Multi-section gradient heating and airflow optimizing structure of dry spinning channel

Abstract

The invention discloses a multi-section gradient heating and airflow optimizing structure of a dry spinning channel. Comprising a vertically-arranged channel body, a flow guide system arranged on the inner wall of the channel body, a flow stabilizing device arranged at an air inlet of the channel body, an air collecting hood arranged at the top of the channel body and a spinning nozzle installed below the air collecting hood. The channel main body is sequentially provided with a preheating section, a main volatilization section and a shaping section along the spinning direction, the inner walls of the preheating section, the main volatilization section and the shaping section are respectively provided with a heating plate which can be independently controlled, and the air inlets comprise air inlets which are respectively formed in the lower side parts of all sections of the channel main body. The multi-section gradient heating and airflow optimizing structure of the dry spinning channel can effectively solve the problem that an existing dry spinning channel is poor in spinning efficiency and product quality.

Description

Technical Field

[0001] The present application relates to the technical field of spandex dry spinning equipment, and in particular to a multi-stage gradient heating and airflow optimization structure of a dry spinning tunnel. Background Art

[0002] Dry spinning is a mature and widely used fiber-forming technology, playing a key role in the preparation of a variety of high-performance polymer materials, including polyacrylonitrile, cellulose acetate, and polyurethane elastic fibers. Its core process involves extruding the spinning solution through the spinneret, where hot air evaporates the solvent within the spinning shaft, 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 mostly adopt a straight-cylinder or simple structural design. This structure results in a generally short effective contact time between the hot air and the nascent filaments. Due to insufficient contact time, even at higher temperatures, it is difficult for the solvent to fully evaporate, resulting in a generally high solvent residual rate in the spun fiber. In order to improve spinning efficiency and product quality, existing technologies have been improved by increasing the air flow velocity in the tunnel or increasing the hot air temperature. However, traditional tunnel designs are difficult to effectively control the disturbance of high-speed airflow on fine filaments, and are prone to generating unstable airflow in local areas, causing the high-speed moving filaments to shake violently. This filament shaking not only increases the generation of lint on the fiber surface, but also easily causes fatigue fracture of the filaments under high-frequency vibration, which significantly increases the breakage rate of the production line. Increasing the hot air temperature results in a lot of energy waste and significantly increases production costs. Summary of the Invention

[0004] The technical problem to be solved by the present application is to provide a multi-stage gradient heating and airflow optimization structure for a dry spinning tunnel to solve the problems of poor spinning efficiency and product quality in the existing dry spinning tunnel.

[0005] In order to solve the above technical problems, the present application provides a multi-stage gradient heating and airflow optimization structure of a dry spinning tunnel, comprising: A vertically arranged corridor body, a flow guide system arranged on the inner wall of the corridor body, a flow stabilizing device arranged at the air inlet of the corridor body, an air collecting hood arranged on the top of the corridor body and a spinneret installed below the air collecting hood; the corridor body is provided with a preheating section, a main volatilization section and a shaping section in sequence along the spinning direction, the inner walls of the preheating section, the main volatilization section and the shaping section are all installed with independently controllable heating plates, and the air inlet includes air inlets respectively opened on the lower side of each section of the corridor body.

[0006] In this scheme, by dividing the main body of the tunnel into three functional sections: preheating section, main volatilization section and shaping section, and arranging independently controlled heating plates in each section, precise control of the temperature field is achieved, so that the solvent volatilization of the spinning solution can be controlled according to actual needs after it is extruded from the spinneret, thereby reducing the solvent residual rate of the spun fiber; the air inlets arranged on the lower side of each section, together with the flow stabilization device at the air inlet, can independently adjust the airflow parameters according to the actual needs of each section, and rectify the incoming hot air into a uniform and stable laminar flow, effectively eliminating the disturbance of the filaments caused by eddy currents and turbulence generated by high-speed airflow in traditional tunnels, and significantly reducing the risk of filament shaking and breakage; the inner wall guide system further optimizes the airflow distribution, so that the hot air can flow smoothly along the designed path and fully contact the filaments, extending the effective heat and mass transfer time. At the same time, the top gas collection hood effectively collects and discharges the exhaust gas containing solvent, preventing the accumulation of solvent vapor in the tunnel and affecting the subsequent volatilization process. Through the coordinated optimization of temperature field and flow field, the entire system significantly improves production efficiency and reduces energy consumption while ensuring the quality of fiber forming.

[0007] As a preferred option, the guide system includes an array of guide plates arranged obliquely, and the guide plate array is used to guide the airflow entering the channel body to form a spiral motion path.

[0008] Furthermore, the guide plate array is arranged at an inclination of 45°.

[0009] In this solution, the direction of the airflow entering the tunnel is changed by setting up an array of guide plates. Since the guide plate array is tilted relative to the central axis of the tunnel body, after the hot air enters the tunnel body 1, it acquires a tangential velocity component while moving axially, thereby forming a spiral motion path along the guide plate array. Compared with traditional straight rising airflow, the hot air's motion trajectory in the tunnel is significantly extended. During the rising process, the spiral airflow will produce a uniform surrounding coating effect on the filaments, thereby greatly increasing the effective contact time and contact area between the hot air and the filaments, making heat transfer and solvent volatilization more complete and uniform. At the same time, the centrifugal force of the spiral airflow helps to quickly remove the volatilized solvent vapor from the surface of the filaments, preventing the solvent vapor from forming a saturated layer on the surface of the filaments and hindering the continued volatilization of the internal solvent.

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

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

[0012] Furthermore, the spinneret is an annular structure, and the laser vibrometer is installed at the lower end of the gas collecting hood near the inner ring of the spinneret.

[0013] In this solution, a porous damping plate is installed inside the air inlet to disperse the incoming high-speed airflow into countless fine streams, eliminating the formation of large-scale eddies and turbulence, and transforming the airflow into a stable laminar state before entering the main channel. At the same time, a laser vibrometer can monitor the vibration state of the wire strips in real time. When the vibration amplitude of the wire strips exceeds a set threshold, the air flow 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 wire strip jitter and breakage caused by high-speed airflow disturbances in traditional channels, significantly reducing the breakage rate and the occurrence of lint.

[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, a gas collecting port is further provided on the upper side of the shaping section, and the gas collecting port is connected to a solvent gas graded recovery system.

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

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

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

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

[0020] The beneficial effects of this application are: 1. The present application scheme realizes precise control of the temperature field by dividing the main body of the tunnel into three functional sections: preheating section, main volatilization section and shaping section, and arranging independently controlled heating plates in each section, so that the solvent volatilization of the spinning solution can be controlled according to actual needs after it is extruded from the spinneret, thereby reducing the solvent residual rate of the spun fiber; the air inlets respectively arranged on the lower side of each section cooperate with the flow stabilizing device at the air inlet, which can independently adjust the airflow parameters according to the actual needs of each section, rectify the incoming hot air into a uniform and stable laminar flow, and effectively eliminate the high temperature in the traditional tunnel. The eddies and turbulence generated by the high-speed airflow disturb the filaments, significantly reducing the risk of filament shaking and breakage; the inner wall guide 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. At the same time, the top gas collection hood effectively collects and discharges waste gas containing solvents, preventing solvent vapor from accumulating in the tunnel and affecting the subsequent volatilization process. Through the coordinated optimization of temperature field and flow field, the entire system significantly improves production efficiency and reduces energy consumption while ensuring the quality of fiber formation.

[0021] 2. The present application scheme changes the flow direction of the airflow entering the tunnel by setting up a guide plate array. Since the guide plate array is tilted relative to the central axis of the tunnel body, after the hot air enters the tunnel body 1, it obtains a tangential velocity component while moving axially, thereby forming a spiral motion path along the guide plate array. Compared with the traditional straight rising airflow, the movement trajectory of the hot air in the tunnel is significantly extended. The spiral airflow will produce a uniform surrounding coating effect on the filaments during the rising process, thereby greatly increasing the effective contact time and contact area between the hot air and the filaments, making the heat transfer and solvent volatilization more sufficient and uniform; at the same time, the centrifugal force of the spiral airflow helps to quickly remove the volatilized solvent vapor from the surface of the filaments, preventing the solvent vapor from forming a saturated layer on the surface of the filaments and hindering the continued volatilization of the internal solvent.

[0022] 3. This application solution disperses the incoming high-speed airflow into countless tiny streams 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 state before entering the main body of the tunnel. At the same time, the laser vibrometer can monitor the vibration state of the silk strips in real time. When the vibration amplitude of the silk strips exceeds the set threshold, the air flow field distribution can be optimized by adjusting the air intake parameters or heating temperature. The active vibration monitoring and control system solves the problem of silk strip jitter and breakage caused by high-speed airflow disturbances in traditional tunnels, significantly reducing the breakage rate and the generation of hair.

[0023] 4. This application solution not only improves the solvent recovery rate and reduces the raw material cost by recovering the solvent gas in a graded manner, but also avoids the energy waste caused by mixing all the waste gases in the traditional process.

[0024] 5. The present application scheme adopts a lower temperature in the preheating section to avoid the problem of rapid film formation on the surface that makes it difficult for the internal solvent to diffuse, provides the highest temperature in the main volatilization section to promote rapid volatilization of the solvent, and appropriately cools down the shaping section to prevent overheating and degradation of the fiber. This gradient temperature field design greatly improves the thermal energy utilization efficiency and reduces the solvent residual rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a multi-stage gradient heating and airflow optimization structure of a dry spinning tunnel in an embodiment of the present application; Figure 2 This is a partial structural cross-sectional diagram of a multi-stage gradient heating and airflow optimization structure of a dry spinning tunnel in an embodiment of the present application; Figure 3 yes Figure 2 A partial enlarged view of the flow stabilization device.

[0026] Description of reference numerals: 1. Corridor body; 2. Flow guide system; 3. Air inlet; 4. Flow stabilization device; 5. Gas collecting hood; 6. Spinneret; 7. Heating plate; 11. Preheating section; 12. Main volatilization section; 13. Shaping section; 31. Porous damping plate; 131. Gas collecting port. DETAILED DESCRIPTION

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

[0028] Spandex spinning stock solution with a viscosity of 8000-11000P was used and transported to the spinneret in the tunnel body 1 of the following embodiments and comparative examples at a speed of 800-1100 m / min to perform a spinning test.

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

[0030] Each section has an independent air inlet 3 on the lower side, with a porous damping plate 31 with a 2mm aperture and a 10% porosity installed inside. The air inlets 3 of the preheating section 11 and the main volatilization section 12 are equipped with temperature sensors, pressure sensors, and flow rate sensors. An array of guide plates 2 with a 45° inclination and a spacing of 50mm are installed on the inner wall of the main channel 1, guiding the airflow in a spiral upward path. A laser vibrometer (not shown) is installed on the side of the inner wall of the main volatilization section 12 to monitor the vibration of the wire in real time. If the vibration exceeds the ±8mm range, 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 10 meters. The preheating section (11) is 2 meters long, the primary volatilization section (12) is 6 meters long, and the shaping section (13) is 2 meters long. A conical gas collection hood (5) is located at the top, beneath which is mounted an annular spinneret (6). The top of the hood (5) is connected to a high-pressure flash recovery unit, while the gas collection port on the upper side of the shaping section (13) is connected to a distillation recovery unit, forming a staged solvent gas recovery system.

[0032] Example 2 The multi-stage gradient heating and airflow optimization structure of the dry spinning tunnel of this embodiment differs from that of Example 1 in that: The inner wall of each section of the tunnel body 1 is installed with a honeycomb microporous ceramic heating plate 7 with a pore size of 1mm. 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 tunnel body 1 is provided with a 45° inclined guide plate array 2 with a spacing of 100 mm to guide the airflow in a spiral ascending path. A laser vibrometer is installed at the lower end of the gas collecting cover 5 near the inner ring of the spinneret 6. The rest is the same as in Example 1.

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

[0034] Example 4 The multi-stage gradient heating and airflow optimization structure of the dry spinning tunnel of this embodiment differs from that of Example 1 in that: no guide plate array 2 is provided inside the tunnel body 1, the airflow rises vertically, and the rest is the same as that of Example 1.

[0035] Example 5 The multi-section gradient heating and airflow optimization structure of the dry spinning tunnel of this embodiment differs from that of Example 1 in that the independent air inlet 3 provided at the lower side of each section is not equipped with a flow stabilizing device 4 , and the rest is the same as that of Example 1.

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

[0037] Comparative Example 1 The dry spinning tunnel, a rectangular parallelepiped structure with a total length of 10 meters, is equipped with a single temperature-controlled electric heating plate on the inner wall, set at 240°C throughout the entire process. A single air inlet is located at the bottom, without a flow stabilization device. Hot air enters the tunnel body directly and rises vertically. There is no exhaust hood at the top; only exhaust ports are located on the upper sidewalls of the tunnel. There is no solvent recovery system.

[0038] The spinning solution was monitored as it passed through the spindles of each of the Examples and Comparative Examples. The energy consumption per kilogram of spandex fiber product produced and the solvent recovery rate of the spinning spindles used in the Examples and Comparative Examples were measured. The resulting spandex fiber products were tested according to FZ / T 50006-2013, "Test Method for Tensile Properties of Spandex Yarn," and GB / 41671-2022, "Determination of Residual Solvents in Chemical Fibers." Residual solvent in the fibers was determined by gas chromatography-mass spectrometry to measure the content of DMAC (N,N-dimethylacetamide) and DMF (N,N-dimethylformamide). The results are expressed in ppm (1 mg / kg = 1 ppm). The results are shown in Table 1.

[0039] Table 1 Comparative data of the effects of spinning solution passing through the channels of each embodiment and comparative example Based on the experimental data shown in Table 1, a comparative analysis of the multi-stage gradient heating and airflow optimization structure of the dry spinning tunnel proposed in this application with the traditional tunnel structure and the embodiment of the partial structural optimization of this application yields the following conclusions: Examples 1 and 2, which employed the complete technical solution of this application, demonstrated significant advantages over Comparative Example 1 in terms of residual fiber solvent, energy consumption per unit fiber, solvent recovery rate, and fiber breaking strength and elongation. This demonstrates that the multi-stage gradient heating and airflow optimization structure of the dry spinning tunnel proposed in this application can effectively improve spinning efficiency, reduce energy consumption, and improve fiber quality.

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

[0041] Comparing Example 1 with Example 4, the fiber solvent residue, energy consumption, and breaking strength of Example 4 were all inferior to those of Example 1. This proves that the inclined guide plate array can effectively prolong the contact time and contact area between the hot air and the filaments, promoting full and uniform volatilization of the solvent.

[0042] Comparing Example 1 with Example 5, not only did Example 5 have significantly higher residual solvent in the fiber and significantly lower breaking strength, but it also exhibited the problem of "fiber not forming." This indicates that the flow stabilization device at the air inlet is an important factor in ensuring a stable spinning process, reducing the breakage rate, and improving fiber quality.

[0043] Comparing Example 1 with Example 6, the solvent recovery rate of Example 6 dropped to 56.7%, which is much lower than 86% of Example 1. This shows that the solvent graded recovery system can effectively improve the solvent recovery efficiency.

[0044] Experimental results show that the dry spinning tunnel with multi-stage gradient heating and airflow optimization structure not only improves the spinning efficiency and product quality, but also significantly reduces energy consumption and solvent residual rate under the synergistic effect of optimizing the temperature field and flow field. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-stage gradient heating and airflow optimization structure for a dry spinning tunnel, characterized in that: include: A vertically arranged channel body (1), a flow guide system (2) arranged on the inner wall of the channel body (1), a flow stabilizing device (4) arranged at the air inlet (3) of the channel body (1), an air collecting hood (5) arranged on the top of the channel body, and a spinneret (6) installed below the air collecting hood (5); the channel body (1) is provided with a preheating section (11), a main volatilization section (12) and a shaping section (13) in sequence along the spinning direction, the inner walls of the preheating section (11), the main volatilization section (12) and the shaping section (13) are all provided with independently controllable heating plates (7), and the air inlet (3) includes air inlets (3) respectively opened at the lower side of each section of the channel body (1).

2. The structure according to claim 1, characterized in that The flow guide system (2) comprises an array of guide plates arranged obliquely, and the array of guide plates is used to guide the airflow entering the tunnel body (1) to form a spiral motion path.

3. The structure according to claim 2, characterized in that The guide plate array is arranged at an inclination of 45 degrees.

4. The structure according to claim 1, wherein The heating plate (7) comprises a honeycomb microporous ceramic heating plate, and the pore diameter of the honeycomb microporous ceramic heating plate is 0.5-1 mm.

5. The structure according to claim 1, wherein: The flow stabilizing device (4) comprises a porous damping plate (31) arranged inside the air inlet (3), a sensor assembly installed at the air inlet (3) of the preheating section (11) and the main volatilization section (12), and a laser vibrometer installed on the side of the inner wall of the main volatilization section (12); the sensor assembly comprises a piezoelectric ceramic element for sensing intake parameters.

6. The structure according to claim 5, characterized in that The spinneret (6) is an annular structure, and the laser vibrometer is installed at a position at the lower end of the gas collecting hood (5) close to the inner ring of the spinneret (6).

7. The structure according to claim 5, characterized in that The sensor assembly includes at least one of a temperature sensor, a pressure sensor, and a flow rate sensor.

8. The structure according to claim 1, wherein The upper side of the shaping section (13) is also provided with a gas collecting port (131), and the gas collecting port (131) is connected to the solvent gas classification recovery system.

9. The structure according to claim 8, characterized in that The solvent gas classification recovery system comprises: A high-pressure flash recovery device connected to the top opening of the gas collecting hood (5) is used to recover high-temperature gas; and a distillation recovery device connected to the gas collecting port (131) is used to recover low-temperature gas.

10. The structure according to claim 1, wherein The temperature control range of the preheating section (11) is 180-200°C, the temperature control range of the main volatilization section (12) is 220-240°C, and the temperature control range of the shaping section (13) is 190-210°C.

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