage tank 1, a centrifugal pump 2, a filter 3, a vacuum pump, a purging mechanism, and at least one workpiece support; the hollow fiber membrane assembly 4 is placed on the workpiece support;

[0067] The outlet of the filling liquid storage tank 1 is connected to the inlet of the inner channel of the hollow fiber membrane module 4 through a pipeline, and a centrifugal pump 2, a filter 3 and an air bubble remover are installed in sequence along the liquid flow direction on the pipeline; the inlet of the filling liquid storage tank 1 is connected to the outlet of the inner channel of the hollow fiber membrane module 4 through a pipeline.

[0068] The inlet of the filling liquid storage tank 1 is also connected to the filling liquid addition pipeline.

[0069] When multiple hollow fiber membrane modules 4 are repaired at the same time, the multiple hollow fiber membrane modules 4 are connected in series or in parallel; the inlet and outlet of the filling liquid storage tank 1 and the multiple hollow fiber membrane modules 4 form a loop.

[0070] The centrifugal pump 2 should have a metering function;

[0071] The filter 3 is designed to effectively intercept self-polymerized oligomers; the filter 3 includes, but is not limited to, metal filter screens, nylon filter screens, filter cylinders formed by rolling up filter screens, and multi-layer filter screens formed by stacking them.

[0072] The vacuum pump is connected to the outer channel inlet and / or outer channel outlet of the hollow fiber membrane module 4 to achieve vacuuming of the outer channel.

[0073] The purging mechanism includes a gas cylinder 5 and a solvent sensor; the gas cylinder 5 is connected to the inlet of the inner channel of the hollow fiber membrane module 4 via a pipeline; the solvent sensor is installed on the pipeline at the outlet of the inner channel of the hollow fiber membrane module 4 to determine whether purging is complete. The solvent sensor is selected based on the composition of the solvent in the filling liquid.

[0074] The hollow fiber membrane inner defect repair device also includes a programmed heating device, which heats the hollow fiber membrane module.

[0075] Example 1

[0076] A method for repairing defects on the inner side of a hollow fiber membrane includes the following steps:

[0077] S1. The hollow fiber membrane filament to be repaired is introduced into the crosslinking bath through a roller at a speed of 15 m / min, and after traveling a certain length in the crosslinking bath, it is wound up on the take-up roller.

[0078] The travel length in the crosslinking bath is 100 m. The crosslinking bath is a petroleum ether solution of 2,3-toluenediamine with a mass fraction of 10%. The crosslinking bath temperature is 20 °C.

[0079] S2. After the membrane fibers that have passed through the cross-linking bath and are collected on the take-up wheel are cut, they are axially and parallelly packed into a metal cylinder with an inner diameter of 15 mm (the membrane fibers form a bundle of hollow fiber membrane fibers). The epoxy resin at both ends is filled between the membrane fibers using a centrifuge to form a hollow fiber membrane module.

[0080] S3. Install a hollow fiber membrane module on the workpiece support of the hollow fiber membrane inner defect repair device, and select an aqueous solution of oligoacrylic acid with a mass fraction of 10% as the filling liquid. The number average molecular weight of oligoacrylic acid is about 800 and the PDI is about 1.8.

[0081] PDI stands for Polymer Dispersion Index, which describes the molecular weight distribution of a polymer, i.e., the ratio of weight-average molecular weight to number-average molecular weight. It is also called the polydispersion index. A value greater than 1 indicates a wider molecular weight distribution, while a smaller value indicates a more uniform distribution.

[0082] S4. The above filling liquid is filled into the inner channel of the component at a circulation rate of 50 mL / min. During filling, the outer channel of the component is evacuated.

[0083] S5. After filling, introduce compressed air at 0.2 MPa and 50 ℃ into the inner port of the hollow fiber membrane module and purge for 10 minutes, 3 times.

[0084] S6. After purging, the hollow fiber membrane module is heat-treated at a temperature of 40°C for 1 hour to complete the repair process of defects on the inner side of the hollow fiber membrane.

[0085] Before defect repair, the membrane fiber in Example 1 exhibited a CO2 flux of 63.35 ± 4.91 GPU at 35 °C and 0.5 MPa, and a CO2 / CH4 selectivity of 2.57 ± 0.49. Its inner dense layer structure is shown in the attached figure. Figure 2 As shown; after defect compensation, its CO2 flux at 35 ℃ and 0.5 MPa is 33.05±3.62 GPU, and its CO2 / CH4 selectivity is 30.09±1.87. Its dense layer structure is shown in the attached figure. Figure 3 As shown.

[0086] Example 2

[0087] A method for repairing defects on the inner side of a hollow fiber membrane includes the following steps:

[0088] S1. The hollow fiber membrane filament to be repaired is introduced into the crosslinking bath through a roller at a speed of 20m / min, and after traveling a certain length in the crosslinking bath, it is wound up on the take-up roller.

[0089] The travel length in the crosslinking bath is 50 m. The crosslinking bath is an ethanol solution of vinyltriethoxysilane with a mass fraction of 5% and the crosslinking bath temperature is 30 ℃.

[0090] S2. After the membrane fibers that have passed through the cross-linking bath and are collected on the take-up wheel are cut, they are filled in parallel into a metal cylinder with an inner diameter of 50 mm. The epoxy resin at both ends is then filled between the membrane fibers using a centrifuge to form a hollow fiber membrane module.

[0091] S3. Connect the two hollow fiber membrane modules in series and install them on the workpiece support of the device. Select a petroleum ether solution of oligopolysiloxane with a mass fraction of 10% as the filling liquid. The number average molecular weight of oligoacrylic acid is about 1500 and the PDI is about 1.3.

[0092] S4. The above filling liquid is filled into the inner channel of the component at a circulation rate of 200 mL / min. During filling, the outer channel of the component is evacuated.

[0093] S5. After filling, introduce compressed air at 0.2 MPa and 40 ℃ into the inner port of the hollow fiber membrane module and purge for 20 min, 3 times.

[0094] S6. After purging, the membrane module is heat-treated at a equilibrium temperature of 60 ℃ for 2 h to complete the repair process of defects on the inner side of the hollow fiber membrane.

[0095] Before defect compensation, the membrane fiber in Example 2 had a CO2 flux of 81.98±10.77 GPU and a CO2 / CH4 selectivity of 11.24±0.35 at 35 °C and 0.5 MPa. After defect compensation, its CO2 flux at 35 °C and 0.5 MPa was 68.38±9.72 GPU and its CO2 / CH4 selectivity was 41.17±0.70.

[0096] This invention introduces a small molecule crosslinking agent into the pore structure of a hollow fiber membrane through online impregnation; through component preparation and coating liquid filling, the selective permeability of the gas separation membrane's dense layer to the polymer is utilized, causing oligomers to aggregate on the surface of the inner dense layer membrane and crosslink in situ with the crosslinking agent, thereby repairing defects in the dense layer. This effectively repairs defects in the hollow fiber membrane's dense layer, resulting in higher gas selectivity performance of the hollow fiber membrane.

[0097] The hollow fiber membrane described in this application is a hollow fiber gas separation membrane.

[0098] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for repairing defects on the inner side of a hollow fiber membrane, characterized in that: Includes the following steps: S1. The hollow fiber membrane filament to be repaired is introduced into the crosslinking bath through a roller, and after traveling in the crosslinking bath, it is wound up on the take-up roller. S2. Remove the hollow fiber membrane filaments wound on the take-up roller, assemble them with the metal cylinder, and then seal both ends of the hollow fiber membrane filaments to form a hollow fiber membrane assembly. S3. Fill the inner channel with the filling liquid from the inlet of the inner channel of the hollow fiber membrane module and let it flow out from the outlet of the inner channel at the other end. The filling solution comprises an oligomer and a solvent; the oligomer is any one of oligoacrylic acid, oligopolyvinyl alcohol, oligocellulose, oligosiloxane, oligopolyurethane, oligoamide, or oligolactic acid; the number average molecular weight of the oligomer is between 100 and 50,000; the solvent is at least one of water, methanol, ethanol, isopropanol, butanediol, n-hexane, petroleum ether, methyl isobutyl ketone, toluene, dichloromethane, or n-heptane; the mass concentration of the oligomer in the filling solution is 0.1% to 30%. S4. After filling is completed, compressed air is introduced into the inlet of the inner channel of the hollow fiber membrane module to purge the remaining filling liquid out of the inner channel of the hollow fiber membrane. The purging ends after the solvent sensor at the outlet of the inner channel of the hollow fiber membrane module passes the test. S5. After purging, the hollow fiber membrane module is heated to complete the repair of defects on the inner side of the hollow fiber membrane.

2. The method for repairing defects on the inner side of a hollow fiber membrane according to claim 1, characterized in that: The crosslinking bath includes a crosslinking agent and a solvent; the crosslinking agent is any one of acrylate crosslinking agents, silane coupling agents, organic peroxide crosslinking agents, diamine crosslinking agents, carboxylic acid crosslinking agents, or acid anhydride crosslinking agents; the solvent is at least one of water, methanol, ethanol, isopropanol, butanediol, n-hexane, petroleum ether, methyl isobutyl ketone, toluene, dichloromethane, or n-heptane; the mass fraction of the crosslinking agent in the crosslinking bath is 0.05% to 10%.

3. The method for repairing defects on the inner side of a hollow fiber membrane according to claim 1, characterized in that: The temperature of the crosslinking bath is 20 ℃ ~ 50 ℃; the travel length in the crosslinking bath is 2m ~ 500m; and the travel speed is 2 m / min ~ 100 m / min.

4. The method for repairing defects on the inner side of a hollow fiber membrane according to claim 1, characterized in that: The hollow fiber membrane assembly includes an inner and outer hollow fiber membrane bundle and a metal cylinder. The hollow fiber membrane bundle is a cylindrical structure composed of multiple hollow fiber membrane filaments. The gap between the outer wall of the hollow fiber membrane bundle and the metal cylinder is the outer channel, and the through holes of the hollow fiber membrane filaments are the inner channel. The two ends of the metal cylinder are respectively provided with an inner channel inlet and an inner channel outlet. The two ends of the outer circumferential wall of the metal cylinder are respectively provided with an outer channel inlet and an outer channel outlet. The inner channel inlet and inner channel outlet are connected to the inner channel; the outer channel inlet and outer channel outlet are connected to the outer channel.

5. The method for repairing defects on the inner side of a hollow fiber membrane according to claim 1, characterized in that: When the filling liquid flows in the inner channel of the hollow fiber membrane module, the outer channel of the hollow fiber membrane module is subjected to vacuum treatment.

6. The method for repairing defects on the inner side of a hollow fiber membrane according to claim 1, characterized in that: The temperature of the compressed air is 10 ℃ ~ 60 ℃; the standard for the solvent sensor to pass the test is that the concentration of solvent in the purge outlet airflow is below 1000 ppm.

7. The method for repairing defects on the inner side of a hollow fiber membrane according to claim 1, characterized in that: The heat treatment temperature is 30 ℃ ~ 80 ℃, and the heat treatment duration is 1 h ~ 24 h.

8. A hollow fiber membrane inner defect repair device for use in any one of the defect repair methods of claims 1 to 7, characterized in that: Includes a filling liquid storage tank (1), a centrifugal pump (2), a filter (3), a vacuum pump, a purging mechanism, and at least one workpiece support; a hollow fiber membrane assembly (4) is placed on the workpiece support; The outlet of the filling liquid storage tank (1) is connected to the inlet of the inner channel of the hollow fiber membrane module (4) through a pipeline, and a centrifugal pump (2) and a filter (3) are sequentially installed on the pipeline in the direction of liquid flow; the inlet of the filling liquid storage tank (1) is connected to the outlet of the inner channel of the hollow fiber membrane module (4) through a pipeline. The vacuum pump is connected to the outer channel inlet and / or outer channel outlet of the hollow fiber membrane module (4); The purging mechanism includes a gas cylinder (5) and a solvent sensor; the gas cylinder (5) is connected to the inlet of the inner channel of the hollow fiber membrane module (4) through a pipeline; the solvent sensor is installed on the pipeline at the outlet of the inner channel of the hollow fiber membrane module (4).

9. The hollow fiber membrane inner defect repair device according to claim 8, characterized in that: When multiple hollow fiber membrane modules (4) are repaired at the same time, the multiple hollow fiber membrane modules (4) are connected in series or in parallel; the inlet and outlet of the filling liquid storage tank (1) and the multiple hollow fiber membrane modules (4) form a loop.

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