Spinning solution degassing system

Abstract

This invention provides a degassing system for spinning solutions, comprising an intermittent static degassing vessel with a degassing inlet pipe and a degassing outlet pipe. The degassing inlet pipe is connected to the outlet of a polymerization solution degassing vessel. A continuous dynamic degassing pipe is connected to the inlet pipe. The first port of the continuous dynamic degassing pipe is connected to the outlet of the degassing vessel, and the second port is connected to the inlet pipe. A packing layer is provided inside the continuous dynamic degassing pipe. The spinning solution entering the first port falls through the packing layer to the second port. The intermittent static degassing vessel and the continuous dynamic degassing pipe are in a vacuum environment. This invention effectively overcomes the shortcomings of the existing degassing process, which is time-consuming and inefficient, and greatly reduces the production cost of the degassing system.

Description

Technical Field

[0001] This invention belongs to the field of spinning solution degassing technology, specifically relating to a spinning solution degassing system. Background Technology

[0002] During the polymerization process, a large number of bubbles inevitably form in the spinning solution due to factors such as initiator decomposition, mechanical stirring, and desizing processes. These bubbles lead to increased yarn breakage and even yarn breakage during spinning, reducing the production efficiency and performance of the yarn. Therefore, the quality of the spinning solution directly affects the yarn production in the spinning process.

[0003] In the intermittent production process of spinning dope, the raw materials undergo polymerization and negative pressure degassing to initially form a spinning dope with stable performance indicators. However, the large number of air bubbles present in the spinning dope needs to be removed in a degassing tank before the dope can be used for yarn production. In the degassing tank, the spinning dope is left to stand for 3-5 days under negative pressure vacuum conditions and at a certain temperature. During this standing period, the number of air bubbles in the dope gradually decreases. However, the degassing efficiency is affected by the temperature, viscosity, degassing pressure, and degassing time of the dope. Air bubbles in the spinning dope cannot be completely removed, and the standing time required for degassing is long, resulting in low production efficiency for dope spinning. Furthermore, existing technologies for improving degassing efficiency often involve modifying the specific structure of the degassing tank. However, since degassing tanks are generally large, modifying their internal structure is costly. Summary of the Invention

[0004] Therefore, the present invention provides a degassing system for spinning solutions to solve the problems in related technologies where the degassing solution is left to stand in a degassing kettle, resulting in incomplete removal of air bubbles and a long standing time required for degassing, low production efficiency of spinning solution, and high improvement costs due to modifications to the internal structure of the degassing kettle.

[0005] To address the aforementioned problems, this invention provides a spinning solution degassing system, comprising an intermittent static degassing vessel. The intermittent static degassing vessel has a degassing inlet pipe and a degassing outlet pipe. The degassing inlet pipe is connected to the outlet of a polymerization solution degassing vessel. A continuous dynamic degassing pipe is connected to the degassing inlet pipe. The first port of the continuous dynamic degassing pipe is connected to the outlet of the degassing vessel, and the second port of the continuous dynamic degassing pipe is connected to the degassing inlet pipe. A packing layer is provided inside the continuous dynamic degassing pipe. The spinning solution entering the first port falls to the second port through the packing layer. The intermittent static degassing vessel and the continuous dynamic degassing pipe are in a vacuum environment.

[0006] In some embodiments, the continuous dynamic degassing tube includes a cylindrical section assembled with the packing layer, the diameter of the cylindrical section being D, and the flow rate of the spinning solution entering the first port being Q, where Q < (πνD). 2 ) / 4, where ν is the flow velocity of the spinning solution at the filler layer under the action of gravity.

[0007] In some embodiments, 0.4m≤D≤1m; and / or, the maximum diameter of the vessel body of the intermittent static degassing vessel is d, 2m≤d≤5m.

[0008] In some embodiments, the tube body of the continuous dynamic degassing tube further includes a tube cap section detachably connected to a first end of the cylindrical section and a tube bottom section detachably connected to a second end of the cylindrical section. A perforated plate is provided at the port of the cylindrical section facing the tube bottom section, and the filler layer is contained in the perforated plate.

[0009] In some embodiments, a first pivot is provided between the first end of the wall of the cylindrical segment and the cap segment, and a second pivot is provided between the second end of the wall of the cylindrical segment and the bottom segment. The first pivot and the second pivot are coaxially arranged. After the cylindrical segment is disassembled from the cap segment and the bottom segment, it can be rotated around the first pivot and moved out of the gap area between the cap segment and the bottom segment.

[0010] In some embodiments, a flow regulating valve is provided on the pipeline between the outlet of the desiccant and the first port.

[0011] In some embodiments, the outside of the continuous dynamic degassing tube is wrapped with a temperature control component for adjusting the solution temperature inside the continuous dynamic degassing tube.

[0012] In some embodiments, the solution temperature inside the continuous dynamic degassing tube is 40–60°C.

[0013] In some embodiments, the environmental pressure inside the continuous dynamic degassing tube is 10–60 kPaA.

[0014] In some embodiments, the defoaming outlet pipe can be switched on and off with the spinning device.

[0015] This invention provides a spinning solution degassing system. A continuous dynamic degassing tube is added to the pipeline before the intermittent static degassing reactor in existing technologies. The packing layer inside the tube increases the specific surface area of ​​the spinning solution flowing through it. Under the combined effect of the vacuum environment inside the tube, most of the bubbles generated by stirring in the polymerization degassing reactor in the spinning solution flowing into the intermittent static degassing reactor are removed. The spinning solution with most of the bubbles removed can then be further degassed in the subsequent intermittent static degassing reactor. This effectively overcomes the shortcomings of existing technologies, such as long degassing processes and low efficiency. Of course, under some conditions, the spinning solution after degassing treatment by the continuous dynamic degassing tube can also be directly used. The spinning process using the spinning solution further improves spinning efficiency and production capacity. Furthermore, it's important to note that improvements in degassing efficiency in existing technologies primarily focus on modifying the internal structure of the existing degassing vessel. Since the inner diameter of the degassing vessel is generally large, the size of components such as the packing material is also large. However, the continuous dynamic degassing tube in this invention performs dynamic and continuous degassing of the spinning solution, so its size does not need to be too large. Only the flow rate and the corresponding improvement in degassing effect need to be considered. There is no need to consider the large volume requirements for static degassing. Therefore, the size of various components, such as the packing layer, can be designed to be relatively small, greatly reducing the production cost of the degassing system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the spinning solution degassing system according to an embodiment of the present invention (the figure shows the polymerization solution degassing vessel), and the arrows in the figure indicate the flow direction of the spinning solution;

[0017] Figure 2 for Figure 1 A schematic diagram of the internal structure of the continuous dynamic degassing tube.

[0018] Figure label:

[0019] 1. Intermittent static degassing kettle; 11. Degassing inlet pipe; 12. Degassing outlet pipe; 2. Polymerization liquid degassing kettle; 21. Degassing kettle outlet; 22. Degassing kettle inlet; 23. Stirrer; 31. Continuous dynamic degassing pipe; 311. Cylindrical section; 312. Pipe cap section; 313. Pipe bottom section; 314. Perforated plate; 32. Packing layer; 33. First port; 34. Second port; 4. Vacuum port. Detailed Implementation

[0020] See also Figures 1 to 2As shown, according to an embodiment of the present invention, a spinning solution degassing system is provided, including an intermittent static degassing vessel 1. The intermittent static degassing vessel 1 has a degassing inlet pipe 11 and a degassing outlet pipe 12. The degassing inlet pipe 11 is used to communicate with the degassing outlet 21 of the polymerization solution degassing vessel 2. A continuous dynamic degassing pipe 31 is connected to the degassing inlet pipe 11. The first port 33 of the continuous dynamic degassing pipe 31 is connected to the degassing outlet 21, and the second port 34 of the continuous dynamic degassing pipe 31 is connected to the degassing inlet pipe 11. A packing layer 32 is provided inside the continuous dynamic degassing pipe 31. The spinning solution entering the first port 33 falls to the second port 34 through the packing layer 32. The intermittent static degassing vessel 1 and the continuous dynamic degassing pipe 31 are in a vacuum environment. In this technical solution, a continuous dynamic degassing pipe 31 is added to the pipeline before the intermittent static degassing tank 1 in the existing technology. The packing layer 32 inside the pipe can increase the specific surface area of ​​the spinning solution flowing through it. Under the combined effect of the vacuum environment inside the pipe, most of the bubbles generated by stirring in the polymerization liquid degassing tank 2 in the spinning solution flowing into the intermittent static degassing tank 1 can be removed. The spinning solution with most of the bubbles removed can then be further degassed in the subsequent intermittent static degassing tank 1, effectively overcoming the shortcomings of the long time and low efficiency of the degassing process in the existing technology. Of course, under some working conditions, the spinning solution after degassing by the continuous dynamic degassing pipe 31 can also be directly used for spinning. Efficiency and production capacity are further improved. In addition, it should be noted that the improvement of degassing efficiency in the prior art is mostly aimed at improving the internal structure of the existing degassing vessel. Since the inner diameter of the degassing vessel is generally large (mostly three or four meters or even larger), the size of the packing and other components inside is also large. However, the continuous dynamic degassing tube 31 in this invention performs dynamic and continuous degassing treatment on the spinning solution, so its size does not need to be set too large. Only the flow rate and the corresponding improvement of degassing effect need to be considered. There is no need to consider the large volume requirements required for static degassing. Therefore, the size of each component inside, such as the packing layer 32, can be designed to be relatively small, which greatly reduces the production cost of the degassing system.

[0021] The packing material in the aforementioned packing layer 32 can be Pall rings, stepped rings, or other commonly used materials in the industry.

[0022] It should be noted that the aforementioned continuous dynamic degassing tube 31 of the present invention can objectively serve as a section of the degassing inlet tube 11. Its inner diameter can be approximately equal to, or slightly larger than, the inner diameter of the degassing inlet tube 11. Specifically, the tube body of the continuous dynamic degassing tube 31 includes a cylindrical section 311 assembled with the packing layer 32. The diameter of the cylindrical section is D, and the flow rate of the spinning solution entering the first port 33 is Q (in cubic meters per hour), where Q < (πνD). 2) / 4, ν is the flow rate of the spinning solution under gravity at the filler layer 32, in meters per hour. This flow rate is related to the corresponding temperature to prevent the incoming spinning solution from accumulating above the filler layer 32 and to ensure defoaming efficiency.

[0023] In one specific embodiment, 0.4m≤D≤1m; correspondingly, the maximum diameter of the intermittent static degassing vessel 1 is d, 2m≤d≤5m.

[0024] After prolonged use, the filler layer 32 may develop material clumps due to the viscosity of the spinning solution, blocking solution flow, reducing the specific surface area, and consequently lowering degassing efficiency. Therefore, cleaning is necessary. In existing technologies, due to the large size of the vessel body and the relatively large size of the filler layer 32, cleaning often involves removing and replacing a large amount of filler from the top cover of the vessel or the corresponding maintenance port, as a preferred embodiment. However, because the continuous dynamic degassing tube 31 of this invention has a relatively small tube size and a correspondingly small inlet, traditional filler cleaning methods are difficult to implement. Furthermore, due to the continuous dynamic degassing tube 31 of this invention... The continuous dynamic degassing tube 31 is relatively small in size and weight, allowing it to be designed as a detachable unit. Specifically, the tube body includes a cap section 312 detachably connected to the first end of the cylindrical section 311 and a bottom section 313 detachably connected to the second end of the cylindrical section. A perforated plate 314 is provided at the port of the cylindrical section 311 facing the bottom section 313. The packing layer 32 is housed on the perforated plate 314. The aperture of the perforated plate 314 is selected to prevent leakage of the packing layer 32 while allowing smooth flow of the solution. This allows the cylindrical section to be removed from the continuous dynamic degassing tube 31 when cleaning the packing layer 32 is required, eliminating the need to enter a small space for cleaning, thus improving convenience. Understandably, appropriate sealing components should be designed at both ends of the cylindrical section 311 to prevent solution leakage.

[0025] Furthermore, the first end of the wall of the cylindrical section 311 has a first pivot between it and the cap section 312, and the second end of the wall of the cylindrical section 311 has a second pivot between it and the bottom section 313. The first pivot and the second pivot are coaxially arranged. After the cylindrical section 311 is disassembled from the cap section 312 and the bottom section 313, it can be rotated around the first pivot and moved out of the gap area between the cap section 312 and the bottom section 313. Understandably, when packing cleaning is required, the connection between the two ends of the cylindrical section 311 is first removed. Then, the wall of the cylindrical section 311 is pushed forcefully to expose the cylindrical section 311 and its internal packing layer 32 to the external environment, thus facilitating the cleaning of the packing. After cleaning, new packing is added, and the cylindrical section 311 is pushed in the opposite direction and assembled with the pipe cover section 312 and the pipe bottom section 313 to form a seal. Since the removal and reassembly of the cylindrical section 311 in this technical solution is by rotational pivoting, the alignment and assembly are extremely simple. As a preferred solution, the perforated plate 314 is detachably mounted on the cylindrical section 311. After the cylindrical section 311 is removed, the perforated plate 314 carrying the packing can be removed as a whole, improving replacement efficiency.

[0026] In some embodiments, a flow regulating valve (not shown in the figure) is provided on the pipeline between the despinning kettle outlet 21 and the first port. The flow regulating valve can adjust the amount of spinning solution flowing into the continuous dynamic degassing pipe 31, so as to match the flow of the filling layer 32, and prevent the spinning solution from clogging in the pipe and reducing the degassing effect.

[0027] The outer side of the continuous dynamic degassing tube 31 is wrapped with a temperature control component (not shown in the figure) to adjust the solution temperature inside the continuous dynamic degassing tube 31. The temperature control component can be a structure such as an electric heating wire that can be energized and adjusted in temperature (in some cases, the temperature control component can also cool down). Since the spinning solution flowing out of the polymerization liquid degassing reactor 2 flows into the continuous dynamic degassing tube 31 through the pipeline, the diameter of the pipeline is relatively small. Especially in low temperature environments, the temperature of the spinning solution may drop after flowing into the continuous dynamic degassing tube 31, resulting in an increase in its viscosity, which is not conducive to its dynamic degassing. Based on this purpose, in this application, the internal ambient temperature of the continuous dynamic degassing tube 31 is heated and maintained by the temperature control component, which can ensure a high dynamic degassing effect.

[0028] It is understood that the solvent of the spinning solution in this invention is a dimethyl sulfoxide solution, and the solute is polyacrylonitrile. To ensure that the concentration of the spinning solution exiting the continuous dynamic degassing tube 31 is equal to the concentration of the spinning solution entering the continuous dynamic degassing tube 31, the solution temperature inside the continuous dynamic degassing tube 31 is 40–60°C to prevent the volatilization of the dimethyl sulfoxide solution during the degassing process. The environmental pressure inside the continuous dynamic degassing tube 31 is 10–60 kPaA to further prevent the volatilization of the dimethyl sulfoxide solution during the degassing process. It should be specifically noted that ensuring the solvent does not volatilize means ensuring that the solvent content of the spinning solution does not change, the solute / solvent ratio remains constant, and the performance of the spinning solution is stable.

[0029] Not shown in the figure, the degassing outlet pipe 12 is connected to the spinning device in an on / off manner (controlled by an on / off valve). This on / off connection allows for adjustment of the settling interval time of the intermittent settling degassing kettle 1. As mentioned earlier, in some operating conditions where the quality requirements of the carbon fiber tow are not very high, this settling interval time can be shortened or even reduced to 0.

[0030] It should be noted that, see Figure 1 As shown, the polymerization liquid demonolysis vessel 2 can be a corresponding demonolysis vessel in the prior art, specifically, it also has a demonolysis vessel inlet 22 and a stirrer 23 therein.

[0031] Example 1

[0032] After polymerization, the polyacrylonitrile solution undergoes demonolysis in reactor 2 to form a 20% demonolysis solution (i.e., the aforementioned spinning solution). During the demonolysis process, the solution undergoes mechanical stirring, generating a large number of bubbles. This bubble-laden solution flows through a degassing pipeline (i.e., the aforementioned continuous dynamic degassing pipe 31, hereinafter the same). When the polyacrylonitrile solution temperature is 50℃ and the flow rate is 2m³ / h... 3 / h, the pressure in the degassing pipeline is controlled at 40kPaA by a vacuum device; when the temperature of the polyacrylonitrile solution is 40℃, the flow rate of the polyacrylonitrile solution is 1m³ / h. 3The pressure in the degassing pipeline is controlled at 20 kPa / h using a vacuum device. A polyacrylonitrile solution containing a large number of bubbles (solvent: dimethyl sulfoxide) flows into the degassing pipeline after degassing. Once inside, the polyacrylonitrile solution is distributed within the packing material. During flow, the bubbles are broken and removed under negative pressure. The material flows out of the packing material and falls in filaments to the bottom of the degassing pipeline. The initially degassed polyacrylonitrile solution then goes to the degassing kettle (i.e., the aforementioned intermittent static degassing kettle 1). After all the polyacrylonitrile solution has entered the degassing kettle, a vacuum is created to form a negative pressure condition for further static degassing. The degassing time is shortened from 3-5 days to 1-3 days, resulting in higher degassing efficiency. This method can also remove 95% of the bubbles in the spinning solution (after exiting the continuous dynamic degassing pipe 31). This portion of the spinning solution can achieve complete degassing by standing in the intermittent static degassing kettle 1 for a relatively short time.

[0033] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0034] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above are merely preferred embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A degassing system for spinning solutions, characterized in that, The system includes an intermittent static degassing vessel (1), which has a degassing inlet pipe (11) and a degassing outlet pipe (12). The degassing inlet pipe (11) is used to connect with the degassing outlet (21) of the polymerization liquid degassing vessel (2). A continuous dynamic degassing pipe (31) is connected to the degassing inlet pipe (11). The first port (33) of the continuous dynamic degassing pipe (31) is connected to the degassing outlet (21), and the second port (34) of the continuous dynamic degassing pipe (31) is connected to the degassing inlet pipe (11). A packing layer (32) is provided inside the continuous dynamic degassing pipe (31). The spinning solution entering the first port (33) falls to the second port (34) through the packing layer (32). The intermittent static degassing vessel (1) and the continuous dynamic degassing pipe (31) are in a vacuum environment.

2. The spinning solution defoaming system according to claim 1, characterized in that, The continuous dynamic degassing tube (31) includes a cylindrical section (311) assembled with the packing layer (32), the diameter of the cylindrical section is D, and the flow rate of the spinning solution entering the first port (33) is Q, Q < (πνD). 2 ) / 4, ν is the flow rate of the spinning solution under gravity at the filler layer (32).

3. The spinning solution defoaming system according to claim 2, characterized in that, 0.4m≤D≤1m; and / or, the maximum diameter of the vessel body of the intermittent static degassing vessel (1) is d, 2m≤d≤5m.

4. The spinning solution defoaming system according to claim 2, characterized in that, The tube body of the continuous dynamic degassing tube (31) also includes a tube cap section (312) detachably connected to the first end of the cylindrical section (311) and a tube bottom section (313) detachably connected to the second end of the cylindrical section. A perforated plate (314) is provided at the port of the cylindrical section (311) facing the tube bottom section (313), and the filler layer (32) is filled on the perforated plate (314).

5. The spinning solution degassing system according to claim 4, characterized in that, The first end of the wall of the cylindrical segment (311) has a first pivot between it and the pipe cap segment (312), and the second end of the wall of the cylindrical segment (311) has a second pivot between it and the pipe bottom segment (313). The first pivot and the second pivot are coaxially arranged. After the cylindrical segment (311) is disassembled from the pipe cap segment (312) and the pipe bottom segment (313), it can be rotated around the first pivot and moved out of the interval area between the pipe cap segment (312) and the pipe bottom segment (313).

6. The spinning solution degassing system according to claim 1, characterized in that, A flow regulating valve is provided on the pipeline between the outlet (21) of the desiccant and the first port.

7. The spinning solution degassing system according to claim 1, characterized in that, The outer side of the continuous dynamic degassing tube (31) is wrapped with a temperature control component for adjusting the solution temperature inside the continuous dynamic degassing tube (31).

8. The spinning solution degassing system according to claim 7, characterized in that, The solution temperature inside the continuous dynamic degassing tube (31) is 40-60℃.

9. The spinning solution defoaming system according to claim 1, characterized in that, The internal environmental pressure of the continuous dynamic degassing tube (31) is 10-60 kPaA.

10. The spinning solution degassing system according to claim 1, characterized in that, The defoaming outlet pipe (12) can be switched on and off with the spinning device.

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