Mixers, polyacrylonitrile spinning solution on-line ammoniation devices and ammoniation methods

Abstract

The application provides a mixer, an online ammoniation device for polyacrylonitrile spinning solution and an ammoniation method, and belongs to the field of polyacrylonitrile spinning solution preparation. The ammoniation device comprises a defoaming device, a defoaming gear pump, a gas-liquid mixer, a micro-flow mixer, a storage mixing kettle, a spinning gear pump and a filter which are sequentially connected. The gas-liquid mixer, the micro-flow mixer and the storage mixing kettle are arranged, the contact area of ammonia gas and high-viscosity polymer solution is increased, the ammonia gas and the high-viscosity stock solution are fully mixed, the ammoniation degree is effectively controlled, and therefore the hydrophilic stability of the PAN spinning solution is improved. The ammoniation degree of the spinning solution is stable, the device has the characteristics of compact structure and high stability, the equipment investment and the production cost are greatly reduced, and the device has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of polyacrylonitrile spinning solution preparation, specifically involving a mixer, an online amination device for polyacrylonitrile spinning solution, and an amination method. Background Technology

[0002] Carbon fiber possesses advantages such as high strength, high modulus, high temperature resistance, and ablation resistance, and is widely used in aerospace, transportation, and sports and leisure fields. Among them, polyacrylonitrile (PAN)-based carbon fiber has become the fastest-growing, most diverse, and most widely used carbon fiber. The high performance of carbon fiber originates from PAN precursor fibers. The coagulation process is a key step in precursor fiber formation, significantly impacting the structure and properties of the precursor fibers. The coagulation double diffusion rate is related to the hydrophilicity of the PAN spinning solution. Improving the hydrophilicity of the PAN spinning solution helps control the coagulation process of nascent fibers, slows down the coagulation double diffusion rate, and inhibits the formation of macropores and core-sheath structures, thereby facilitating the acquisition of high-performance PAN precursor fibers with uniform and dense structures.

[0003] Currently, ammonia bubbling is commonly used to ammonify PAN polymerization solutions. Chinese patent publication CN1401675A discloses a method for preparing polyacrylonitrile-based carbon fiber spinning solutions. Ammonia is introduced into the polyacrylonitrile stock solution, causing ammonia to react with some of the carboxyl groups of itaconic acid to form ammonium salts. The pH of the stock solution is adjusted to between 8 and 10. This method is also the most commonly used to modify the hydrophilicity of the stock solution. Chinese patent publication CN105088422A discloses an ammonia-charging method in the preparation of polyacrylonitrile spinning solutions. An ammonia inlet is installed after the spinning solution flow meter, and an additional ammonia flow meter is added to control the amount of ammonia charged. A static mixer is installed after the ammonia inlet to ensure that the ammonia is fully mixed with the material before entering the degassing tank, which improves the uniform mixing of ammonia and spinning solution to a certain extent. The reaction between ammonia and PAN stock solution is a complex multiphase reaction. Due to the high viscosity of the PAN stock solution, mass transfer is difficult and hard to control, making it difficult to obtain a spinning solution with uniform ammoniation. The introduced ammonia is only absorbed by the solution at the points of contact, making it difficult to stably control the degree of ammoniation in the system. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art and provide an online ammoniation device and method for polyacrylonitrile spinning solution, which can achieve full mixing of ammonia gas and high viscosity raw solution, effectively control the degree of ammoniation, and thus improve the hydrophilic stability and spinnability of PAN spinning solution.

[0005] This invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention provides a gas-liquid mixer, comprising a liquid inlet, a vortex assembly, and a gas-liquid mixture outlet connected in sequence.

[0007] The vortex assembly includes a gas-liquid mixer central shaft. A clockwise vortex assembly and a counterclockwise vortex assembly are provided on the outer wall of the gas-liquid mixer central shaft. A gas chamber is sleeved on the outer side of the clockwise vortex assembly and the counterclockwise vortex assembly. A first ammonia inlet and a second ammonia inlet are opened on the outer wall of the gas chamber.

[0008] A further improvement of the present invention is that:

[0009] The clockwise vortex assembly consists of 2 to 30 vortex blades, which are arranged clockwise on the outer wall of the central shaft of the gas-liquid mixer. The clockwise twist angle is 10 to 90°. The width of the vortex blades gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades that are away from the central shaft of the gas-liquid mixer; and / or,

[0010] The ratio of the length of the vortex blade to the diameter of the clockwise vortex assembly is 0.5 to 2.0.

[0011] A further improvement of the present invention is that:

[0012] The counterclockwise vortex assembly consists of 2 to 30 vortex blades, which are arranged counterclockwise on the outer wall of the central shaft of the gas-liquid mixer, with a counterclockwise twist angle of 10 to 90°. The width of the vortex blades gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades that are away from the central shaft of the gas-liquid mixer; and / or,

[0013] The ratio of the length of the vortex blade to the diameter of the counterclockwise vortex assembly is 0.5 to 2.0.

[0014] A further improvement of the present invention is that:

[0015] The end of the clockwise vortex assembly with the larger vortex blade width is connected to the end of the counterclockwise vortex assembly with the smaller vortex blade width.

[0016] A further improvement of the present invention is that:

[0017] Both the clockwise and counterclockwise scroll components have ammonia scroll blade inlets and outlets on their scroll blades, preferably:

[0018] The vortex blade has a hollow structure, and one to ten 1-5 mm vent holes are provided on the end face of the vortex blade away from the central axis of the gas-liquid mixer. These vent holes are the ammonia vortex blade inlets; and / or,

[0019] The inner side of the torsion surface of the vortex blade is provided with small holes with a diameter of 0.1 to 1.0 mm. These small holes are the outlet of the ammonia vortex blade, and there are 1 to 5 rows of small holes, with 5 to 20 holes in each row.

[0020] A second aspect of the present invention provides a microfluidic mixer, comprising a microfluidic mixer housing, wherein one end of the microfluidic mixer housing is provided with a material inlet and the other end with a material outlet, and wherein an axial microfluidic mixing unit and a radial microfluidic mixing unit are provided inside the microfluidic mixer housing between the material inlet and the material outlet.

[0021] A further improvement of the present invention is that:

[0022] The axial microfluidic mixing unit includes a microfluidic mixer central shaft, and multiple axial swirl vanes are arranged circumferentially on the outer wall of the microfluidic mixer central shaft; preferably,

[0023] Multiple axial swirl vanes can be arranged circumferentially along the tangential direction, circumferentially along the central direction, uniformly in any direction, or randomly in any direction.

[0024] A further improvement of the present invention is that:

[0025] An axial swirl vane is composed of 3 to 50 swirl unit vanes connected along an axis. The twist angle of a single swirl unit vane is 180° to 360°, and the ratio of the twisted length of a single swirl unit vane to the maximum diameter of the axial swirl vane is 1 to 5; and / or,

[0026] The maximum diameter of an axial swirl vane is 0.05 to 0.2 times the inner diameter of the microfluidic mixer housing.

[0027] A further improvement of the present invention is that:

[0028] The radial microfluidic mixing unit is composed of 5 to 20 layers of radial swirl vanes arranged in an alternating pattern. The initial arrangement positions can be uniformly arranged in any direction or randomly arranged in any direction.

[0029] A further improvement of the present invention is that:

[0030] A single layer of radial swirl vanes is composed of 2 to 10 swirl unit vanes arranged radially and connected sequentially. The twist angle of a single swirl unit vane is 180° to 360°, and the ratio of the twisted length of a single swirl unit vane to the maximum diameter of the single layer of radial swirl vanes is 1 to 5; and / or,

[0031] The ratio of the diameter of one radial swirl vane to the inner diameter of the microfluidic mixer shell is 0.05 to 0.2.

[0032] A third aspect of the present invention provides an online ammoniation device for polyacrylonitrile spinning solution, comprising a degassing device, a degassing gear pump, a gas-liquid mixer, a microfluidic mixer, a storage mixing tank, a spinning gear pump, and a filter connected in sequence.

[0033] Multiple gas-liquid mixers are connected in series, preferably 1 to 10; and / or,

[0034] Multiple microfluidic mixers are connected in series, preferably 2 to 10.

[0035] A further improvement of the present invention is that:

[0036] The storage mixing vessel includes a storage mixing vessel body, and a stirring rod is arranged along the axial direction inside the storage mixing vessel body. Preferably, the stirring rod is provided with an upper layer blade, a middle layer blade, a lower layer blade and a lower center blade in sequence from top to bottom.

[0037] A further improvement of the present invention is that:

[0038] The diameters of the upper and middle blades are 0.7 to 0.95 times the inner diameter of the mixing vessel body; and / or,

[0039] The upper blades and the middle blades are arranged alternately, and the axes of the upper blades and the middle blades are perpendicular to each other in the same plane.

[0040] A further improvement of the present invention is that:

[0041] The diameter of the lower impeller is 0.9 to 0.98 times the inner diameter of the storage mixing vessel; and / or,

[0042] The diameter of the lower central impeller is 0.4 to 0.6 times the inner diameter of the storage mixing vessel body; and / or,

[0043] The lower blades and the lower center blades are arranged alternately, and the axes of the lower blades and the lower center blades are perpendicular to each other in the same plane.

[0044] A further improvement of the present invention is that:

[0045] A broken threaded strip is provided between the middle blade and the lower blade; and / or,

[0046] An arc-shaped blade is provided between the lower blade and the lower center blade.

[0047] A further improvement of the present invention is that:

[0048] The top of the storage mixing vessel body is provided with a raw liquid inlet, and a raw liquid inlet pipe is inserted into the raw liquid inlet. The raw liquid inlet pipe is located at one end of the storage mixing vessel body near the stirring shaft, preferably 10-50mm away from the stirring shaft.

[0049] A further improvement of the present invention is that:

[0050] The upper part of the stirring rod is provided with a liquid limiting ring, which is located below the end of the raw liquid feed pipe; the upper opening of the liquid limiting ring is larger, and its diameter is 1 / 10 to 1 / 5 of the inner diameter of the storage mixing vessel body, while the lower opening is smaller, and its diameter is 1 / 8 to 1 / 2 of the diameter of the upper opening.

[0051] The length of the liquid-limiting ring is 0.5 to 2.0 times the diameter of the upper opening, and the annular gap width between the lower opening of the liquid-limiting ring and the stirring shaft is 1 to 10 mm.

[0052] A fourth aspect of the present invention provides an online ammoniation method for polyacrylonitrile spinning solution, wherein the polyacrylonitrile spinning solution is ammoniated using the aforementioned online ammoniation device for polyacrylonitrile spinning solution.

[0053] The method is specifically as follows:

[0054] The polyacrylonitrile spinning solution in the degassing device enters the gas-liquid mixer through the degassing gear pump. The spinning solution is divided into multiple swirling streams by the vortex blades. At the same time, ammonia gas enters the gas chamber through the first ammonia inlet and the second ammonia inlet. The ammonia gas entering the gas chamber enters the hollow structure of the vortex blade through the ammonia vortex blade inlet, and then flows out from the ammonia vortex blade outlet. The outflowing ammonia gas mixes with the spinning solution through counterclockwise and / or clockwise vortexes and then enters the microfluidic mixer. The gas-liquid mixture is divided into multiple microfluids in the axial microfluidic mixing unit and the radial microfluidic mixing unit. The microfluids flow radially, tangentially and axially. After passing through multiple sets of microfluidic mixers, the mixture is continuously divided into multiple microfluids and then mixed and divided to achieve full mixing. The mixture then flows into the storage mixing tank. Under the stirring action of the storage mixing tank, the homogeneity is improved and air bubbles are not entrained. After passing through the spinning gear pump and filter, it is used for stable spinning.

[0055] A further improvement of the present invention is that:

[0056] The ratio of the ammonia molar flow rate at the first ammonia inlet to the ammonia molar flow rate at the second ammonia inlet is 1 to 9:1; and / or,

[0057] The ammonia gas temperature range is 20–40°C; and / or,

[0058] The gas velocity of ammonia at the outlet of the ammonia vortex blade ranges from 0.001 to 0.01 m / s.

[0059] A further improvement of the present invention is that:

[0060] The polyacrylonitrile spinning solution has a temperature range of 40–70°C; and / or,

[0061] The flow velocity of the spinning solution in the empty tubes of the gas-liquid mixer and microfluidic mixer ranges from 0.01 to 0.1 m / s.

[0062] A further improvement of the present invention is that:

[0063] The ratio of the molar amount of ammonia to the molar amount of carboxyl groups in itaconic acid in the polyacrylonitrile spinning solution ranges from 0.1 to 1.0; and / or,

[0064] The pH value of the spinning solution after ammonia treatment is controlled within the range of 8.0 to 10.

[0065] A further improvement of the present invention is that:

[0066] The stirring speed range of the storage mixing vessel is 1–60 rpm; and / or,

[0067] The liquid level is lower than the raw material inlet, and is 0.1 to 0.8 times the height of the storage mixing vessel.

[0068] Compared with the prior art, the beneficial effects of the present invention are:

[0069] 1) The spinning solution is divided into multiple flow zones by the gas-liquid mixer. Under vortex flow, it mixes with ammonia gas from the outlet of multiple ammonia vortex blades, which increases the gas-liquid contact area, promotes the mixing of liquid between vortex blades, and improves the gas-liquid mixing and dissolution efficiency.

[0070] 2) Ammonia gas flows through the gas chamber from the ammonia vortex blade inlet to the ammonia vortex blade outlet on the blade surface, ensuring a uniform flow of ammonia into the vortex blade. The ammonia gas exits from the back pressure surface of the vortex blade, where the lower pressure allows for backflow, ensuring sufficient contact between the entrained ammonia gas and the spinning solution. Ammonia gas enters from both the first and second ammonia inlets, preventing the formation of large bubbles. This stepwise ammoniation process achieves uniform ammoniation degree and improves the ammoniation reaction efficiency.

[0071] 3) The microfluidic mixer, through the staggered arrangement of axial and radial microfluidic mixers, can promote the radial, circumferential and axial flow of the ammoniated spinning solution, and has strong swirling, eddy and shearing effects, which promotes the heat and mass transfer of the spinning solution. It has the characteristics of high mixing efficiency, uniform heating and low pressure drop.

[0072] 4) The feed spinning solution flows along the stirring rod in the storage mixing tank. Under the stirring of the radial upper and middle stirring blades, air bubbles will not be entrained. The mixed ammoniated spinning solution is stirred evenly. The combination of the broken spiral ribbon, arc-shaped blade, lower blade and lower center blade can make the spinning solution stirred evenly and there is no dead zone.

[0073] This invention increases the contact area between ammonia and the high-viscosity polymerization solution by incorporating a gas-liquid mixer, a microfluidic mixer, and a storage mixing tank. This achieves thorough mixing of ammonia and the high-viscosity raw material, effectively controlling the degree of ammoniation and thus improving the hydrophilic stability of the PAN spinning solution. It can stabilize the degree of ammoniation of the spinning solution and also features a compact structure and high stability, significantly reducing equipment investment and production costs, and has good application prospects. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of an online ammoniation device for polyacrylonitrile spinning solution provided by the present invention;

[0075] Figure 2 This is a schematic diagram of a gas-liquid mixer.

[0076] Figure 3 This is a magnified view of a gas-liquid mixer.

[0077] Figure 4 This is a schematic diagram of the structure of an axial microfluidic mixing unit;

[0078] Figure 5 This is a cross-sectional view of an axial microfluidic mixing unit;

[0079] Figure 6 This is a structural attempt at a radial microfluidic mixing unit;

[0080] Figure 7 This is a cross-sectional view of a radial microfluidic mixing unit;

[0081] Figure 8 This is a schematic diagram of the structure of the material storage and mixing vessel.

[0082] In the diagram, 1. Degassing device, 2. Degassing gear pump, 3. Ammonia gas source, 4. Gas flow meter, 5. Gas-liquid mixer, 51. Liquid inlet, 52. First ammonia inlet, 53. Second ammonia inlet, 54. Gas chamber, 55. Ammonia vortex blade inlet, 56. Ammonia vortex blade outlet, 57. Vortex blade, 58. Central shaft of gas-liquid mixer, 59. Gas-liquid mixture outlet, 6. Microfluidic mixer, 61. Material inlet, 62. Axial swirl vane, 63. Central shaft of microfluidic mixer, 64. Radial swirl vane, 65. Material outlet, 7. Storage mixing vessel, 71. Raw liquid inlet, 72. Upper blade, 73. Middle blade, 74. Broken screw ribbon, 75. Lower large blade, 76. Lower center blade, 77. Arc blade, 78. Liquid limiting ring, 8. Spinning gear pump, 9. Filter. Detailed Implementation

[0083] The present invention will now be described in further detail with reference to the accompanying drawings:

[0084] like Figures 1-8As shown, the present invention provides an online ammoniation device for polyacrylonitrile spinning solution, comprising a degassing device 1, a degassing gear pump 2, a gas-liquid mixer 5, a microfluidic mixer 6, a storage mixing tank 7, a spinning gear pump 8, and a filter 9 connected in sequence.

[0085] The gas-liquid mixer 5 is connected to an ammonia cylinder 3 via a pipeline, and a gas flow meter 4 is installed on the pipeline.

[0086] The bottom outlet of the degassing device 1 is connected to the inlet of the degassing gear pump 2. The outlet of the degassing gear pump 2 is connected to the liquid phase inlet 51 of the gas-liquid mixer 5. The ammonia cylinder 3 is connected to the first ammonia inlet 52 and the second ammonia inlet 53 of the gas-liquid mixer 5 through the first pipe and the second pipe, respectively. Gas flow meters 4 are installed on the first pipe and the second pipe, respectively. The gas-liquid mixture outlet 59 of the gas-liquid mixer 5 is connected to the material inlet 61 of the microfluidic mixer 6. The material outlet 65 of the microfluidic mixer 6 is connected to the raw liquid inlet 71 of the storage mixing vessel 7. The bottom outlet of the storage mixing vessel 7 is connected to the spinning gear pump 8. The spinning gear pump 8 is connected to the filter 9.

[0087] The polyacrylonitrile polymerization solution in the degassing device 1 enters the gas-liquid mixer 5 through the degassing gear pump 2. The solution is divided into multiple swirling streams in the gas-liquid mixer 5. Ammonia gas is metered from the ammonia gas cylinder 3 through the gas flow meter 4 and then introduced into the gas-liquid mixer 5. After being mixed with the spinning solution by multiple sets of vortex components in a counterclockwise and / or clockwise vortex, it enters the microfluidic mixer 6. Through the process of continuously dividing into multiple microfluids and then mixing and dividing, full mixing is achieved. After that, it flows into the storage mixing tank 7. Under the stirring action of the storage mixing tank 7, the homogeneity is improved and no air bubbles are entrained. Then, it passes through the spinning gear pump 8 and the filter 9 in sequence for stable spinning. This achieves full mixing of ammonia gas and high viscosity dope, effectively controls the degree of ammoniaization, and thus improves the hydrophilic stability and spinnability of the PAN spinning solution.

[0088] Among them, the defoaming device 1, the defoaming gear pump 2, the spinning gear pump 8 and the filter 9 all use existing conventional equipment, which will not be described in detail here.

[0089] As a preferred embodiment of the present invention, the online ammonia treatment device for polyacrylonitrile spinning solution provided by the present invention can be equipped with multiple gas-liquid mixers 5 in series, preferably 1 to 10, and adjacent gas-liquid mixers 5 can be connected by any means such as flanges, threads or clamps, without specific limitations.

[0090] like Figure 2 and Figure 3As shown, the gas-liquid mixer 5 includes a liquid inlet 51, a vortex assembly, and a gas-liquid mixture outlet 59 connected in sequence. The vortex assembly includes a central shaft 58 of the gas-liquid mixer. A clockwise vortex assembly and a counterclockwise vortex assembly are provided on the outer wall of the central shaft 58, and both the clockwise and counterclockwise vortex assemblies are welded to the central shaft 58 for limiting and fixing. A gas chamber 54 is sleeved on the outer side of the clockwise and counterclockwise vortex assemblies. A first ammonia inlet 52 and a second ammonia inlet 53 are provided on the outer wall of the gas chamber 54. The first ammonia inlet 52 and the second ammonia inlet 53 are located in the middle region of the gas chamber 54, preferably at 1 / 3 to 2 / 3 of the length of the gas chamber 54. The first ammonia inlet 52 and the second ammonia inlet 53 are respectively connected to an ammonia cylinder 3 through pipes, and the ammonia in the ammonia cylinder 3 enters the gas chamber 54 through the first ammonia inlet 52 and the second ammonia inlet 53.

[0091] Furthermore, the clockwise vortex assembly consists of 2 to 30 vortex blades 57, which are arranged clockwise on the outer wall of the central shaft 58 of the gas-liquid mixer. The clockwise twist angle is 10 to 90°. The width of the vortex blades 57 gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the clockwise vortex assembly is 0.5 to 2.0.

[0092] Furthermore, the counterclockwise vortex assembly consists of 2 to 30 vortex blades 57, which are arranged counterclockwise on the outer wall of the central shaft 58 of the gas-liquid mixer, with a counterclockwise twist angle of 10 to 90°. The width of the vortex blades 57 gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the counterclockwise vortex assembly is 0.5 to 2.0.

[0093] The wider end of the vortex blade 57 in the clockwise vortex assembly is connected to the narrower end of the vortex blade 57 in the counterclockwise vortex assembly.

[0094] Furthermore, both the clockwise and counterclockwise vortex components have ammonia vortex blade inlet 55 and ammonia vortex blade outlet 56 on the vortex blade 57. Specifically, the vortex blade 57 is a hollow structure, and 1 to 10 1 to 5 mm vent holes are provided on the end face of the vortex blade 57 away from the central axis 58 of the gas-liquid mixer. These vent holes are the ammonia vortex blade inlet 55. The inner side of the torsion surface of the vortex blade 57 (i.e., the torsion direction side) is provided with small holes with a diameter of 0.1 to 1.0 mm. These small holes are the ammonia vortex blade outlet 56, and there are 1 to 5 rows of these small holes, with 5 to 20 holes in each row. Ammonia gas entering the gas chamber 54 through the first ammonia inlet 52 and the second ammonia inlet 53 enters the hollow structure of the vortex blade 57 through the ammonia vortex blade inlet 55, and then flows out through the ammonia vortex blade outlet 56. The outflowing ammonia gas mixes with the spinning solution entering through the liquid inlet 51.

[0095] Since the pressure of ammonia gas at the outlet 56 of the ammonia vortex blade is greater than the pressure of the spinning solution at that point, and the pressure of the spinning solution is lower at that point due to the torsion of the vortex blade 57, the spinning solution will not enter the hollow structure of the vortex blade 57.

[0096] As a preferred embodiment of the present invention, the online ammonia treatment device for polyacrylonitrile spinning solution provided by the present invention can be equipped with multiple microfluidic mixers 6 in series, preferably 2 to 10, and adjacent microfluidic mixers 6 can be connected by any means such as flange, thread or clamp, without specific limitation.

[0097] The microfluidic mixer 6 includes a microfluidic mixer housing, with a material inlet 61 at one end and a material outlet 65 at the other end. An axial microfluidic mixing unit and a radial microfluidic mixing unit are provided inside the microfluidic mixer housing between the material inlet 61 and the material outlet 65.

[0098] like Figure 4 and Figure 5 As shown, the axial microfluidic mixing unit includes a microfluidic mixer central shaft 63. Multiple axial swirl vanes 62 are arranged circumferentially on the outer wall of the central shaft 63. These vanes can be arranged tangentially, circumferentially along the center direction, uniformly in any direction, or randomly in any direction. Preferably, there are 20 to 100 axial swirl vanes 62.

[0099] An axial swirl vane 62 is composed of 3 to 50 swirl unit vanes connected along the axis. The twist angle of a single swirl unit vane is 180° to 360°, and the ratio of the length of a single swirl unit vane after twisting to the maximum diameter of an axial swirl vane 62 is 1 to 5. The maximum diameter of an axial swirl vane 62 is 0.05 to 0.2 of the inner diameter of the microfluidic mixer shell.

[0100] like Figure 6 and Figure 7 As shown, the radial microfluidic mixing unit is composed of 5 to 20 layers of radial swirl vanes 64 arranged in an alternating pattern. The initial arrangement positions can be uniformly arranged in any direction or randomly arranged in any direction.

[0101] A radial swirl vane 64 is composed of 2 to 10 swirl unit vanes arranged and connected radially. The twist angle of a single swirl unit vane is 180° to 360°, and the ratio of the length of a single swirl unit vane after twisting to the maximum diameter of the radial swirl vane 64 is 1 to 5. The ratio of the diameter of the radial swirl vane to the inner diameter of the microfluidic mixer shell is 0.05 to 0.2.

[0102] It should be noted that the swirl unit plates that make up the axial swirl vane and the swirl unit plates that make up the radial swirl vane can have the same or different structures, as long as the structural requirements are met.

[0103] As a preferred embodiment of the present invention, such as Figure 8 As shown, the storage mixing vessel 7 includes a storage mixing vessel body. A stirring rod is arranged along the axial direction inside the storage mixing vessel body. The stirring rod is provided with an upper impeller 72, a middle impeller 73, a lower impeller 75, and a lower center impeller 76 arranged sequentially from top to bottom.

[0104] The upper impeller 72 and the middle impeller 73 are radial flow mixing impellers such as two-blade straight blades, three-blade swept blades, and Burmäkin type. The diameter of the upper impeller 72 and the middle impeller 73 is 0.7 to 0.95 of the inner diameter of the storage mixing vessel. The upper impeller 72 and the middle impeller 73 are arranged alternately, that is, the axes of the upper impeller 72 and the middle impeller 73 are perpendicular to each other in the same plane.

[0105] A broken spiral band 74 is provided between the middle layer blade 73 and the lower layer blade 75. When the broken spiral band 74 rotates, it can stir the liquid near the wall between the middle layer blade 73 and the lower layer blade 75, so that the liquid spirals up along the tank wall and then flows down along the blade shaft, forming an axial circulation flow inside the liquid, which has a good vertical circulation capability.

[0106] The lower impeller 75 and the lower center impeller 76 are anchor-type, frame-type, or bottom-arc-type impellers. The diameter of the lower impeller 75 is 0.9 to 0.98 times the inner diameter of the storage mixing vessel body, and the diameter of the lower center impeller 76 is 0.4 to 0.6 times the inner diameter of the storage mixing vessel body. The lower impeller 75 and the lower center impeller 76 are arranged alternately, meaning that the axes of the lower impeller 75 and the lower center impeller 76 are perpendicular to each other in the same plane. An arc-shaped impeller 77 is provided between the lower impeller 75 and the lower center impeller 76. The function of the arc-shaped impeller 77 is to stir the liquid between the lower impeller 75 and the lower center impeller 76, resulting in a certain radial and axial mixing flow, and also to fix the lower impeller 75 and the lower center impeller 76.

[0107] The top of the storage mixing vessel is provided with a raw liquid inlet, and a raw liquid feed pipe is inserted into the raw liquid inlet. The raw liquid feed pipe is located at one end of the storage mixing vessel body, close to the stirring shaft, and 10-50mm away from the stirring shaft.

[0108] A liquid-limiting ring 78 is provided at the upper part of the stirring rod, located below the end of the raw liquid inlet pipe. The upper opening of the liquid-limiting ring 78 is relatively large, with a diameter of 1 / 10 to 1 / 5 of the inner diameter of the storage mixing vessel body, while the lower opening is relatively small, with a diameter of 1 / 8 to 1 / 2 of the upper opening diameter. The length of the liquid-limiting ring 78 is 0.5 to 2.0 mm of the upper opening diameter, resembling a funnel shape. The annular gap width between the lower opening and the stirring shaft is 1 to 10 mm.

[0109] The spinning solution entering through the feed pipe enters the liquid-limiting ring 78. Part of the spinning solution flows into the liquid phase body along the stirring shaft through the annular gap between the lower opening and the stirring shaft. Another part of the spinning solution accumulates at the upper opening of the liquid-limiting ring and overflows from the outer edge of the upper opening, flowing downward along the outer wall and the stirring shaft. Subsequently, the spinning solution enters the liquid phase body along the stirring shaft.

[0110] By setting a liquid limiting ring 78, the spinning solution is received through the liquid limiting ring 78 and allowed to flow downward along the stirring axis into the liquid phase body, thus preventing the spinning solution from falling directly into the liquid phase body and thus entraining a large number of air bubbles, which would affect subsequent spinning.

[0111] This invention also provides an online amination method for polyacrylonitrile spinning solution, wherein the above-mentioned online amination device for polyacrylonitrile spinning solution is used to amination the polyacrylonitrile spinning solution, specifically as follows:

[0112] The polyacrylonitrile spinning solution in the degassing device 1 enters the gas-liquid mixer 5 through the degassing gear pump 2. The spinning solution is divided into multiple swirling streams by the vortex blades 57. Simultaneously, ammonia gas from the ammonia cylinder 3, after being metered by the gas flow meter 4, enters the gas chamber 54 through the first ammonia inlet 52 and the second ammonia inlet 53. The ammonia gas entering the gas chamber 54 enters the hollow structure of the vortex blades 57 through the ammonia vortex blade inlet 55, and then flows out from the ammonia vortex blade outlet 56. The outflowing ammonia gas and the spinning solution flow counterclockwise and... / Or after clockwise vortex mixing, it enters the microfluidic mixer 6. The gas-liquid mixture is divided into multiple microfluids in the axial microfluidic mixing unit and the radial microfluidic mixing unit. It flows along the radial, tangential and axial directions. After passing through multiple sets of microfluidic mixers 6, it is fully mixed by continuously dividing it into multiple microfluids and then mixing and dividing it. Then it flows into the storage mixing tank 7. Under the stirring action of the storage mixing tank 7, the homogeneity is improved and no air bubbles are entrained. After passing through the spinning gear pump 8 and the filter 9, it is used for stable spinning.

[0113] The temperature range of the polyacrylonitrile spinning solution is 40–70°C, and the flow velocity of the spinning solution in the empty tubes of the gas-liquid mixer 5 and the microfluidic mixer 6 ranges from 0.01 to 0.1 m / s.

[0114] The ammonia temperature ranges from 20 to 40°C, and the ammonia gas velocity at the ammonia vortex blade outlet 56 ranges from 0.001 to 0.01 m / s.

[0115] The ratio of the number of moles of ammonia to the number of moles of carboxyl groups in itaconic acid in the polyacrylonitrile spinning solution ranges from 0.1 to 1.0.

[0116] The ratio of the ammonia molar flow rate of the first ammonia inlet 52 to the ammonia molar flow rate of the second ammonia inlet 53 is 1 to 9:1.

[0117] The pH value of the spinning solution after ammonia treatment is controlled within the range of 8.0 to 10.

[0118] The stirring speed of the storage mixing vessel 7 is in the range of 1 to 60 rpm, and the liquid level is lower than the raw liquid inlet 71, which is 0.1 to 0.8 times the height of the storage mixing vessel 7.

[0119]

Example 1

[0120] The structure of the ammoniation device used in this embodiment is as follows: it includes a degassing device 1, a degassing gear pump 2, a gas-liquid mixer 5, a microfluidic mixer 6, a storage mixing tank 7, a spinning gear pump 8, and a filter 9 connected in sequence. The first ammonia inlet 52 and the second ammonia inlet 53 of the gas-liquid mixer 5 are respectively connected to an ammonia cylinder 3 through pipelines, and a gas flow meter 4 is installed on each pipeline.

[0121] The gas-liquid mixer 5 is provided with one unit. The clockwise vortex assembly in the gas-liquid mixer 5 consists of 10 vortex blades 57, which are arranged clockwise on the outer wall of the central shaft 58 of the gas-liquid mixer. The clockwise twist angle is 30°. The width of the vortex blades 57 gradually increases from one end to the other. A shell is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the clockwise vortex assembly is 2.

[0122] The counterclockwise vortex assembly consists of 10 vortex blades 57, which are arranged counterclockwise on the outer wall of the central shaft 58 of the gas-liquid mixer, with a counterclockwise twist angle of 30°. The width of the vortex blades 57 gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the counterclockwise vortex assembly is 2.

[0123] The vortex blade 57 has a hollow structure. On the end face of the vortex blade 57 away from the central axis 58 of the gas-liquid mixer, there are 6 2mm air holes. These air holes are the ammonia vortex blade inlet 55. On the inner side of the twisting surface of the vortex blade 57 (i.e. the twisting direction side), there are small holes with a diameter of 0.5mm. These small holes are the ammonia vortex blade outlet 56. There are 2 rows of these small holes, with 10 holes in each row.

[0124] The microfluidic mixer is configured in series with two units. The axial microfluidic mixing unit consists of 30 axial swirl vanes 62 arranged circumferentially on the outer wall of the central shaft 63 of the microfluidic mixer. Each axial swirl vane 62 consists of 10 swirl vane units connected along the axis. The twist angle of a single swirl vane is 360°, and the ratio of the twisted length of a single swirl vane to the maximum diameter of the swirl vane is 2. The maximum diameter of a single axial swirl vane 62 is 0.1 times the inner diameter of the microfluidic mixer shell.

[0125] The radial microfluidic mixing unit consists of 10 layers of radial swirl vanes 64 arranged in an alternating pattern. Each layer of radial swirl vanes 64 is composed of 6 swirl unit vanes arranged and connected radially. The twist angle of a single swirl unit vane is 360°, and the ratio of the length of a single swirl unit vane after twisting to the maximum diameter of the swirl vane is 2. The ratio of the diameter of a layer of radial swirl vanes to the inner diameter of the microfluidic mixer shell is 0.1.

[0126] In the storage mixing tank 7, the raw liquid feed pipe is located at one end of the storage mixing tank body near the stirring shaft, and a limited liquid ring is provided. The upper and middle layer blades are two-blade straight blade stirring blades with a blade diameter of 0.8 times the inner diameter of the storage mixing tank body. The lower layer blades and the lower center blades are anchor frame type, with the lower layer blade diameter being 0.95 times the inner diameter of the storage mixing tank body and the lower center blade diameter being 0.5 times the inner diameter of the storage mixing tank body. A broken screw ribbon is provided between the upper and middle layer blades, and an arc-shaped blade is provided between the lower layer blades and the lower center blade.

[0127] The polyacrylonitrile spinning solution is aminated using the online ammoniation device of Example 1, specifically as follows:

[0128] A 45°C polyacrylonitrile solution enters the gas-liquid mixer 5 from the degassing device 1 via the degassing gear pump 2. The spinning solution is divided into multiple swirling streams by the vortex blades 57. Simultaneously, ammonia gas enters the gas chamber 54 from the ammonia cylinder 3 via the gas flow meter 4, passing through the first ammonia inlet 52 and the second ammonia inlet 53. The ratio of the molar number of ammonia gas to the molar number of carboxyl groups in itaconic acid in the polyacrylonitrile spinning solution is 0.2. The ratio of the ammonia molar flow rate at the first ammonia inlet 52 to the ammonia molar flow rate at the second ammonia inlet 53 is 0.8:0.2. The ammonia gas entering the gas chamber 54 enters the hollow structure of the vortex blade 57 through the ammonia vortex blade inlet 55 and then flows out from the ammonia vortex blade outlet 56. The gas velocity of the ammonia gas flowing out from the ammonia vortex blade outlet 56 is 0.005 m / s. The outflowing ammonia gas and the spinning solution flow counterclockwise and / or clockwise. After vortex mixing, the solution enters the microfluidic mixer 6. The flow velocity of the spinning solution in the empty tubes of the gas-liquid mixer 5 and the microfluidic mixer 6 is 0.05 m / s. The gas-liquid mixture is divided into multiple microflows in the axial and radial microfluidic mixing units, flowing radially, tangentially, and axially. After passing through multiple sets of microfluidic mixers 6, the solution is continuously divided into multiple microflows and then mixed again to achieve thorough mixing before flowing into the storage mixing tank 7. The stirring speed of the storage mixing tank is 15 rpm, and the liquid level is 0.5 times the height of the storage mixing tank 7. Under the stirring action of the storage mixing tank 7, the homogeneity is improved and air bubbles are not entrained. After passing through the spinning gear pump 8 and the filter 9, the solution is used for stable spinning. The average pH value after ammonia treatment is 8.5, the pH CV value is 1.5%, and the actual degree of ammonia treatment obtained by acid-base titration is 0.2.

[0129]

Examples 2-9

[0130] The ammoniation apparatus and method in Examples 2-9 are the same as in Example 1, except that the parameters that differ from those in Example 1 are shown in Table 1. The online ammoniation apparatus in Example 1 is used, and the variations are: the number of air holes in the gas chamber, the number of rows and the number of holes per row at the outlet of the ammonia vortex blades, the number of microfluidic mixer combinations, the distance between the raw liquid inlet and the wall, the type of the upper and middle layer blades, the type of the lower layer center blade, and the condition of broken spiral ribbons and arc-shaped blades. The parameters that differ from those in Example 1 in the method are shown in Table 2. The online ammoniation method in Example 1 is used, and the variation is the ratio of the ammonia molar flow rate at the first ammonia inlet to that at the second ammonia inlet.

[0131] Table 1 Parameters that differ from those in Example 1

[0132]

[0133] It should be noted that Example 9 is intended to illustrate the effect of different ratios of the first ammonia inlet to the second ammonia inlet. In Table 2, the ratio of the first ammonia inlet to the second ammonia inlet in Example 9 is 10:0, which means that ammonia is introduced from the first ammonia inlet.

[0134] Table 2 shows the parameters that differ between the method and Example 1.

[0135]

[0136]

[0137] Comparative Example 1

[0138] Ammoniated polyacrylonitrile spinning solution is prepared using an existing ammoniation device. The device consists of an ammonia inlet on the spinning solution pipeline, an ammonia flow meter, and a static mixer (commercially available, SK type mixing element, manufactured by Qidong Qiyuan Metallurgical Petrochemical Machinery Equipment Manufacturing Co., Ltd.) installed after the ammonia inlet. The ammonia is then mixed with the material before entering the degassing reactor.

[0139] The existing ammoniation apparatus and method use a polyacrylonitrile spinning solution at a temperature of 45°C and an ammonia temperature of 30°C. The ratio of the number of moles of ammonia to the number of moles of carboxyl groups in itaconic acid in the polyacrylonitrile spinning solution is 0.2. The ammoniation test results show that bubbles are found in the spinning solution in the degassing kettle, the pH value is 8.2, and the pH CV value is 3.0%. The degree of ammoniation of the spinning solution is 0.161 obtained by acid-base titration. See Table 3 for details.

[0140] Comparative Example 2

[0141] The structure of the ammoniation device used in this comparative example is as follows: it includes a degassing device 1, a degassing gear pump 2, a gas-liquid mixer 5, a spinning gear pump 8 and a filter 9 connected in sequence. The first ammonia inlet 52 and the second ammonia inlet 53 of the gas-liquid mixer 5 are respectively connected to an ammonia cylinder 3 through pipelines, and a gas flow meter 4 is installed on each pipeline.

[0142] The gas-liquid mixer 5 is provided with one unit. The clockwise vortex assembly in the gas-liquid mixer 5 consists of 10 vortex blades 57, which are arranged clockwise on the outer wall of the central shaft 58 of the gas-liquid mixer. The clockwise twist angle is 30°. The width of the vortex blades 57 gradually increases from one end to the other. A shell is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the clockwise vortex assembly is 2.

[0143] The counterclockwise vortex assembly consists of 10 vortex blades 57, which are arranged counterclockwise on the outer wall of the central shaft 58 of the gas-liquid mixer, with a counterclockwise twist angle of 30°. The width of the vortex blades 57 gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the counterclockwise vortex assembly is 2.

[0144] The vortex blade 57 has a hollow structure. On the end face of the vortex blade 57 away from the central axis 58 of the gas-liquid mixer, there are 6 2mm air holes. These air holes are the ammonia vortex blade inlet 55. On the inner side of the twisting surface of the vortex blade 57 (i.e. the twisting direction side), there are small holes with a diameter of 0.5mm. These small holes are the ammonia vortex blade outlet 56. There are 2 rows of these small holes, with 10 holes in each row.

[0145] The ammoniation apparatus used in this comparative example was used to ammoniate the polyacrylonitrile spinning solution, specifically as follows:

[0146] A 45°C polyacrylonitrile solution enters the gas-liquid mixer 5 from the degassing device 1 via the degassing gear pump 2. The spinning solution is divided into multiple swirling streams by the vortex blades 57. Simultaneously, ammonia gas enters the gas chamber 54 from the ammonia cylinder 3 via the gas flow meter 4, passing through the first ammonia inlet 52 and the second ammonia inlet 53. The ratio of the molar number of ammonia gas to the molar number of carboxyl groups in itaconic acid in the polyacrylonitrile spinning solution is 0.2, and the ratio of the ammonia molar flow rate at the first ammonia inlet 52 to the ammonia molar flow rate at the second ammonia inlet 53 is 0.8:0.2. Ammonia gas in section 4 enters the hollow structure of vortex blade 57 through ammonia vortex blade inlet 55, and then flows out from ammonia vortex blade outlet 56. The gas velocity of ammonia gas flowing out from ammonia vortex blade outlet 56 is 0.005 m / s. The outflowing ammonia gas and spinning solution are used for stable spinning after passing through spinning gear pump 8 and filter 9. The relevant ammoniaization test results show that bubbles are found in the spinning solution, the pH value is 8.3, the pH CV value is 2.5%, and the ammoniaization degree of the spinning solution is 0.177 obtained by acid-base titration. See Table 3 for details.

[0147] Comparative Example 3

[0148] The structure of the ammoniation device used in this comparative example is as follows: it includes a degassing device 1, a degassing gear pump 2, a gas-liquid mixer 5, a microfluidic mixer 6, a spinning gear pump 8 and a filter 9 connected in sequence. The first ammonia inlet 52 and the second ammonia inlet 53 of the gas-liquid mixer 5 are respectively connected to an ammonia cylinder 3 through pipelines, and a gas flow meter 4 is installed on each pipeline.

[0149] The gas-liquid mixer 5 is provided with one unit. The clockwise vortex assembly in the gas-liquid mixer 5 consists of 10 vortex blades 57, which are arranged clockwise on the outer wall of the central shaft 58 of the gas-liquid mixer. The clockwise twist angle is 30°. The width of the vortex blades 57 gradually increases from one end to the other. A shell is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the clockwise vortex assembly is 2.

[0150] The counterclockwise vortex assembly consists of 10 vortex blades 57, which are arranged counterclockwise on the outer wall of the central shaft 58 of the gas-liquid mixer, with a counterclockwise twist angle of 30°. The width of the vortex blades 57 gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades 57 that are away from the central shaft 58 of the gas-liquid mixer. The ratio of the length of the vortex blades to the diameter of the counterclockwise vortex assembly is 2.

[0151] The vortex blade 57 has a hollow structure. On the end face of the vortex blade 57 away from the central axis 58 of the gas-liquid mixer, there are 6 2mm air holes. These air holes are the ammonia vortex blade inlet 55. On the inner side of the twisting surface of the vortex blade 57 (i.e. the twisting direction side), there are small holes with a diameter of 0.5mm. These small holes are the ammonia vortex blade outlet 56. There are 2 rows of these small holes, with 10 holes in each row.

[0152] The microfluidic mixer is configured in series with two units. The axial microfluidic mixing unit consists of 30 axial swirl vanes 62 arranged circumferentially on the outer wall of the central shaft 63 of the microfluidic mixer. Each axial swirl vane 62 consists of 10 swirl vane units connected along the axis. The twist angle of a single swirl vane is 360°, and the ratio of the twisted length of a single swirl vane to the maximum diameter of the swirl vane is 2. The maximum diameter of a single axial swirl vane 62 is 0.1 times the inner diameter of the microfluidic mixer shell.

[0153] The radial microfluidic mixing unit consists of 10 layers of radial swirl vanes 64 arranged in an alternating pattern. Each layer of radial swirl vanes 64 is composed of 6 swirl unit vanes arranged and connected radially. The twist angle of a single swirl unit vane is 360°, and the ratio of the length of a single swirl unit vane after twisting to the maximum diameter of the swirl vane is 2. The ratio of the diameter of a layer of radial swirl vanes to the inner diameter of the microfluidic mixer shell is 0.1.

[0154] The amination device of Comparative Example 3 was used to amination the polyacrylonitrile spinning solution, specifically as follows:

[0155] A 45°C polyacrylonitrile solution enters the gas-liquid mixer 5 from the degassing device 1 via the degassing gear pump 2. The spinning solution is divided into multiple swirling streams by the vortex blades 57. Simultaneously, ammonia gas enters the gas chamber 54 from the ammonia cylinder 3 after being metered by the gas flow meter 4 and passing through the first ammonia inlet 52 and the second ammonia inlet 53. The ratio of the molar number of ammonia gas to the molar number of carboxyl groups in itaconic acid in the polyacrylonitrile spinning solution is 0.2. The ratio of the ammonia molar flow rate at the first ammonia inlet 52 to the ammonia molar flow rate at the second ammonia inlet 53 is 0.8:0.2. The ammonia gas entering the gas chamber 54 enters the hollow structure of the vortex blade 57 through the ammonia vortex blade inlet 55 and then flows out from the ammonia vortex blade outlet 56. The gas velocity of the ammonia gas flowing out of the ammonia vortex blade outlet 56 is 0.00. The ammonia gas flowing out at a speed of 5 m / s mixes with the spinning solution in a counterclockwise and / or clockwise vortex before entering the microfluidic mixer 6. The flow velocity of the spinning solution in the empty tubes of the gas-liquid mixer 5 and the microfluidic mixer 6 is 0.05 m / s. The gas-liquid mixture is divided into multiple microfluids in the axial and radial microfluidic mixing units, flowing radially, tangentially, and axially. After passing through multiple sets of microfluidic mixers 6, the mixture is continuously divided into multiple microfluids and then mixed again to achieve thorough mixing. After passing through the spinning gear pump 8 and the filter 9, it is used for stable spinning. The relevant ammoniaization test results show that bubbles are found in the spinning solution, the pH value is 8.4, the pH CV value is 2.0%, and the ammoniaization degree of the spinning solution is 0.185 obtained by acid-base titration. See Table 3 for details.

[0156] Table 3

[0157]

[0158]

[0159] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0160] In the description of this invention, unless otherwise stated, the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention.

[0161] The above technical solution is only one embodiment of the present invention. For those skilled in the art, based on the principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the technical solutions described in the specific embodiments of the present invention. Therefore, the foregoing description is only a preferred option and is not restrictive.

Claims

1. A gas-liquid mixer, characterized in that, It includes a liquid inlet, a vortex assembly, and a gas-liquid mixture outlet that are connected in sequence; The vortex assembly includes a gas-liquid mixer central shaft. A clockwise vortex assembly and a counterclockwise vortex assembly are provided on the outer wall of the gas-liquid mixer central shaft. Both the clockwise and counterclockwise vortex assemblies are composed of 2 to 30 vortex blades. The vortex blades are hollow structures. An ammonia vortex blade inlet is provided on the end face of the vortex blade away from the gas-liquid mixer central shaft. An ammonia vortex blade outlet is provided on the inner side of the torsion surface of the vortex blade. The clockwise vortex assembly and the counterclockwise vortex assembly are fitted with air chambers on their outer sides. The outer wall of the air chambers is provided with a first ammonia inlet and a second ammonia inlet. The ammonia gas that enters the air chamber through the first ammonia inlet and the second ammonia inlet enters the hollow structure of the vortex blade through the ammonia vortex blade inlet, and then flows out through the ammonia vortex blade outlet. The outflowing ammonia gas mixes with the spinning solution that enters through the liquid inlet.

2. The gas-liquid mixer according to claim 1, characterized in that, In the clockwise vortex assembly, 2 to 30 vortex blades are arranged clockwise on the outer wall of the central shaft of the gas-liquid mixer, with a clockwise twist angle of 10 to 90°. The width of the vortex blades gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades that are away from the central shaft of the gas-liquid mixer; and / or, The ratio of the length of the vortex blade to the diameter of the clockwise vortex assembly is 0.5 to 2.0; and / or, In the counterclockwise vortex assembly, 2 to 30 vortex blades are arranged counterclockwise on the outer wall of the central shaft of the gas-liquid mixer, with a counterclockwise twist angle of 10 to 90°. The width of the vortex blades gradually increases from one end to the other. A housing is provided between the ends of two adjacent vortex blades that are away from the central shaft of the gas-liquid mixer; and / or, The ratio of the length of the vortex blade to the diameter of the counterclockwise vortex assembly is 0.5 to 2.

0.

3. The gas-liquid mixer according to claim 2, characterized in that, The end of the clockwise vortex assembly with the larger vortex blade width is connected to the end of the counterclockwise vortex assembly with the smaller vortex blade width; and / or The vortex blade has 1 to 10 1-5 mm vent holes on the end face away from the central axis of the gas-liquid mixer; these vent holes are the ammonia vortex blade inlets; and / or, The inner side of the torsion surface of the vortex blade is provided with small holes with a diameter of 0.1~1.0mm. These small holes are the outlet of the ammonia vortex blade, and there are 1~5 rows of small holes, with 5~20 holes in each row.

4. A microfluidic mixer, characterized in that, The system includes a microfluidic mixer housing, with a material inlet at one end and a material outlet at the other end. An axial microfluidic mixing unit and a radial microfluidic mixing unit are disposed within the housing between the material inlet and the material outlet. The axial microfluidic mixing unit includes a central shaft, on which multiple axial swirl vanes are arranged circumferentially on the outer wall. Each axial swirl vane is composed of 3 to 50 swirl vanes connected along the axis. The radial microfluidic mixing unit consists of 5 to 20 layers of radial swirl vanes arranged alternately, initially arranged uniformly or randomly in any direction. Each layer of radial swirl vanes is composed of 2 to 10 swirl vanes arranged radially and connected sequentially.

5. The microfluidic mixer according to claim 4, characterized in that, Multiple axial swirl vanes are arranged circumferentially along the tangential direction or along the central direction.

6. The microfluidic mixer according to claim 5, characterized in that, The twist angle of a single swirl unit plate is 180°~360°, and the ratio of the length of a single swirl unit plate after twisting to the maximum diameter of an axial swirl plate is 1~5; and / or, The maximum diameter of an axial swirl vane is 0.05 to 0.2 times the inner diameter of the microfluidic mixer housing.

7. The microfluidic mixer according to claim 6, characterized in that, The twist angle of a single swirl unit plate is 180°~360°, and the ratio of the length of a single swirl unit plate after twisting to the maximum diameter of a layer of radial swirl plates is 1~5; and / or, The ratio of the diameter of one radial swirl vane to the inner diameter of the microfluidic mixer shell is 0.05~0.

2.

8. An online ammoniation device for polyacrylonitrile spinning solution, characterized in that, It includes a degassing device, a degassing gear pump, a gas-liquid mixer as described in any one of claims 1-3, a microfluidic mixer as described in any one of claims 4-7, a material storage mixing vessel, a spinning gear pump, and a filter, connected in sequence.

9. The online ammoniation device for polyacrylonitrile spinning solution according to claim 8, characterized in that, Multiple gas-liquid mixers are connected in series; and / or, Multiple microfluidic mixers are connected in series.

10. The online ammoniation device for polyacrylonitrile spinning solution according to claim 9, characterized in that, The gas-liquid mixers are arranged in series, with 1 to 10 units; and / or, The microfluidic mixers are arranged in series in 2 to 10 units.

11. The online ammoniation device for polyacrylonitrile spinning solution according to claim 8, characterized in that, The storage mixing vessel includes a storage mixing vessel body, and a stirring rod is arranged along the axial direction inside the storage mixing vessel body.

12. The online ammoniation device for polyacrylonitrile spinning solution according to claim 11, characterized in that, The stirring rod is provided with an upper layer blade, a middle layer blade, a lower layer blade, and a lower center blade in sequence from top to bottom.

13. The online ammoniation device for polyacrylonitrile spinning solution according to claim 12, characterized in that, The diameter of the upper and middle impellers is 0.7 to 0.95 times the inner diameter of the storage mixing vessel; and / or, The upper blades and the middle blades are arranged alternately, and the axes of the upper blades and the middle blades are perpendicular to each other in the same plane; and / or, The diameter of the lower impeller is 0.9 to 0.98 times the inner diameter of the storage mixing vessel; and / or, The diameter of the lower central impeller is 0.4 to 0.6 times the inner diameter of the storage mixing vessel; and / or, The lower blades and the lower center blades are arranged alternately, and the axes of the lower blades and the lower center blades are perpendicular to each other in the same plane.

14. The online ammoniation device for polyacrylonitrile spinning solution according to claim 12, characterized in that, A broken threaded strip is provided between the middle blade and the lower blade; and / or, An arc-shaped blade is provided between the lower blade and the lower center blade.

15. The online ammoniation device for polyacrylonitrile spinning solution according to claim 11, characterized in that, The top of the storage mixing vessel is provided with a raw liquid inlet, and a raw liquid inlet pipe is inserted into the raw liquid inlet. The raw liquid inlet pipe is located at one end of the storage mixing vessel body near the stirring rod.

16. The online ammoniation device for polyacrylonitrile spinning solution according to claim 15, characterized in that, The raw liquid feed pipe is located at one end of the storage mixing vessel body, 10-50 mm away from the stirring rod.

17. The online ammoniation device for polyacrylonitrile spinning solution according to claim 15, characterized in that, The upper part of the stirring rod is provided with a liquid limiting ring, which is located below the end of the raw liquid feed pipe. The upper opening of the liquid limiting ring is larger, with a diameter of 1 / 10 to 1 / 5 of the inner diameter of the storage mixing vessel body, and the lower opening is smaller, with a diameter of 1 / 8 to 1 / 2 of the upper opening diameter.

18. The online ammoniation device for polyacrylonitrile spinning solution according to claim 17, characterized in that, The length of the liquid-limiting ring is 0.5 to 2.0 times the diameter of the upper opening, and the annular gap width between the lower opening of the liquid-limiting ring and the stirring rod is 1 to 10 mm.

19. A method for online amination of polyacrylonitrile spinning solution, characterized in that, The polyacrylonitrile spinning solution is ammoniated using the online ammoniation device according to any one of claims 8-18; the method is as follows: The polyacrylonitrile spinning solution in the degassing device enters the gas-liquid mixer through the degassing gear pump. The spinning solution is divided into multiple swirling streams by the vortex blades. At the same time, ammonia gas enters the gas chamber through the first ammonia inlet and the second ammonia inlet. The ammonia gas entering the gas chamber enters the hollow structure of the vortex blade through the ammonia vortex blade inlet, and then flows out from the ammonia vortex blade outlet. The outflowing ammonia gas mixes with the spinning solution through counterclockwise and / or clockwise vortexes and then enters the microfluidic mixer. The gas-liquid mixture is divided into multiple microfluids in the axial microfluidic mixing unit and the radial microfluidic mixing unit. The microfluids flow radially, tangentially and axially. After passing through multiple sets of microfluidic mixers, the mixture is continuously divided into multiple microfluids and then mixed and divided to achieve full mixing. The mixture then flows into the storage mixing tank. Under the stirring action of the storage mixing tank, the homogeneity is improved and air bubbles are not entrained. After passing through the spinning gear pump and filter, it is used for stable spinning.

20. The online amination method for polyacrylonitrile spinning solution according to claim 19, characterized in that, The ratio of the ammonia molar flow rate at the first ammonia inlet to the ammonia molar flow rate at the second ammonia inlet is 1~9:1; and / or, The ammonia gas temperature range is 20~40℃; and / or, The gas velocity of ammonia at the outlet of the ammonia vortex blades ranges from 0.001 to 0.01 m / s; and / or, The polyacrylonitrile spinning solution has a temperature range of 40~70℃; and / or, The flow velocity of the spinning solution within the empty tubes of the gas-liquid mixer and microfluidic mixer ranges from 0.01 to 0.1 m / s; and / or, The ratio of the molar amount of ammonia to the molar amount of carboxyl groups in itaconic acid in the polyacrylonitrile spinning solution ranges from 0.1 to 1.0; and / or, The pH value of the spinning solution after ammonia treatment is controlled within the range of 8.0~10; and / or, The stirring speed range of the storage mixing vessel is 1~60 rpm; and / or, The liquid level in the storage mixing vessel is lower than that at the raw liquid inlet, and is 0.1 to 0.8 times the height of the storage mixing vessel.

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