Polyacrylonitrile fiber steam drafting device and drafting control method

Abstract

The application provides a polyacrylonitrile fiber steam drafting device and a drafting control method. The drafting device comprises a silencer pipe, a sealed pressure reduction pipe, a preheating pipe and a drafting pipe. The silencer pipe comprises a silencer section, and the silencer section comprises three layers of pipes. The innermost layer is a porous honeycomb pipe, the middle layer is a foamed nickel layer, and the outermost layer is a stainless steel pipe. According to the application, the noise can be effectively reduced to below 80 decibels, the normal and reliable operation of the drafting process is ensured, and the structure of the innermost layer and the outermost layer can further enhance the structural strength of the silencer section. Through the matching and cooperation of different specifications of sealing rings and fiber production processes, the prepared fiber has a smooth appearance without hair, is convenient, safe and efficient to wear, is suitable for different numbers of spinning positions, can improve the drafting effect of the fiber and the quality of the polyacrylonitrile fiber.

Description

Technical Field

[0001] This invention relates to the field of polyacrylonitrile-based carbon fiber production technology, specifically to a polyacrylonitrile fiber steam drawing device and drawing control method. Background Technology

[0002] Carbon fiber is a material with excellent properties such as high strength, high modulus, low density, fatigue resistance, and high temperature resistance, and is widely used in military and civilian fields. Polyacrylonitrile fiber, also known as the precursor fiber of polyacrylonitrile-based carbon fiber, is the raw material fiber for manufacturing polyacrylonitrile-based carbon fiber, and its quality directly affects the quality of polyacrylonitrile-based carbon fiber. The most widely used methods for preparing precursor fibers are wet spinning and dry-jet wet spinning. The process mainly includes coagulation bath, water washing, hot water drawing, oiling, drying and densification, steam drawing, and winding. Among them, steam drawing uses saturated steam as the drawing medium and is carried out in a high-pressure steam drawing device. The high-pressure steam drawing device is the key equipment for producing high-quality polyacrylonitrile fibers and achieving high strength and fine denier polyacrylonitrile fibers.

[0003] CN106906527A discloses a steam pressure drawing device for large-tow multi-spinning positions of polyacrylonitrile fibers. The device comprises a first silencing chamber, a first depressurization chamber, a first preheating chamber, a second depressurization chamber, a drawing chamber, a third depressurization chamber, a second preheating chamber, a fourth depressurization chamber, and a second silencing chamber, connected sequentially. Under the action of the sealing components and chambers, the pressure and temperature increase in a stepwise manner, ensuring thorough and uniform preheating of the large filaments before drawing. This enables rapid and high-ratio drawing of large filaments and is applicable to the spinning process of large-tow polyacrylonitrile precursor fibers. However, it is suitable for simultaneous drawing of 20 or fewer filaments at each spinning position, resulting in low production efficiency. The steam drawing furnace has a relatively low pressure and a long and complicated structure, making the threading process time-consuming and labor-intensive, which is not conducive to operation. CN104278459A proposes a high-pressure steam drawing device for polyacrylonitrile-based carbon fiber precursors, which includes a high-pressure steam drawing chamber and a labyrinth sealing chamber located at the end of the high-pressure steam drawing chamber. The labyrinth sealing chamber is composed of two openable upper and lower boxes. When the box is closed, the upper and lower plates of the same level are sealed and fastened. The same level notches of the upper and lower plates form a channel that can accommodate the fiber bundle. This invention has poor pressure holding effect in the steam drawing chamber, which is not conducive to fiber plasticization and drawing.

[0004] Because existing technologies for steam drawing of polyacrylonitrile fibers suffer from technical problems such as excessive noise, this invention studies and designs a steam drawing device and drawing control method for polyacrylonitrile fibers. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of excessive noise in the steam drawing of polyacrylonitrile fibers in the prior art, thereby providing a steam drawing device and drawing control method for polyacrylonitrile fibers.

[0006] To address the above problems, the present invention provides a polyacrylonitrile fiber steam drawing device, comprising:

[0007] The silencing pipe includes a silencing section, which comprises three layers of circular pipes: the innermost layer is a porous honeycomb circular pipe, the middle layer is a foam nickel layer for the silencing section, and the outermost layer is a stainless steel circular pipe.

[0008] In some implementations...

[0009] The muffler pipe also includes an exhaust section connected to the muffler section. The exhaust section is a rectangular tube structure with a rectangular cross-section. The uppermost layer of the exhaust section is a removable cover plate, and the lowermost layer is a porous stainless steel plate. The middle layer between the removable cover plate and the porous stainless steel plate is a rectangular wire bundle channel. The outermost layers on both sides of the horizontal direction of the exhaust section are exhaust section stainless steel plates, and the inner wall is adhered with a foam nickel lay-up.

[0010] In some implementations...

[0011] A PTFE gasket is also provided on the inner side of the uppermost removable cover plate of the exhaust section, i.e., on the side in contact with the rectangular tube, and the exhaust section is also connected to a steam exhaust pipe.

[0012] In some implementations...

[0013] The muffler includes muffler I and muffler II. Muffler I includes a muffler section and an exhaust section connected to each other. Muffler II includes a muffler section and an exhaust section connected to each other. Both muffler section I and muffler section II include three layers of circular tubes: the innermost layer is a porous honeycomb circular tube, the middle layer is a foam nickel layer, and the outermost layer is a stainless steel circular tube.

[0014] In some implementations...

[0015] Both the exhaust section of muffler pipe I and the exhaust section of muffler pipe II are rectangular tube structures with a rectangular cross-section. The structural form of both is as follows: the uppermost layer is a removable cover plate, the lowermost layer is a porous stainless steel plate, the middle layer between the removable cover plate and the porous stainless steel plate is a rectangular wire bundle channel, the outermost layer on both sides in the horizontal direction is the exhaust section stainless steel plate, and the inner wall is adhered with a foam nickel lay-up.

[0016] In some implementations...

[0017] The muffler I exhaust section is also connected to a first exhaust pipe, the muffler II exhaust section is also connected to a second exhaust pipe, the stretching pipe is also connected to an intake pipe, and the intake pipe is equipped with a switch valve.

[0018] In some implementations...

[0019] The polyacrylonitrile fiber steam drawing device has an axial direction. The sealed pressure reducing pipe includes a sealed pressure reducing pipe I, a sealed pressure reducing pipe II, and a sealed pressure reducing pipe III. Their structures are arranged sequentially along the axial direction as follows: the silencer pipe I, the sealed pressure reducing pipe I, the preheating pipe, the sealed pressure reducing pipe II, the drawing pipe, the sealed pressure reducing pipe III, and the silencer pipe II. One end of the exhaust section of the silencer pipe I is connected to the silencer section of the silencer pipe I, and the other end of the exhaust section of the silencer pipe I is connected to the sealed pressure reducing pipe I. One end of the exhaust section of the silencer pipe II is connected to the silencer section of the silencer pipe II, and the other end of the exhaust section of the silencer pipe II is connected to the sealed pressure reducing pipe III.

[0020] In some implementations...

[0021] Sealing rings are provided inside the sealing pressure reducing pipe I, the sealing pressure reducing pipe II, and the sealing pressure reducing pipe III. The wire bundle passes through the silencing section of the silencing pipe I, the exhaust section of the silencing pipe I, the sealing pressure reducing pipe I, the preheating pipe, the sealing pressure reducing pipe II, the drawing pipe, the sealing pressure reducing pipe III, the exhaust section of the silencing pipe II, and the silencing section of the silencing pipe II in sequence. Along the direction in which the wire bundle passes, the inner diameter of the sealing ring in the sealing pressure reducing pipe I, the inner diameter of the sealing ring in the sealing pressure reducing pipe II, and the inner diameter of the sealing ring in the sealing pressure reducing pipe III gradually decrease. That is, the inner diameter of the sealing ring in the sealing pressure reducing pipe III is smaller than the inner diameter of the sealing ring in the sealing pressure reducing pipe II, and the inner diameter of the sealing ring in the sealing pressure reducing pipe II is smaller than the inner diameter of the sealing ring in the sealing pressure reducing pipe I.

[0022] In some implementations...

[0023] Along the aforementioned axial direction, the draw ratio of the drawing tube is 2.5 to 5.5.

[0024] The present invention also provides a method for controlling the stretching of a polyacrylonitrile fiber steam stretching device as described above, comprising:

[0025] The control steps include controlling the steam pressure entering the drawing tube through the air inlet pipe to be 0.2-0.6 MPa, the pressure after being successively reduced by the sealing pressure reducing pipe II and the sealing pressure reducing pipe I to be 0.05-0.35 MPa, and the pressure after being reduced by the sealing pressure reducing pipe III to be 0.05-0.35 MPa; controlling the speed of the filament bundle on the inlet side to be 40-80 m / min and the speed on the outlet side to be 200-400 m / min.

[0026] The polyacrylonitrile fiber steam drawing device and drawing control method provided by the present invention have the following beneficial effects:

[0027] 1. This invention, by configuring the silencer pipe of the polyacrylonitrile steam drawing device into a structure including a silencer section, wherein the silencer section comprises a three-layer circular tube structure, specifically, the innermost layer is a porous honeycomb circular tube, the middle layer is a nickel foam layer (preferably with a nickel foam pore density of 50-100 PPI), and the outermost layer is a stainless steel circular tube with a 360° annular narrow opening channel around its circumference for condensate or water discharge), can effectively reduce noise, lowering the noise at the silencer pipe inlet to below 80 decibels, ensuring the normal and reliable operation of the drawing process. Furthermore, the aforementioned structure of the innermost and outermost layers further enhances the structural strength of the silencer section and effectively removes condensate, improving the fiber drawing effect. This invention further configures the exhaust section of the silencer pipe to be connected to the silencer section, and horizontally... The invention employs a rectangular tube structure with a rectangular cross-section. The uppermost layer of the exhaust section is a removable cover plate, and the lowermost layer is a porous stainless steel plate. The intermediate layer between the uppermost and lowermost layers is a rectangular wire bundle channel. The outermost layers on both sides of the horizontal direction of the exhaust section are stainless steel plates, and the inner wall is adhered with a nickel foam layer. This structure further reduces the noise generated between the gas and the wire bundle during the drawing process, lowering the noise at the silencer nozzle to below 75 decibels. This further solves the problem of excessive noise during the drawing process and ensures the normal and reliable operation of the drawing process. By providing the aforementioned silencer section with at least three layers of circular tubes and a rectangular exhaust section with upper, middle, and lower layers on both sides of the air inlet and outlet, the invention further reduces the noise at both exhaust ends and improves the operational reliability of the drawing process.

[0028] 2. This invention also achieves pressure reduction and sealing by setting the inner diameter of the three specifications of sealing rings in the sealing pressure reducing pipe I, sealing pressure reducing pipe II, and sealing pressure reducing pipe III arranged along the axial direction of the drawing device, and matching them with the running fibers. This results in less heat loss, better drawing effect, convenient and safe threading, and high efficiency. The prepared fibers have a smooth appearance without fuzz and are suitable for production lines with different numbers of spinning positions. The air inlet pipe of the drawing pipe is equipped with a switch valve, and each air inlet pipe controls one spinning position independently. In addition, the drawing control method of this invention, through the matching and coordination of different specifications of sealing rings with the fiber production process, controls the air inlet pressure at 0.2-0.6MPa. After pressure reduction by the sealing pressure reducing pipe, the pressure drops to 0.05-0.35MPa. Furthermore, by controlling the fiber bundle inlet speed of 40-80m / min and the fiber outlet speed of 200-400m / min, the prepared fibers can be made to have a smooth appearance without fuzz and are suitable for production lines with different numbers of spinning positions, improving the fiber bundle drawing effect and the quality of polyacrylonitrile fibers. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the polyacrylonitrile fiber steam drawing device of the present invention.

[0030] Figure 2 This is a schematic diagram of the cross-sectional structure of the silencing section of the silencing pipe in the steam stretching device of the present invention.

[0031] Figure 3 This is a schematic diagram of the cross-sectional structure of the exhaust section of the silencer pipe in the steam stretching device of the present invention.

[0032] The reference numerals in the attached figures are as follows:

[0033] 1. Silencer I; 1-1. Silencer I Silencer Section; 1-2. Silencer I Exhaust Section; 2. Sealed Pressure Reducing Pipe I; 3. Preheating Pipe; 4. Sealed Pressure Reducing Pipe II; 5. Drawing Pipe; 6. Sealed Pressure Reducing Pipe III; 7. Silencer II; 7-1. Silencer II Silencer Section; 7-2. Silencer II Exhaust Section; 8. Exhaust Pipe; 8-1. First Exhaust Pipe; 8-2. Second Exhaust Pipe; 9. Inlet Pipe; 11. Porous Honeycomb Round Pipe; 12. Silencer Section Nickel Foam Layup; 13. Stainless Steel Round Pipe; 14. Exhaust Section Outer Stainless Steel Plate; 15. Porous Stainless Steel Plate; 16. Exhaust Section Nickel Foam Layup; 17. Exhaust Hole. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0037] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0038] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0039] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0040] like Figure 1-3As shown, the present invention provides a polyacrylonitrile fiber steam drawing device, which includes:

[0041] The silencing pipe includes a silencing section, a sealing pressure reducing pipe, a preheating pipe 3, and a drawing pipe 5. The silencing pipe includes a silencing section, which consists of three layers of circular pipes: the innermost layer is a porous honeycomb circular pipe 11, the middle layer is a silencing section foam nickel layer 12, and the outermost layer is a stainless steel circular pipe 13.

[0042] This invention addresses the issue of noise reduction in a polyacrylonitrile steam stretching device. The noise reduction section comprises three layers of circular tubes: an innermost porous honeycomb-shaped tube, a middle layer of nickel foam, and an outermost stainless steel tube. This effectively reduces noise to below 80 decibels at the tube opening, ensuring the normal and reliable operation of the stretching process. Furthermore, the innermost and outermost layers further enhance the structural strength of the noise reduction section.

[0043] In some implementations...

[0044] The muffler also includes an exhaust section connected to the muffler. The exhaust section is a rectangular tube structure with a rectangular cross-section. The uppermost layer of the exhaust section is a removable cover plate, and the lowermost layer is a porous stainless steel plate 15. The middle layer between the uppermost and lowermost layers is a rectangular wire bundle channel. The outermost layers on both sides of the horizontal direction of the exhaust section are exhaust section stainless steel plates 14, and the inner wall is adhered with a foam nickel layer 16 (the middle layer is a hollow structure for the wire bundle to pass through, i.e., a hollow rectangular tube, with a removable cover plate on top, wires running in the middle, a porous stainless steel plate below, and a foam nickel coating layer + stainless steel plate outer layer on the sides).

[0045] The present invention further reduces the noise generated between the gas and the filaments during the drawing process by setting the exhaust section of the silencer pipe to a rectangular tube structure connected to the silencer section. The uppermost layer of the exhaust section is a removable cover plate, the lowermost layer is a porous stainless steel plate, the middle layer between the uppermost and lowermost layers is a rectangular filament channel, and the outermost layers on both sides of the horizontal direction of the exhaust section are exhaust section stainless steel plates with a foam nickel layup adhered to the inner wall. This can further reduce the noise generated between the gas and the filaments during the drawing process, reducing the noise at the silencer pipe opening to below 75 decibels, further solving the problem of high noise during the drawing process, and further ensuring the normal and reliable operation of the drawing process.

[0046] In some implementations...

[0047] A PTFE gasket is also provided on the inner side of the uppermost removable cover plate of the exhaust section, i.e., on the side in contact with the rectangular tube. The exhaust section is also connected to a steam exhaust pipe 8 (the exhaust pipe 8 is connected to the exhaust hole 17 of the muffler exhaust section). This is a further preferred structural form of the present invention. The PTFE gasket provided on the inner side of the upper removable cover plate of the exhaust section can play a sealing role, ensuring that the gas inside the exhaust section will not leak out and will be discharged normally from the steam exhaust pipe at the lower end.

[0048] In some implementations...

[0049] The silencer pipe includes silencer pipe I1 and silencer pipe II7. Silencer pipe I1 includes a connected silencer section 1-1 and a silencer exhaust section 1-2. Silencer pipe II7 includes a connected silencer section 7-1 and a silencer exhaust section 7-2. Both silencer section 1-1 and silencer section 7-1 consist of three layers of circular tubes: the innermost layer is a porous honeycomb circular tube 11, the middle layer is a silencer section foam nickel layer 12, and the outermost layer is a stainless steel circular tube 13. Preferably, the foam nickel has a pore density of 50-100 PPI (Pores Per Linear Inch is a unit of pore density, representing the average number of pores per unit inch). The outermost stainless steel circular tube has a 360° annular narrow opening channel around its circumference for condensate or water drainage.

[0050] This is a further preferred structural form of the muffler of the present invention, namely, a structure including two muffler sections, each muffler section including a muffler section and an exhaust section, and each muffler section including the above-mentioned inner, middle and outer three-layer circular tube structure, which can be adapted to the structure of the middle drawing tube where air flows towards both ends after intake and exhausts towards both ends, which can further reduce the noise at the two exhaust ends and improve the operational reliability of the drawing process.

[0051] In some implementations...

[0052] Both the exhaust section 1-2 of the muffler I and the exhaust section 7-2 of the muffler II are rectangular tube structures with a rectangular cross-section. The structure of both is as follows: the uppermost layer is a detachable cover plate, the lowermost layer is a porous stainless steel plate 15, the middle layer between the detachable cover plate and the porous stainless steel plate 15 is a rectangular wire bundle channel, the outermost layers on both sides in the horizontal direction are exhaust section stainless steel plates 14, and the inner wall is adhered with a foam nickel lay-up layer 16.

[0053] This is a further preferred structural form of the muffler of the present invention, namely, a structure including two muffler sections, each muffler section including a muffler section and an exhaust section, and each exhaust section including the above-mentioned upper, middle and lower three-layer circular tube structure, which can be adapted to the structure of the middle drawing tube after air intake flows to both ends and exhausts to both ends, which can further reduce the noise at the two exhaust ends and improve the operational reliability of the drawing process.

[0054] In some implementations...

[0055] The muffler I exhaust section 1-2 is also connected to a first exhaust pipe 8-1, the muffler II exhaust section 7-2 is also connected to a second exhaust pipe 8-2, the stretching pipe 5 is also connected to an intake pipe 9, and the intake pipe 9 is equipped with a switch valve.

[0056] The steam exhaust pipe 8 of the present invention includes and Figure 1 The first exhaust pipe connected to the exhaust section of the muffler pipe I at the left end, and the second exhaust pipe connected to the exhaust section of the muffler pipe II at the right end, achieve the effect of exhausting at both ends. The air intake pipe connected to the drafting pipe can take in air into the drafting device and flow in two directions and exhaust at the muffler pipes at both ends. The air intake pipe of the drafting pipe is equipped with a switch valve, which allows each air intake pipe to control a spinning position independently.

[0057] In some implementations...

[0058] The polyacrylonitrile fiber steam drawing device has an axial direction. The sealed pressure reducing pipe includes a sealed pressure reducing pipe I2, a sealed pressure reducing pipe II4, and a sealed pressure reducing pipe III6. The structure of the sealed pressure reducing pipe III6 is arranged sequentially along the axial direction as follows: the silencer pipe I1, the sealed pressure reducing pipe I2, the preheating pipe 3, the sealed pressure reducing pipe II4, the drawing pipe 5, the sealed pressure reducing pipe III6, and the silencer pipe II7. One end of the exhaust section 1-2 of the silencer pipe I is connected to the silencer section 1-1 of the silencer pipe I, and the other end of the exhaust section 1-2 of the silencer pipe I is connected to the sealed pressure reducing pipe I2. One end of the exhaust section 7-2 of the silencer pipe II is connected to the silencer section 7-1 of the silencer pipe II, and the other end of the exhaust section 7-2 of the silencer pipe II is connected to the sealed pressure reducing pipe III6.

[0059] This is a further preferred structural form of the drafting device of the present invention. By setting the sealing pressure reducing pipe I, sealing pressure reducing pipe II, and sealing pressure reducing pipe III along the axial direction of the drafting device, it can play a role in pressure reduction and sealing, resulting in less heat loss and better drafting effect. Furthermore, by matching the specifications of the three types of sealing rings with the drafting process and the fiber filling rate in the sealing rings, the drafting effect is guaranteed, and the threading is convenient, safe, and efficient. It reduces fiber breakage and fuzz caused by sealing rings that are too large or too small, resulting in a smooth and fuzz-free fiber appearance. It is also suitable for production lines with different numbers of spinning positions. The silencer pipe of the present invention is an important improvement. Existing technologies only have the part opposite to the exhaust section of the silencer pipe of the present invention, and do not have the silencer section of the silencer pipe of the present invention. The present invention, through the three-layer circular pipe structure of the silencer pipe silencer section, can achieve an effective noise reduction effect, with a significant noise reduction effect.

[0060] The polyacrylonitrile fiber steam drawing device of the present invention includes a silencer pipe I, a sealed pressure reducing pipe I, a preheating pipe, a sealed pressure reducing pipe II, a drawing pipe, a sealed pressure reducing pipe III, and a silencer pipe II. The silencer pipes I and II are located at the fiber inlet and fiber outlet ports of the steam drawing device. Each silencer pipe includes a silencer section and an exhaust section (exhaust + liquid drainage). The silencer section is a three-layer circular pipe: the innermost layer is a porous honeycomb circular pipe; the middle layer is a nickel foam layer, preferably with a pore density of 50-100 PPI; and the outermost layer is a stainless steel circular pipe, preferably with a 360° annular narrow opening channel around its circumference for condensate or water drainage. The exhaust section is a rectangular pipe, with a removable cover plate and PTFE gasket at the top, a porous stainless steel plate at the bottom connected to a steam exhaust pipe, and a rectangular fiber bundle channel in the middle. Nickel foam layers are present on both sides, further reducing the noise at the silencer pipe inlet to <75 decibels.

[0061] The preheating pipe of the present invention is connected to the sealing pressure reducing pipes on both sides and is a hollow round pipe.

[0062] The drawing tube of the present invention is connected in the middle of the sealing pressure reducing pipes on both sides. Preferably, the drawing tube is a round tube with an air inlet pipe at the bottom and a round tube sleeve in the middle. After the steam is depressurized by the pressure reducing valve, it enters the jacketed tube from the air inlet pipe at the bottom of the drawing tube and is discharged from the exhaust section of the silencer pipe.

[0063] The preheating tube, sealing pressure reducing tube, and drawing tube of the present invention are preferably stainless steel tubes, wrapped with an aerogel felt insulation layer, and the outermost layer is an aluminum foil layer. High-pressure steam enters from the drawing tube, and the steam pressure in the drawing tube is 2-6 kg (0.2-0.6 MPa). After being depressurized by the sealing pressure reducing tube, the pressure drops to 0.5-3.5 kg (0.05-0.35 MPa).

[0064] Table 1 Noise detection results of the present invention and prior art

[0065]

[0066] Appendix 1 Notes: Sample 1: Noise detection results in the prior art; Sample 2: Noise detection results in the present invention. In some embodiments,

[0067] Sealing rings are provided inside the sealing pressure reducing pipe I2, the sealing pressure reducing pipe II4, and the sealing pressure reducing pipe III6. A wire bundle passes sequentially through the silencing section 1-1 of the silencing pipe I, the exhaust section 1-2 of the silencing pipe I, the sealing pressure reducing pipe I2, the preheating pipe 3, the sealing pressure reducing pipe II4, the drawing pipe 5, the sealing pressure reducing pipe III6, the exhaust section 7-2 of the silencing pipe II, and the silencing section 7-1 of the silencing pipe II. Along the direction of the wire bundle's passage, the inner diameter of the sealing ring in the sealing pressure reducing pipe I2, the sealing ring in the sealing pressure reducing pipe II4, and the sealing ring in the sealing pressure reducing pipe III6 gradually decreases. That is, the inner diameter of the sealing ring in the sealing pressure reducing pipe III6 is smaller than the inner diameter of the sealing ring in the sealing pressure reducing pipe II4, which is smaller than the inner diameter of the sealing ring in the sealing pressure reducing pipe I2. Further preferably, the difference between the inner diameter of the inner sealing ring of the sealing pressure reducing tube I2 and the inner diameter of the inner sealing ring of the sealing pressure reducing tube II4 is ≤3mm, and the difference between the inner diameter of the inner sealing ring of the sealing pressure reducing tube II4 and the inner diameter of the inner sealing ring of the sealing pressure reducing tube III6 is ≤2mm. Preferably, the filling rate of the fiber through the inner hole of the inner sealing ring of the sealing pressure reducing tube I2 is greater than 5% and less than 10%.

[0068] In the sealing pressure reducing tubes I, II, and III of the present invention, sealing components are arranged in sequence. A circular hole is provided in the center of the sealing component. The wire bundle passes through the circular hole in the center of the sealing component. The hole size of the sealing component decreases step by step to ensure normal backward stretching and normal stretching in the stretching tube 5.

[0069] The present invention also provides a method for controlling the stretching of a polyacrylonitrile fiber steam stretching device as described above, comprising:

[0070] The control steps include controlling the steam pressure entering the drawing tube 5 through the air inlet pipe 9 to be 0.2-0.6 MPa, the pressure after being successively reduced by the sealing pressure reducing pipe II4 and the sealing pressure reducing pipe I2 to be 0.05-0.35 MPa, and the pressure after being reduced by the sealing pressure reducing pipe III6 to be 0.05-0.35 MPa; controlling the speed of the filament bundle on the inlet side to be 40-80 m / min and the speed on the outlet side to be 200-400 m / min.

[0071] Preferably, along the aforementioned axial direction, the draw ratio of the draw tube 5 is 2.5 to 5.5 (the draw ratio refers to the ratio of the speed of the drive roller after steam draw to the speed of the drive roller before steam draw).

[0072] The drafting control method of the present invention controls the inlet air pressure at 0.2-0.6 MPa, reduces the pressure after depressurization by a sealing pressure reducing ring to 0.05-0.35 MPa, and controls the fiber bundle inlet speed at 40-80 m / min and outlet speed at 200-400 m / min. This results in a smooth, fuzz-free fiber appearance and is applicable to production lines with different spinning positions, thus improving the quality of polyacrylonitrile fiber drafted bundles.

[0073] Example 1

[0074] The specific steps for preparing T700S-12K polyacrylonitrile fiber in this embodiment are as follows:

[0075] After being dried and densified, polyacrylonitrile fibers are steam-drawn and then wound into a shaft.

[0076] The noise level at the steam stretching silencer pipe opening is 70 decibels.

[0077] The orifice diameters of the sealing components in sealing pressure reducing pipes I, II, and III are 10 / 7 / 6 mm, respectively.

[0078] The speed on the yarn infeed side is 70 m / min, and the speed on the yarn outfeed side is 250 m / min.

[0079] The steam pressure in the drawing tube is 5.5 kg, the drawing depth in the preheating section is 1.0, and the drawing depth in the drawing section is 3.57.

[0080] The wound fibers have a smooth appearance and are free of fuzz.

[0081] Example 2

[0082] The specific steps for preparing T800S-12K polyacrylonitrile fiber in this embodiment are as follows:

[0083] After being dried and densified, polyacrylonitrile fibers are steam-drawn and then wound into a shaft.

[0084] The noise level at the steam stretching silencer pipe opening is 65 decibels.

[0085] The orifice diameters of the sealing components in sealing pressure reducing pipes I, II, and III are 9 / 7 / 5 mm, respectively.

[0086] The speed on the yarn infeed side is 60 m / min, and the speed on the yarn outfeed side is 300 m / min.

[0087] The steam pressure in the drawing tube is 6 kg, the preheating section has a drawing ratio of 1.0, and the drawing section has a drawing ratio of 5.0.

[0088] The wound fibers have a smooth appearance and are free of fuzz.

[0089] The polyacrylonitrile fiber steam drawing device and drawing control method provided by this invention can control the steam switch at a single spinning station, resulting in minimal heat loss, good drawing effect, low noise, convenient threading, and high safety and efficiency. The prepared fibers have a smooth, lint-free appearance and excellent performance. It is applicable to production lines with varying numbers of spinning stations. The above description is merely a preferred embodiment of this invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention. The above description is only a preferred embodiment of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the technical principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A polyacrylonitrile fiber steam drawing device, characterized in that: include: The silencer includes a silencing pipe, a sealing pressure reducing pipe, a preheating pipe (3) and a stretching pipe (5), wherein the silencing pipe includes a silencing section, the silencing section includes three layers of round pipes, the innermost layer is a porous honeycomb round pipe (11), the middle layer is a silencing section foam nickel layer (12), and the outermost layer is a stainless steel round pipe (13). The muffler also includes an exhaust section, which is connected to the muffler. The exhaust section is a rectangular tube structure with a rectangular cross-section. The uppermost layer of the exhaust section is a removable cover plate, and the lowermost layer is a porous stainless steel plate (15). The middle layer between the removable cover plate and the porous stainless steel plate (15) is a rectangular wire bundle channel. The outermost layers on both sides of the horizontal direction of the exhaust section are exhaust section stainless steel plates (14), and the inner wall is adhered with a foam nickel layer (16). The muffler includes muffler I (1) and muffler II (7). Muffler I (1) includes a muffler section (1-1) and an exhaust section (1-2) connected to each other. Muffler II (7) includes a muffler section (7-1) and an exhaust section (7-2) connected to each other. Both muffler section I (1-1) and muffler section II (7-1) include three layers of round pipes. The innermost layer is a porous honeycomb round pipe (11), the middle layer is a muffler section foam nickel layer (12), and the outermost layer is a stainless steel round pipe (13). Both the exhaust section I (1-2) and the exhaust section II (7-2) of the muffler pipe are rectangular tube structures with a rectangular cross-section. The structure of both is as follows: the uppermost layer is a detachable cover plate, the lowermost layer is a porous stainless steel plate (15), the middle layer between the detachable cover plate and the porous stainless steel plate (15) is a rectangular wire bundle channel, the outermost layer on both sides in the horizontal direction is an exhaust section stainless steel plate (14), and the inner wall is adhered with a foam nickel layer (16).

2. The polyacrylonitrile fiber steam drawing device according to claim 1, characterized in that: The inner side of the uppermost removable cover plate of the exhaust section, i.e. the side in contact with the rectangular tube, is also provided with a PTFE gasket, and the exhaust section is also connected to a steam exhaust pipe (8).

3. The polyacrylonitrile fiber steam drawing device according to claim 1, characterized in that: The muffler I exhaust section (1-2) is also connected to a first exhaust pipe (8-1), the muffler II exhaust section (7-2) is also connected to a second exhaust pipe (8-2), the stretching pipe (5) is also connected to an air intake pipe (9), and a switch valve is provided on the air intake pipe (9).

4. The polyacrylonitrile fiber steam drawing device according to claim 3, characterized in that: The polyacrylonitrile fiber steam drawing device has an axial direction. The sealed pressure reducing pipe includes a sealed pressure reducing pipe I (2), a sealed pressure reducing pipe II (4), and a sealed pressure reducing pipe III (6). The structure of the sealed pressure reducing pipe III is arranged in sequence along the axial direction as follows: the silencer pipe I (1), the sealed pressure reducing pipe I (2), the preheating pipe (3), the sealed pressure reducing pipe II (4), the drawing pipe (5), the sealed pressure reducing pipe III (6), and the silencer pipe II (7). One end of the exhaust section (1-2) of the silencer pipe I is connected to the silencer section (1-1) of the silencer pipe I, and the other end of the exhaust section (1-2) of the silencer pipe I is connected to the sealed pressure reducing pipe I (2). One end of the exhaust section (7-2) of the silencer pipe II is connected to the silencer section (7-1) of the silencer pipe II, and the other end of the exhaust section (7-2) of the silencer pipe II is connected to the sealed pressure reducing pipe III (6).

5. The polyacrylonitrile fiber steam drawing device according to claim 4, characterized in that: Sealing rings are provided inside the sealed pressure reducing pipe I (2), the sealed pressure reducing pipe II (4), and the sealed pressure reducing pipe III (6). The wire bundle passes through the silencer section (1-1) of the silencer pipe I, the exhaust section (1-2) of the silencer pipe I, the sealed pressure reducing pipe I (2), the preheating pipe (3), the sealed pressure reducing pipe II (4), the drawing pipe (5), the sealed pressure reducing pipe III (6), the exhaust section (7-2) of the silencer pipe II, and the silencer section (7-1) of the silencer pipe II in sequence. However, along the direction in which the filaments pass through, the inner diameter of the sealing ring in the sealing pressure reducing tube I (2), the inner diameter of the sealing ring in the sealing pressure reducing tube II (4), and the inner diameter of the sealing ring in the sealing pressure reducing tube III (6) gradually decrease. That is, the inner diameter of the sealing ring in the sealing pressure reducing tube III (6) is smaller than the inner diameter of the sealing ring in the sealing pressure reducing tube II (4), and the inner diameter of the sealing ring in the sealing pressure reducing tube II (4) is smaller than the inner diameter of the sealing ring in the sealing pressure reducing tube I (2).

6. The polyacrylonitrile fiber steam drawing device according to claim 4, characterized in that: Along the axial direction, the draw ratio of the drawing tube (5) is 2.5 to 5.

5.

7. A method for controlling the stretching of a polyacrylonitrile fiber steam stretching apparatus as described in any one of claims 4-6, characterized in that: include: The control steps are as follows: the steam pressure entering the drawing tube (5) through the air inlet pipe (9) is controlled to be 0.2~0.6MPa, the pressure after being successively reduced by the sealing pressure reducing pipe II (4) and the sealing pressure reducing pipe I (2) is 0.05~0.35MPa, and the pressure after being reduced by the sealing pressure reducing pipe III (6) is 0.05~0.35MPa; the speed of the filament bundle on the inlet side is controlled to be 40-80m / min, and the speed on the outlet side is controlled to be 200-400m / min.

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