Multi-stage gradient heating and airflow optimization structure of dry spinning nozzle

Abstract

The application discloses a multi-section gradient heating and airflow optimization structure of a dry spinning duct, comprising a vertically arranged duct body, a flow guide system arranged on the inner wall of the duct body, a flow stabilizing device arranged at the air inlet of the duct body, a gas collecting hood arranged at the top of the duct body, and a spinneret installed below the gas collecting hood; the duct body is sequentially provided with a preheating section, a main volatilization section and a setting section along the spinning direction; the inner walls of the preheating section, the main volatilization section and the setting section are all provided with independently controllable heating plates; and the air inlets are respectively arranged on the lower sides of the sections of the duct body. The multi-section gradient heating and airflow optimization structure of the dry spinning duct can effectively solve the problems of low spinning efficiency and poor product quality of the existing dry spinning duct.

Description

Technical Field

[0001] This application relates to the technical field of spandex dry spinning equipment, and more specifically, to a multi-stage gradient heating and airflow optimization structure for a dry spinning channel. Background Technology

[0002] Dry spinning is a mature and widely used fiber forming technology that plays a key role in the preparation of various high-performance polymer materials such as polyacrylonitrile, cellulose acetate, and polyurethane elastic fibers. Its core lies in the process where, after the spinning solution is extruded from the spinneret, hot air evaporates the solvent within the spinning tunnel, thereby solidifying and forming the fiber.

[0003] The structural design and operating parameters of the spinning tunnel directly determine the fiber forming quality, production efficiency, and energy consumption. However, traditional dry spinning tunnels often employ a straight or simple design, resulting in a generally short effective contact time between the hot air and the nascent filaments. Due to insufficient contact time, even at higher temperatures, the solvent is difficult to fully evaporate, leading to a generally high solvent residue rate in the spun fibers. To improve spinning efficiency and product quality, existing technologies have attempted to improve the tunnel by increasing the airflow velocity or hot air temperature. However, traditional tunnel designs struggle to effectively control the disturbance of fine filaments by high-speed airflow, easily generating unstable airflow in localized areas, causing severe vibration of the high-speed filaments. This filament vibration not only increases the formation of fuzz on the fiber surface but also easily leads to fatigue fracture of the filaments under high-frequency vibration, significantly increasing the breakage rate of the production line. Increasing the hot air temperature results in significant energy waste and increases production costs considerably. Summary of the Invention

[0004] The technical problem to be solved by this application is to provide a multi-segment gradient heating and airflow optimization structure for a dry spinning channel, so as to solve the problems of poor spinning efficiency and product quality in existing dry spinning channels.

[0005] To address the aforementioned technical problems, this application provides a multi-segment gradient heating and airflow optimization structure for a dry spinning channel, comprising: The system comprises a vertically arranged tunnel body, a flow guiding system disposed on the inner wall of the tunnel body, a flow stabilizing device disposed at the air inlet of the tunnel body, an air collecting hood disposed on the top of the tunnel body, and a spinneret installed below the air collecting hood; the tunnel body is provided with a preheating section, a main volatile section, and a setting section arranged sequentially along the spinning direction; the inner walls of the preheating section, the main volatile section, and the setting section are all equipped with independently controllable heating plates; and the air inlet includes air inlets respectively opened on the lower side of each section of the tunnel body.

[0006] In this design, the main tunnel is divided into three functional sections: a preheating section, a main evaporation section, and a setting section. Each section is equipped with an independently controlled heating plate, enabling precise temperature field control. This allows the solvent to evaporate as needed after the spinning solution is extruded from the spinneret, reducing the solvent residue rate in the spun fibers. Air inlets located on the lower side of each section, along with flow stabilization devices at the inlets, allow for independent adjustment of airflow parameters according to the specific requirements of each section. This rectifies the incoming hot air into a uniform and stable laminar flow, effectively eliminating the disturbance to the filaments caused by eddies and turbulence generated by high-speed airflow in traditional tunnels, significantly reducing the risk of filament vibration and breakage. The inner wall guiding system further optimizes the airflow distribution, allowing the hot air to flow smoothly along the designed path and fully contact the filaments, extending the effective heat and mass transfer time. Simultaneously, the top gas collection hood effectively collects and discharges solvent-containing waste gas, preventing solvent vapor from accumulating in the tunnel and affecting the subsequent evaporation process. Through the synergistic optimization of the temperature and flow fields, the entire system significantly improves production efficiency and reduces energy consumption while ensuring fiber forming quality.

[0007] As a preferred option, the airflow guiding system includes an array of inclined guide vanes, which guides the airflow entering the main body of the tunnel to form a spiral motion path.

[0008] Furthermore, the deflector array is set at a 45° angle.

[0009] In this design, the flow direction of the airflow entering the tunnel is changed by setting up a baffle array. Since the baffle array is inclined relative to the central axis of the tunnel body, the hot air, after entering the tunnel body 1, gains a tangential velocity component while moving axially, thus exhibiting a spiral motion path along the baffle array. Compared with the traditional straight upward airflow, this significantly prolongs the trajectory of the hot air within the tunnel. The spiral airflow generates a uniform surrounding effect on the filaments during its ascent, thereby greatly increasing the effective contact time and contact area between the hot air and the filaments, resulting in more thorough and uniform heat transfer and solvent evaporation. At the same time, the centrifugal force of the spiral airflow helps to quickly remove the evaporated solvent vapor from the filament surface, preventing the formation of a saturated layer of solvent vapor on the filament surface that would hinder the continued evaporation of the internal solvent.

[0010] As a preferred option, the heating plate includes a honeycomb microporous ceramic heating plate with a pore size of 0.5-1 mm.

[0011] As a preferred option, the flow stabilization device includes a porous damping plate disposed inside the air inlet, a sensor assembly installed at the air inlets of the preheating section and the main evaporation section, and a laser vibration meter installed on the inner wall side of the main evaporation section; the sensor assembly includes a piezoelectric ceramic element for sensing air intake parameters.

[0012] Furthermore, the spinneret has a ring structure, and the laser vibration meter is installed at the lower end of the gas collection hood near the inner ring of the spinneret.

[0013] In this design, a porous damping plate inside the air inlet disperses the incoming high-speed airflow into numerous tiny airflow beams, eliminating the formation of large-scale eddies and turbulence, thus transforming the airflow into a stable laminar flow state before it enters the main tunnel body. Simultaneously, a laser vibration meter can monitor the filament vibration state in real time. When the detected filament vibration amplitude exceeds a set threshold, the airflow field distribution can be optimized by adjusting the air intake parameters or heating temperature. This active vibration monitoring and control system solves the problems of filament vibration and breakage caused by high-speed airflow disturbance in traditional tunnels, significantly reducing the breakage rate and fuzz production.

[0014] Furthermore, the sensor assembly includes at least one of a temperature sensor, a pressure sensor, and a flow rate sensor.

[0015] As a preferred option, the upper part of the shaping section is also provided with a gas collection port, which is connected to the solvent gas classification and recovery system.

[0016] Furthermore, the solvent gas staged recovery system includes: a high-pressure flash evaporation recovery device connected to the top opening of the gas collecting hood for recovering high-temperature gas; and a distillation recovery device connected to the gas collecting port for recovering low-temperature gas.

[0017] In this scheme, by graded recovery of solvent gases, not only is the solvent recovery rate improved and raw material costs reduced, but energy waste caused by mixing all waste gases in traditional processes is also avoided.

[0018] As a preferred option, the temperature control range of the preheating section is 180-200℃, the temperature control range of the main volatilization section is 220-240℃, and the temperature control range of the setting section is 190-210℃.

[0019] In this scheme, the preheating section uses a lower temperature to avoid the problem of rapid film formation on the surface, which makes it difficult for the internal solvent to diffuse. The main evaporation section provides the highest temperature to promote rapid solvent evaporation. The setting section is appropriately cooled to prevent the fiber from overheating and degrading. This gradient temperature field design greatly improves the thermal energy utilization efficiency and reduces the solvent residue rate.

[0020] The beneficial effects of this application are as follows: 1. This application's solution divides the main body of the spinning tunnel into three functional sections: a preheating section, a main evaporation section, and a setting section. Each section is equipped with an independently controlled heating plate, achieving precise temperature field control. This allows for controlled solvent evaporation of the spinning solution after extrusion from the spinneret, reducing solvent residue in the spun fibers. The air inlets located on the lower side of each section, along with flow stabilizing devices at the inlets, enable independent adjustment of airflow parameters according to the actual needs of each section. This rectifys the incoming hot air into a uniform and stable laminar flow, effectively eliminating the high temperature issues common in traditional spinning tunnels. The eddies and turbulence generated by the high-speed airflow significantly reduce the risk of filament vibration and breakage. The inner wall guiding system further optimizes the airflow distribution, allowing hot air to flow smoothly along the designed path and fully contact the filament, extending the effective heat and mass transfer time. At the same time, the top gas collection hood effectively collects and discharges waste gas containing solvent, preventing solvent vapor from accumulating in the channel and affecting the subsequent evaporation process. Through the synergistic optimization of the temperature field and flow field, the entire system significantly improves production efficiency and reduces energy consumption while ensuring fiber forming quality.

[0021] 2. The proposed solution alters the airflow direction of the incoming channel by setting up a guide vane array. Since the guide vane array is inclined relative to the central axis of the channel body, the hot air, upon entering the channel body 1, acquires a tangential velocity component while moving axially, thus exhibiting a spiral motion path along the guide vane array. Compared to traditional linear upward airflow, this significantly prolongs the trajectory of the hot air within the channel. The spiral airflow, during its ascent, creates a uniform, surrounding effect on the filaments, greatly increasing the effective contact time and area between the hot air and the filaments, resulting in more thorough and uniform heat transfer and solvent evaporation. Simultaneously, the centrifugal force of the spiral airflow helps to quickly remove the evaporated solvent vapor from the filament surface, preventing the formation of a saturated layer on the filament surface that would hinder further evaporation of the internal solvent.

[0022] 3. This application's solution disperses the incoming high-speed airflow into numerous tiny airflow beams by installing a porous damping plate inside the air inlet, eliminating the formation of large-scale eddies and turbulence, and transforming the airflow into a stable laminar flow state before entering the main body of the tunnel. Simultaneously, a laser vibration meter can monitor the vibration state of the filaments in real time. When the detected filament vibration amplitude exceeds a set threshold, the airflow field distribution can be optimized by adjusting the air intake parameters or heating temperature. This active vibration monitoring and control system solves the problem of filament vibration and breakage caused by high-speed airflow disturbance in traditional tunnels, significantly reducing the breakage rate and fuzz production.

[0023] 4. The proposed solution improves solvent recovery rate and reduces raw material costs by performing staged recovery of solvent gases, and avoids energy waste caused by mixing all waste gases in traditional processes.

[0024] 5. The solution of this application avoids the problem of internal solvent diffusion caused by rapid film formation on the surface by using a lower temperature in the preheating section, provides the highest temperature in the main evaporation section to promote rapid solvent evaporation, and appropriately cools down in the setting section to prevent fiber overheating and degradation. This gradient temperature field design greatly improves the thermal energy utilization efficiency and reduces the solvent residue rate. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a multi-segment gradient heating and airflow optimization structure for a dry spinning channel according to an embodiment of this application; Figure 2 This is a partial cross-sectional schematic diagram of a multi-segment gradient heating and airflow optimization structure for a dry spinning channel according to an embodiment of this application. Figure 3 yes Figure 2 A partial enlarged view of the current stabilizing device.

[0026] Explanation of reference numerals in the attached figures: 1. Main tunnel body; 2. Flow guiding system; 3. Air inlet; 4. Flow stabilizing device; 5. Gas collection hood; 6. Spinneret; 7. Heating plate; 11. Preheating section; 12. Main evaporation section; 13. Shaping section; 31. Porous damping plate; 131. Gas collection port. Detailed Implementation

[0027] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to more clearly illustrate the technical solution of this application, and are therefore merely examples and should not be used to limit the scope of protection of this application. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Spandex spinning solution with a viscosity of 8000-11000P was used, and the spinning solution was delivered to the spinneret inside the tunnel body 1 of the following examples and comparative examples at a speed of 800-1100 m / min for spinning tests.

[0029] Example 1 The dry spinning tunnel multi-segment gradient heating and airflow optimization structure of this embodiment includes a vertically arranged tunnel body 1, which is divided into three segments: a preheating segment 11, a main volatile section 12, and a setting segment 13. Each segment has a honeycomb microporous ceramic heating plate 7 with a pore size of 0.5 mm installed on its inner wall. The temperature of the preheating segment 11 is set to 190°C, the temperature of the main volatile section 12 is set to 235°C, and the temperature of the setting segment 13 is set to 195°C.

[0030] Each section has an independent air inlet 3 on its lower side. A porous damping plate 31 with a 2mm aperture and a 10% opening ratio is installed inside the air inlet 3. Temperature sensors, pressure sensors, and flow rate sensors are installed at the air inlets 3 of the preheating section 11 and the main evaporation section 12. A 45° inclined guide plate array 2 is installed on the inner wall of the main tunnel body 1, with a spacing of 50mm between the guide plates, guiding the airflow in a spiral upward path. A laser vibration meter (not shown in the figure) is installed on the inner wall side of the main evaporation section 12 to monitor the filament vibration in real time. If the detected vibration exceeds ±8mm, the airflow velocity is reduced by 2-5%.

[0031] The main body of the tunnel 1 is a cylindrical structure with a total length of 10m. The preheating section 11 is 2m long, the main evaporation section 12 is 6m long, and the setting section 13 is 2m long. A conical gas collection hood 5 is installed at the top, and an annular spinneret 6 is installed below the gas collection hood 5. A high-pressure flash evaporation recovery device is connected to the top of the gas collection hood 5, and a distillation recovery device is connected to the gas collection port on the upper side of the setting section 13, forming a solvent gas staged recovery system.

[0032] Example 2 The difference between the multi-segment gradient heating and airflow optimization structure of the dry spinning tunnel in this embodiment and that in Embodiment 1 is: Each section of the main tunnel 1 has a honeycomb microporous ceramic heating plate 7 with a hole diameter of 1mm installed on its inner wall. The temperature of the preheating section 11 is set to 200℃, the temperature of the main volatilization section 12 is set to 240℃, and the temperature of the shaping section 13 is set to 205℃. The inner wall of the main tunnel 1 is provided with a 45° inclined guide plate array 2, with a guide plate spacing of 100mm, guiding the airflow in a spiral upward path. A laser vibration meter is installed at the lower end of the gas collection hood 5 near the inner ring of the spinneret 6, and the rest is the same as in Embodiment 1.

[0033] Example 3 The difference between the multi-segment gradient heating and airflow optimization structure of the dry spinning tunnel in this embodiment and that in embodiment 1 is that only one air inlet 3 is provided at the bottom of the tunnel body 1, and no independent air inlet 3 is provided on the lower side of each segment. The rest is the same as in embodiment 1.

[0034] Example 4 The difference between the multi-segment gradient heating and airflow optimization structure of the dry spinning tunnel in this embodiment and that in embodiment 1 is that the guide plate array 2 is not set inside the tunnel body 1, and the airflow rises vertically. The rest is the same as in embodiment 1.

[0035] Example 5 The difference between the multi-segment gradient heating and airflow optimization structure of the dry spinning tunnel in this embodiment and that in embodiment 1 is that the flow stabilizing device 4 is not installed at the independent air inlet 3 on the lower side of each segment; otherwise, it is the same as in embodiment 1.

[0036] Example 6 The difference between the multi-segment gradient heating and airflow optimization structure of the dry spinning tunnel in this embodiment and that in embodiment 1 is that: no solvent classification and recovery system is configured, and only the top gas collection hood 5 is used for unified recovery, while the rest is the same as in embodiment 1.

[0037] Comparative Example 1 The dry spinning tunnel adopts a cuboid structure with a total length of 10m. The inner wall is equipped with a single-temperature-controlled electric heating plate, with the temperature set at 240℃ throughout. A single air inlet is located at the bottom, without a flow stabilization device; hot air enters directly into the tunnel body and rises vertically. There is no exhaust hood at the top; exhaust vents are only located on the upper side wall of the tunnel, and there is no solvent recovery system.

[0038] The spinning solution was monitored during the process in the spinning tunnels of each embodiment and comparative example. The energy consumption required to produce one kilogram of spandex fiber product and the solvent recovery rate of the spinning tunnels used in the embodiments and comparative examples of this application were measured. The prepared spandex fiber products were tested according to FZ / T 50006-2013 "Test Method for Tensile Properties of Spandex Filament" and GB / 41671-2022 "Determination of Solvent Residue in Chemical Fibers". The fiber solvent residue was detected by gas chromatography-mass spectrometry to determine the content of DMAC (N,N-dimethylacetamide) and DMF (N,N-dimethylformamide) in the fiber. The measurement results are expressed in ppm (1 mg / kg = 1 ppm). The results are detailed in Table 1.

[0039] Table 1. Comparison data of the effects of spinning solution on the tunnel implementation of each example and comparative example. Based on the experimental data shown in Table 1, a comparative analysis of the proposed multi-segment gradient heating and airflow optimization structure for dry spinning tunnels, the traditional tunnel structure, and the partially optimized embodiment of the structure in this application leads to the following conclusions: Examples 1 and 2 employed the complete technical solution of this application. Compared with Comparative Example 1, they exhibited significant advantages in terms of fiber solvent residue, unit fiber energy consumption, solvent recovery rate, and fiber breaking strength and elongation at break. This verifies that the multi-segment gradient heating and airflow optimization structure of the dry spinning channel proposed in this application can effectively improve spinning efficiency, reduce energy consumption, and improve fiber quality.

[0040] Comparing Example 1 and Example 3, Example 3 showed inferior fiber solvent residue, energy consumption, and solvent recovery rate compared to Example 1. This indicates that the segmented design of the main tunnel (preheating section, main evaporation section, and setting section) and the configuration of independently controlled heating plates and independent air inlets for each section can effectively optimize the solvent evaporation process.

[0041] Comparing Example 1 and Example 4, Example 4 showed inferior fiber solvent residue, energy consumption, and breaking strength compared to Example 1. This demonstrates that the inclined baffle array effectively prolongs the contact time and contact area between the hot air and the filaments, promoting the full and uniform evaporation of the solvent.

[0042] Comparing Example 1 and Example 5, Example 5 not only showed a significant increase in fiber solvent residue and a marked decrease in breaking strength, but also exhibited the problem of "filament not forming". This indicates that the flow stabilizing device installed at the air inlet is an important factor in ensuring the stability of the spinning process, reducing the breakage rate, and improving fiber quality.

[0043] Comparing Example 1 and Example 6, the solvent recovery rate in Example 6 decreased to 56.7%, far lower than the 86% in Example 1. This indicates that the solvent fractionation recovery system can effectively improve the solvent recovery efficiency.

[0044] Experimental results show that the dry spinning channel employing multi-segment gradient heating and optimized airflow structure, under the synergistic effect of optimized temperature and flow fields, not only improves spinning efficiency and product quality but also significantly reduces energy consumption and solvent residue. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-segment gradient heating and airflow optimization structure for a dry spinning channel, characterized in that, include: The tunnel body (1) is vertically arranged, the flow guiding system (2) is arranged on the inner wall of the tunnel body (1), the flow stabilizing device (4) is arranged on the air inlet (3) of the tunnel body (1), the gas collecting hood (5) is arranged on the top of the tunnel body, and the spinneret (6) is installed below the gas collecting hood (5); the tunnel body (1) is arranged in sequence along the spinning direction with a preheating section (11), a main volatile section (12) and a setting section (13), and the inner walls of the preheating section (11), the main volatile section (12) and the setting section (13) are all equipped with independently controllable heating plates (7), and the air inlet (3) includes air inlets (3) respectively opened on the lower side of each section of the tunnel body (1); The flow guiding system (2) includes an array of inclined flow guide plates, which is used to guide the airflow entering the main body of the channel (1) to form a spiral motion path; The flow stabilizing device (4) includes a porous damping plate (31) disposed inside the air inlet (3), a sensor assembly installed at the air inlet (3) of the preheating section (11) and the main evaporation section (12), and a laser vibration meter installed on the inner wall side of the main evaporation section (12); the sensor assembly includes a piezoelectric ceramic element for sensing the air intake parameters.

2. The structure as described in claim 1, characterized in that, The deflector array is set at a 45° angle.

3. The structure as described in claim 1, characterized in that, The heating plate (7) includes a honeycomb microporous ceramic heating plate with a pore size of 0.5-1mm.

4. The structure as described in claim 1, characterized in that, The spinneret (6) has a ring structure, and the laser vibration meter is installed at the lower end of the gas collection hood (5) near the inner ring of the spinneret (6).

5. The structure as described in claim 1, characterized in that, The sensor assembly includes at least one of a temperature sensor, a pressure sensor, and a flow rate sensor.

6. The structure as described in claim 1, characterized in that, The upper part of the shaping section (13) is also provided with a gas collection port (131), which is connected to the solvent gas graded recovery system.

7. The structure as described in claim 6, characterized in that, The solvent gas staged recovery system includes: A high-pressure flash evaporation recovery device connected to the top opening of the gas collection hood (5) is used to recover high-temperature gas; and a distillation recovery device connected to the gas collection port (131) is used to recover low-temperature gas.

8. The structure as described in claim 1, characterized in that, The temperature control range of the preheating section (11) is 180-200℃, the temperature control range of the main volatile section (12) is 220-240℃, and the temperature control range of the shaping section (13) is 190-210℃.

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