Device and method for improving spinnability of polyamide chips

Abstract

The present invention relates to a device and method for improving the spinnability of polyamide chips, comprising a feeding device, a suspension configuration tank, a powder suction machine, a centrifuge, a grinder, a fine phase suspension collection tank, a coarse phase sedimentation device, and a fine phase suspension two-stage circulation filtration device. Feeding is performed through the feeding device, a titanium dioxide suspension of a certain concentration is configured in the suspension configuration tank and then centrifuged. The fine particle solution enters the fine phase suspension two-stage circulation filtration device for filtration for use in the production line, and the fine particle solution enters the coarse phase sedimentation device. After grinding and sedimentation, it returns to the suspension configuration tank to participate in the preparation of the solution. The present invention can reduce the waste rate of caprolactam (CPL) aqueous solution and titanium dioxide and increase the filtration amount of the fine phase titanium dioxide suspension on the 1un filter screen, thereby improving the spinnability of the matte polyamide 6 chips. At the same time, the present invention achieves a breakthrough from scratch in the development of matte ultrafine denier products with a monofilament ≤0.5dpf, filling the blank field of nylon 6 ultrafine denier fibers.

Description

Technical Field

[0001] The invention relates to the technical field of polyamide production, in particular to a device and a method for improving the spinnability of polyamide chips. Background Art

[0002] As consumer spending rises, market demand continues to rise. Conventional nylon products are no longer able to meet the demands of the high-end market. Ultrafine denier products with a monofilament size of ≤0.5 dpf are gaining increasing popularity and recognition, particularly matte ultrafine denier fibers. Titanium dioxide is widely used as a matting agent in the nylon weaving industry to reduce excessive optical reflectivity on the surface of nylon fibers, reduce transparency, and increase whiteness. Commercially available titanium dioxide powder is tetragonal anatase titanium dioxide, containing approximately 3% silicon-containing impurities. If not filtered, these silicon-containing impurities will affect the spinnability of polyamide 6 chips. Furthermore, the Ti-O bonds in titanium dioxide are highly polar. In aqueous solutions, they cause surface-adsorbed water molecules to dissociate due to polarization, generating hydroxyl groups. These surface hydroxyl groups enhance the adsorption of titanium dioxide, leading to aggregation in suspension, forming larger aggregates. Through extensive experimental verification, the inventors have found that a higher proportion of titanium dioxide particles less than 1 μm in the suspension improves uniformity and stability, and consequently, improves the spinning conditions and fiber properties of ultrafine denier nylon 6 fibers. Therefore, addressing titanium dioxide agglomeration and reducing the amount of coarse titanium dioxide particles are key to producing ultrafine denier nylon 6 products.

[0003] Currently, nylon companies mainly use two methods to solve the above problems: the first method is to regularly discharge and repeatedly clean the sediment at the bottom of the titanium dioxide storage tank or add self-circulating stirring. This method requires a lot of labor for cleaning, and the waste rate of caprolactam (CPL) aqueous solution and titanium dioxide is high. In addition, self-circulating stirring cannot separate the agglomerates out of the system, so it still cannot solve the technical barriers to the production of ultra-fine denier products. The second method is to add titanium dioxide to the preparation tank of the caprolactam aqueous solution during the preparation of matte nylon chips, stir and mix evenly into a slurry, send it to the separator for separation, filter the coarse-particle titanium dioxide into the coarse phase tank, and then regularly discharge and treat the coarse phase tank. This method results in a high waste rate of caprolactam (CPL) aqueous solution and titanium dioxide. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for improving the spinnability of polyamide chips, which can effectively re-grind the coarse-phase titanium dioxide suspension, reduce the waste rate of alkali-low caprolactam (CPL) aqueous solution and titanium dioxide, and improve the influence of the alkali-low coarse-phase titanium dioxide suspension on downstream spinning, thereby improving the proportion, uniformity and stability of the fine-phase titanium dioxide suspension, and helping to achieve stable production and mass production of ultrafine denier products.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a device for improving the spinnability of polyamide chips, characterized in that it includes a feeding device, a suspension configuration tank, a powder suction machine, a centrifuge, a grinder, a fine phase suspension collection tank, a coarse phase sedimentation device, and a fine phase suspension two-stage circulation filtration device, a first pipeline is provided at the inlet of the suspension configuration tank, a first pneumatic valve is provided on the first pipeline, the outlet of the feeding device is connected to the first pipeline, the outlet of the suspension configuration tank is connected to the inlet of the powder suction machine via a second pipeline, the outlet of the powder suction machine is connected to the inlet of the suspension configuration tank via a third pipeline, the outlet of the powder suction machine is connected to the inlet of the centrifuge via a fourth pipeline, and the fourth pipeline is provided with a The second pneumatic valve is connected between the third pipeline and the fourth pipeline, the first outlet of the centrifuge is connected with the inlet of the fine phase suspension collecting tank via the fifth pipeline, the outlet of the fine phase suspension collecting tank is connected with the inlet of the fine phase suspension two-stage circulation filtration device via the sixth pipeline, the second outlet of the centrifuge is connected with the inlet of the coarse phase sedimentation device via the seventh pipeline, the outlet of the coarse phase sedimentation device is connected with the inlet of the grinder via the eighth pipeline, the outlet of the grinder is connected with the inlet of the suspension configuration tank via the ninth pipeline, the outlet of the fine phase suspension two-stage circulation filtration device is connected with a user unit via the tenth pipeline, and the third pneumatic valve and the first flowmeter are provided on the tenth pipeline.

[0006] Furthermore, the two-stage circulating filtration device for the fine phase suspension includes a suspension buffer tank, a daily tank, a circulating material transfer pump, a primary filter, a discharge pump, and a secondary filter. The outlet of the fine phase suspension collecting tank is connected to the inlet of the suspension buffer tank via the sixth pipeline, the outlet of the suspension buffer tank is connected to the inlet of the circulating material transfer pump via the eleventh pipeline, the outlet of the circulating material transfer pump is connected to the inlet of the primary filter via the twelfth pipeline, the outlet of the primary filter is connected to the inlet of the suspension buffer tank via the thirteenth pipeline, and the outlet of the primary filter is connected to the inlet of the suspension buffer tank via the fourteenth pipeline. The thirteenth pipeline is connected with the inlet of the daily tank, the thirteenth pipeline is connected with the fourteenth pipeline, a fourth pneumatic valve is provided at the connection between the thirteenth pipeline and the fourteenth pipeline, the outlet of the daily tank is connected with the inlet of the discharge pump via the fifteenth pipeline, the outlet of the discharge pump is connected with the inlet of the secondary filter via the sixteenth pipeline, the outlet of the secondary filter is connected with the inlet of the daily tank via the seventeenth pipeline, the outlet of the secondary filter is connected with the user unit via the tenth pipeline, and the fifteenth pipeline is connected with the tenth pipeline.

[0007] Furthermore, a first pressure transmitter is provided at the inlet of the first-level filter, a second pressure transmitter is provided at the outlet of the first-level filter, a third pressure transmitter is provided at the inlet of the second-level filter, and a fourth pressure transmitter is provided at the outlet of the second-level filter.

[0008] Furthermore, it also includes multiple levels of filters that are consistent with the primary filter and the secondary filter. The filters are connected in series with the two-stage circulation filtration device for the fine phase suspension to improve the filtration performance.

[0009] Furthermore, a liquid level gauge is provided at the outer lower end of the suspension buffer tank.

[0010] Furthermore, the coarse phase sedimentation device includes a coarse phase suspension collecting tank, a sedimentation mechanism, and a coarse phase suspension delivery pump. The sedimentation mechanism includes a first sedimentation tank and a second sedimentation tank. The second outlet of the centrifuge is connected to the inlet of the coarse phase suspension collecting tank via the seventh pipeline, the outlet of the coarse phase suspension collecting tank is connected to the inlet of the first sedimentation tank via the eighteenth pipeline, the outlet of the coarse phase suspension collecting tank is connected to the inlet of the second sedimentation tank via the nineteenth pipeline, the eighteenth pipeline and the nineteenth pipeline are connected, the outlet of the first sedimentation tank is connected to the inlet of the coarse phase suspension delivery pump via the twentieth pipeline, the outlet of the second sedimentation tank is connected to the inlet of the coarse phase suspension delivery pump via the twenty-first pipeline, the twentieth pipeline and the twenty-first pipeline are connected, and the outlet of the coarse phase suspension delivery pump is connected to the inlet of the grinder via the eighth pipeline.

[0011] Furthermore, the feeding device includes a caprolactam feeding pipe, a pure water feeding pipe, a titanium dioxide feeding pipe, a caprolactam aqueous solution preparation tank, and a caprolactam aqueous solution pump. The caprolactam feeding pipe is connected to the first inlet of the caprolactam aqueous solution preparation tank, and a second flow meter and a fifth pneumatic valve are provided on the caprolactam water feeding pipe. The pure water feeding pipe is connected to the second inlet of the caprolactam aqueous solution preparation tank, and a third flow meter and a sixth pneumatic valve are provided on the pure water feeding pipe. The outlet of the caprolactam aqueous solution preparation tank is connected to the second inlet of the caprolactam aqueous solution preparation tank through the twenty-second pipe. The twenty-fourth pipeline is provided with a fourth flow meter and a seventh pneumatic valve, the titanium dioxide feed pipe is connected to the first pipeline, the titanium dioxide feed pipe is provided with a fifth flow meter and an eighth pneumatic valve, and the titanium dioxide feed pipe is connected to the twenty-fourth pipeline.

[0012] Furthermore, a fifth pressure transmitter is provided at the outlet of the coarse phase suspension delivery pump.

[0013] Furthermore, an observation hole and a cleaning hole are provided on the top of the sedimentation mechanism, reinforcing ribs are provided on the inner side and bottom of the sedimentation mechanism, the bottom of the sedimentation mechanism is provided with a slope of 3% downward from the horizontal plane, and a discharge valve is provided at the bottom of the side of the sedimentation mechanism.

[0014] A method for improving the spinnability of polyamide chips, characterized in that it is a method using the above-mentioned device for improving the spinnability of polyamide chips, comprising:

[0015] (1) In a suspension preparation tank, the powder suction machine is driven by a motor to rotate at high speed to absorb titanium dioxide powder into the caprolactam aqueous solution, and the titanium dioxide absorbed into the caprolactam aqueous solution is dispersed to form a uniform titanium dioxide suspension;

[0016] (2) transporting the uniform titanium dioxide suspension obtained in step (1) to a centrifuge for separation to obtain a fine phase suspension with fine particles in the upper layer and a coarse phase suspension with coarse particles in the lower layer;

[0017] (3) The fine wire suspension obtained in step (2) is transported to a two-stage circulation filtration device for fine wire suspension and fine phase suspension controlled by a PLC program, wherein the PLC program sets the circulation filtration time, the direction of the air valve, the liquid level limit, and the start and stop of material transportation;

[0018] When the fine-line suspension fine-phase suspension two-stage circulation filtration device receives the fine-line suspension, the liquid level in the device rises to the limit value, and the first-stage circulation filtration begins. When the circulation time is reached, the air valve is turned to start the second-stage circulation filtration. After the fine-phase titanium dioxide suspension with a titanium dioxide particle size of ≤1um is obtained through the two-stage filter with a filter screen of ≤1um, the obtained fine-phase titanium dioxide suspension with a titanium dioxide particle size of ≤1um is transported to the user unit;

[0019] (4) transporting the coarse phase suspension of coarse particles obtained in step (2) to a coarse phase settling device capable of settling and deslagging to obtain an upper suspension and impurities in a lower layer;

[0020] (5) The upper suspension obtained in step (4) is sent to a grinder for grinding and then sent to a suspension preparation tank to continue to participate in the preparation of the titanium dioxide solution, and the lower impurities are discharged to the impurity treatment system for treatment.

[0021] The beneficial effects of the present invention are as follows: the present invention adds a two-stage circulating filtration device for a titanium dioxide fine phase suspension to the titanium dioxide suspension configuration system, and the circulating filtration by the two-stage filter reduces the labor intensity of the cleaning operation, reduces the waste rate of the caprolactam (CPL) aqueous solution and titanium dioxide, and improves the proportion, uniformity and stability of titanium dioxide with a particle size of less than 1um in the titanium dioxide suspension added to the production line, thereby achieving stable and mass production of ultrafine denier products; a coarse phase sedimentation device is added to the titanium dioxide suspension configuration system, and the separated coarse phase suspension is placed in the first sedimentation tank or the second sedimentation tank, and the sedimentation is sufficient according to the process requirements. For a long time, the non-titanium dioxide impurities in the titanium dioxide suspension are deposited at the bottom. After the sedimentation is completed, the upper suspension is sent to the grinder through the coarse phase suspension delivery pump, and then returned to the configuration system for recycling after grinding. The impurities at the bottom of the first sedimentation tank or the second sedimentation tank are regularly discharged or manually cleaned. This not only reduces the labor intensity of the cleaning operation, but also reduces the waste rate of caprolactam (CPL) aqueous solution and titanium dioxide. Moreover, after the non-titanium dioxide impurities are discharged from the system by sedimentation, it is helpful to increase the proportion, uniformity and stability of titanium dioxide with a particle size of less than 1um in the fine phase titanium dioxide suspension, and help to achieve stable production and mass production of ultrafine denier products. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the process of the present invention;

[0023] Figure 2 A schematic diagram of a flow chart of an embodiment of the present invention;

[0024] Figure 3 It is a front cross-sectional view of the sedimentation tank of the present invention;

[0025] Figure 4 It is a top cross-sectional view of the sedimentation tank of the present invention.

[0026] Figures 1 to 2 The arrows are only for better understanding of the relationship between the devices and the flow direction of the solution.

[0027] Among them: 1. Suspension preparation tank, 2. Powder suction machine, 3. Centrifuge, 4. Fine phase suspension collection tank, 5. Suspension buffer tank, 6. Circulation transfer pump, 7. Primary filter, 8. Daily tank, 9. Discharge pump, 10. Secondary filter, 11. Coarse phase suspension collection tank, 12. First sedimentation tank, 13. Second sedimentation tank, 14. Coarse phase suspension delivery pump, 15. Grinding machine, 16. User unit, 17. First pipeline, 18. First pneumatic valve, 19. Second pipeline, 20. Third pipeline, 21. Fourth pipeline, 22. Second pneumatic valve, 23. Fifth pipeline, 24. Sixth pipeline, 25. Seventh pipeline, 26. Eighth pipeline, 27. Ninth pipeline, 28. Tenth pipeline, 29. Third pneumatic valve, 30. Eleventh pipeline, 31. Twelfth pipeline, 32. Thirteenth pipeline, 33. Fourteenth pipeline, 34. Fourth pneumatic valve, 35. Fifteenth pipeline, 36. Sixteenth pipeline, 37. Seventeenth pipeline, 38. Liquid level gauge, 39. Eighteenth pipeline, 40. Nineteenth pipeline, 41. Twentieth pipeline, 42. Twenty-first pipeline, 43. First pressure transmitter, 44. Second pressure transmitter, 45. Third pressure transmitter, 46. Fourth pressure transmitter, 47. Fifth pressure transmitter, 48. Drain valve, 49. Observation hole, 50. Cleaning hole, 51. Reinforcing rib, 52. First flowmeter, 53. Caprolactam feed pipe, 54. Caprolactam aqueous solution preparation tank, 55. Second flowmeter, 56. Fifth pneumatic valve, 57. Pure water feed pipe, 58. Third flowmeter, 59. Sixth pneumatic valve, 60. Twenty-second pipeline, 61. Caprolactam aqueous solution pump, 62. Twenty-third pipeline, 63. Twenty-fourth pipeline, 64. Seventh pneumatic valve, 65. Fourth flowmeter, 66. Titanium dioxide feed pipe, 67. Eighth pneumatic valve, 68. Fifth flowmeter. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] See also Figure 1The present invention provides an embodiment: a device for improving the spinnability of polyamide chips, characterized in that it includes a feeding device, a suspension preparation tank 1, a powder suction machine 2, a centrifuge 3, a grinder 15, a fine phase suspension collection tank 4, a coarse phase sedimentation device, and a fine phase suspension two-stage circulation filtration device, the inlet of the suspension preparation tank 1 is provided with a first pipe 17, the first pipe 17 is provided with a first pneumatic valve 18, the inlet of the feeding device is connected to the first pipe 17, the outlet of the suspension preparation tank 1 is connected to the inlet of the powder suction machine 2 via a second pipe 19, the outlet of the powder suction machine 2 is connected to the inlet of the suspension preparation tank 1 via a third pipe 20, the outlet of the powder suction machine 2 is connected to the inlet of the centrifuge 3 via a fourth pipe 21, and the fourth pipe 21 is connected to the inlet of the centrifuge 3. A second pneumatic valve 22 is provided on it, the third pipe 20 and the fourth pipe 21 are connected, the first outlet of the centrifuge 3 is connected with the inlet of the fine phase suspension collecting tank 4 through the fifth pipe 23, the outlet of the fine phase suspension collecting tank 4 is connected with the inlet of the fine phase suspension two-stage circulation filtration device through the sixth pipe 24, the second outlet of the centrifuge 3 is connected with the inlet of the coarse phase sedimentation device through the seventh pipe 25, the outlet of the coarse phase sedimentation device is connected with the inlet of the grinder 15 through the eighth pipe 26, the outlet of the grinder 15 is connected with the inlet of the suspension configuration tank 1 through the ninth pipe 27, the outlet of the fine phase suspension two-stage circulation filtration device is connected with the user unit 16 through the tenth pipe 28, and the tenth pipe 28 is provided with a third pneumatic valve 29 and a first flowmeter 52. By closing the first pneumatic valve 18 and the second pneumatic valve 22, a circulation process is formed between the suspension preparation tank 1 and the powder suction machine 2 using the caprolactam aqueous solution. Then, the first pneumatic valve 18 is opened to absorb the bagged titanium dioxide powder into the caprolactam aqueous solution, and the titanium dioxide absorbed into the caprolactam aqueous solution is dispersed, and the alkali-poor agglomerates form a suspension with a relatively uniform particle size distribution. Then, the second pneumatic valve 22 is opened to pass the suspension with a relatively uniform particle size distribution through the centrifuge 3. Centrifugal separation is carried out by utilizing the different gravity between coarse particles and fine particles in the titanium dioxide suspension, wherein the fine particles go from the first outlet at a position relatively above the centrifuge 3 to the fine phase suspension collecting tank 4. After the fine phase suspension from the centrifuge 3 is collected in the fine phase suspension collecting tank 4, the caprolactam aqueous solution is added through the feeding device to adjust the concentration of the titanium dioxide suspension to the concentration required for production, and then enter the fine phase suspension floating circulation filtration device to filter the titanium dioxide suspension, and provide the production line with a suspension of qualified concentration through the switch of the third pneumatic valve 29; the coarse particles enter the coarse phase sedimentation device from the second outlet at a position relatively below the centrifuge 3, and the coarse phase suspension from the coarse phase suspension collecting tank 11 is ground and then enters the suspension preparation tank 1 for recycling.The powder suction machine 2 is a disperser, and the model of the powder suction machine 2 can be C75.000S / ConTi-TDS-5, but is not limited thereto; the model of the centrifuge 3 can be V630 BK III, but is not limited thereto; the model of the grinder 15 can be RNMD200, but is not limited thereto.

[0030] Please continue reading Figure 1As shown, in one embodiment of the present invention, the two-stage circulating filtration device for fine phase suspension includes a suspension buffer tank 5, a daily tank 8, a circulating material transfer pump 6, a primary filter 7, a discharge pump 9, and a secondary filter 10. The outlet of the fine phase suspension collecting tank 4 is connected to the inlet of the suspension buffer tank 5 via the sixth pipeline 24, the outlet of the suspension buffer tank 5 is connected to the inlet of the circulating material transfer pump 6 via the eleventh pipeline 30, the outlet of the circulating material transfer pump 6 is connected to the inlet of the primary filter 7 via the twelfth pipeline 31, and the outlet of the primary filter 7 is connected to the inlet of the primary filter 7 via the thirteenth pipeline 32. It is connected with the inlet of the suspension buffer tank 5, the outlet of the primary filter 7 is connected with the inlet of the daily tank 8 via the fourteenth pipe 33, the thirteenth pipe 32 is connected with the fourteenth pipe 33, and a fourth pneumatic valve 34 is provided at the connection between the thirteenth pipe 32 and the fourteenth pipe 33. The outlet of the daily tank 8 is connected with the inlet of the discharge pump 9 via the fifteenth pipe 35, and the outlet of the discharge pump 9 is connected with the inlet of the secondary filter 10 via the sixteenth pipe 36. The outlet of the secondary filter 10 is connected with the inlet of the daily tank 8 via the seventeenth pipe 37. The outlet of the secondary filter 10 is connected with the user unit 16 via the tenth pipe 28, and the fifteenth pipe 35 is connected with the tenth pipe 28. The fourth pneumatic valve 34 is a pneumatic three-way plug valve. In the PLC control program, an internal circulation time is set for the circulating material transfer pump 6 (often set according to production needs). When the internal circulation time is reached, the circulating material transfer pump 6 will give a signal to the fourth pneumatic valve 34. After receiving the signal, the fourth pneumatic valve 34 will automatically switch to the direction of the first-level filter 7 to the daily tank 8, and start transferring the suspension to the daily tank 8. The filter element accuracy of the first-level filter 7 and the second-level filter 10 can be 1um but is not limited to this. The start and stop of the circulating material transfer pump 6 and the direction change of the fourth pneumatic valve 34 are all automatically completed under the program control of the PLC, without manual operation. Among them, after the suspension buffer tank 5 collects the suspension with qualified concentration from the fine phase suspension collection tank 4, it switches to the direction of the primary filter 7 to the suspension buffer tank 5 through the fourth pneumatic valve, so that the suspension in the suspension buffer tank 5 enters the material transfer circulation pump 6, and then the suspension is transported to the primary filter 7 through the material transfer circulation pump 6. After the suspension comes out of the primary filter 7, it returns to the suspension buffer tank 5 to filter out the agglomerates in the suspension. When the circulation time is reached or the daily tank 8 needs it, the suspension in the suspension buffer tank 5 is transferred to the daily tank 8 through the pump for use in the production line. The daily tank 8 stores the titanium dioxide suspension with qualified concentration and after primary filtration, and performs continuous secondary filtration. In continuous polymerization production, the discharge pump 9 is needed as a power source to continuously and stably provide titanium dioxide suspension to the user unit 16. Please continue to refer to Figure 1 As shown, in one embodiment of the present invention, a first pressure transmitter 43 is provided at the inlet of the primary filter 7, a second pressure transmitter 44 is provided at the outlet of the primary filter 7, a third pressure transmitter 45 is provided at the inlet of the secondary filter 10, and a fourth pressure transmitter 46 is provided at the outlet of the secondary filter 10. A first pressure transmitter 43 is provided at the inlet of the primary filter 7. During the process of transferring the suspension to the daily tank 8, when the pressure reading of the first pressure transmitter 43 drops by 30% compared with the normal pressure reading (or a minimum pressure is set in the PLC), it indicates that the material in the suspension buffer tank 5 has been emptied. The first pressure transmitter 43 will send a signal to the circulating material transfer pump 6, and the circulating material transfer pump 6 will automatically stop after receiving the signal. A second pressure transmitter 44 is provided at the outlet of the primary filter 7, a third pressure transmitter 45 is provided at the inlet of the secondary filter 10, and a fourth pressure transmitter 46 is provided at the outlet. Then, by comparing the pressures at the inlet and outlet of the two filters, the pressure difference ΔP1 of the primary filter 7 and the pressure difference ΔP2 of the secondary filter 10 are set in the program, and the pressure differences ΔP1 and ΔP2 are given. An upper limit alarm value is set so that when the pressure difference ΔP1 or ΔP2 alarm occurs, it means that the filter element in the filter is blocked by debris. The operator can simply replace the filter element with a new one without the need for real-time inspection and monitoring, which saves manpower.

[0031] Please continue reading Figure 2 As shown, in one embodiment of the present invention, multiple filters are also included that are consistent with the primary filter 7 and the secondary filter 10. The filters are connected in series with the two-stage fine-phase suspension circulation filtration device to facilitate improved filtration performance. Filter elements with the same or different filtration accuracies can be installed according to process requirements. Multiple stages of filtration can also be connected in series after the secondary filter 10 to remove agglomerates from the suspension buffer tank 5 and the daily tank 8, increase the filtration rate of the fine-phase titanium dioxide suspension on the 1um filter screen, and thus improve filtration performance.

[0032] Please continue reading Figure 1 As shown, in one embodiment of the present invention, a liquid level gauge 38 is provided at the lower end of the exterior of the suspension buffer tank 5. When the suspension level in the suspension buffer tank 5 rises and reaches the position of the liquid level gauge 38, the liquid level gauge 38 sends a signal to the circulating material transfer pump 6 and the fourth pneumatic valve 34. Upon receiving the signal, the circulating material transfer pump 6 automatically opens, and upon receiving the signal, the fourth pneumatic valve 34 automatically switches to the direction of the primary filter 7 toward the suspension buffer tank 5, starting the internal circulation to remove agglomerates.

[0033] Please continue reading Figure 1As shown, in one embodiment of the present invention, the coarse phase sedimentation device includes a coarse phase suspension collecting tank 11, a sedimentation tank mechanism, and a coarse phase suspension delivery pump 14. The sedimentation tank mechanism includes a first sedimentation tank 12 and a second sedimentation tank 13. The second outlet of the centrifuge 3 is connected to the inlet of the coarse phase suspension collecting tank 11 through the seventh pipeline 25. The outlet of the coarse phase suspension collecting tank 11 is connected to the inlet of the first sedimentation tank 12 through the eighteenth pipeline 39. The coarse phase suspension collecting tank 11 The outlet of the first sedimentation tank 12 is connected to the inlet of the coarse phase suspension delivery pump 14 through the twentieth pipeline 41, the outlet of the second sedimentation tank 13 is connected to the inlet of the coarse phase suspension delivery pump 14 through the twenty-first pipeline 42, the twentieth pipeline 41 is connected to the twenty-first pipeline 42, and the outlet of the coarse phase suspension delivery pump 14 is connected to the inlet of the grinder 15 through the eighth pipeline 26. The separated coarse phase suspension collected in the coarse phase suspension collection tank 11 is placed in the first sedimentation tank 12 or the second sedimentation tank 13 (one is in use and the other is standby, and the two can be switched at any time and used alternately). According to the process requirements, the sedimentation time is long enough (such as 8 hours) to deposit the non-titanium dioxide impurities in the titanium dioxide suspension at the bottom. After the sedimentation is completed, the upper suspension is sent to the grinder 15 through the coarse phase suspension delivery pump 14, and after grinding, it is returned to the configuration system for recycling. This reduces the waste rate of caprolactam (CPL) aqueous solution and titanium dioxide, and the sedimentation method helps to increase the proportion, uniformity and stability of titanium dioxide with a particle size of less than 1um in the fine phase titanium dioxide suspension, which helps to achieve stable production and mass production of ultrafine denier products.

[0034] Please continue reading Figure 1As shown, in one embodiment of the present invention, the feeding device includes a caprolactam feeding pipe 53, a pure water feeding pipe 57, a titanium dioxide feeding pipe 66, a caprolactam aqueous solution preparation tank 54, and a caprolactam aqueous solution pump 61. The caprolactam feeding pipe 53 is connected to the first inlet of the caprolactam aqueous solution preparation tank 54, and a second flow meter 55 and a fifth pneumatic valve 56 are provided on the caprolactam water feeding pipe. The pure water feeding pipe 57 is connected to the second inlet of the caprolactam aqueous solution preparation tank 54, and a third flow meter 58 and a sixth pneumatic valve 59 are provided on the pure water feeding pipe 57. The outlet of the caprolactam aqueous solution preparation tank 54 is connected to the inlet of the caprolactam aqueous solution pump 61 via a twenty-second pipeline 60, and the outlet of the caprolactam aqueous solution pump 61 is connected to the third inlet of the caprolactam aqueous solution preparation tank 54 via a twenty-third pipeline 62. The caprolactam aqueous solution pump 61 The outlet is connected to the first pipeline 17 via the twenty-fourth pipeline 63, and the twenty-fourth pipeline is provided with a fourth flowmeter 65 and a seventh pneumatic valve 64. The titanium dioxide feed pipe 66 is connected to the first pipeline 17, and the titanium dioxide feed pipe 66 is provided with a fifth flowmeter 68 and an eighth pneumatic valve 67. The titanium dioxide feed pipe 66 is connected to the twenty-fourth pipeline 63. In this way, according to the concentration and dosage of the caprolactam aqueous solution required by the process, a certain amount of caprolactam can be added to the caprolactam aqueous solution preparation tank 54 through the second flowmeter 55 on the caprolactam feed pipe 53, and a certain amount of pure water can be added to the caprolactam aqueous solution preparation tank 54 through the third flowmeter 58 on the pure water feed pipe 57; the caprolactam aqueous solution pump 61 is turned on for circulation to evenly mix the caprolactam and pure water in the caprolactam aqueous solution preparation tank 54 to obtain a caprolactam aqueous solution of the concentration required by the process. During the preparation of the titanium dioxide suspension, the caprolactam aqueous solution of the concentration required by the process is transported to the suspension preparation tank 1 through the first pipeline 17 through the fourth flowmeter 65 according to the preparation amount requirement. During the replenishment process of adjusting the concentration of the titanium dioxide suspension, titanium dioxide is transported to the suspension preparation tank 1 through the first pipeline 17 through the fourth flowmeter 65 on the titanium dioxide feed pipe 66 to adjust the concentration to the concentration required by the process.

[0035] Please continue reading Figure 1 As shown, in one embodiment of the present invention, a fifth pressure transmitter 47 is provided at the outlet of the coarse phase suspension delivery pump 14. When the pressure reading of the fifth pressure transmitter 47 drops by 30% below the normal pressure reading (or a minimum pressure is set in the PLC), indicating that the material in the sedimentation tank has been emptied, the fifth pressure transmitter 47 will send a signal to the coarse phase suspension delivery pump 14, and the coarse phase suspension delivery pump 14 will automatically stop upon receiving the signal, eliminating the need for real-time inspection and monitoring, and reducing manpower consumption.

[0036] Please continue reading Figures 3 and 4 As shown, in one embodiment of the present invention, the top of the settling mechanism is provided with an observation hole 49 and a cleaning hole 50. The inner side and bottom of the settling mechanism are both provided with reinforcing ribs 51. The bottom of the settling mechanism is provided with a slope of 3% downward from the horizontal plane. A discharge valve 48 is provided at the bottom of the side of the settling mechanism. The settling mechanism has two settling tanks, namely the first settling tank 12 and the second settling tank 13. The cleaning hole 50 and the observation hole 49 are provided on the top of the settling tank to observe the liquid level and clean the interior of the settling tank. Reinforcing ribs 51 are designed on the sides and bottom of the settling tank to prevent the liquid from squeezing the side walls and causing deformation of the settling tank. The discharge valve 48 is provided at the low point of the side of the settling tank to discharge the sediment that can be discharged before cleaning the interior of the settling tank. This allows impurities at the bottom of the first settling tank 12 or the second settling tank 13 to be discharged regularly or manually cleaned (the discharge or cleaning cycle is determined according to process requirements, generally once a month, rather than daily discharge and cleaning), which can reduce the labor intensity of the cleaning operation.

[0037] See also Figure 1 The present invention provides another embodiment: a method for improving the spinnability of polyamide chips, characterized in that the method uses the above-mentioned device for improving the spinnability of polyamide chips, comprising:

[0038] (1) In the suspension preparation tank 1, the powder suction machine 2 is driven by a motor to rotate at high speed to suck the titanium dioxide powder into the caprolactam aqueous solution, and the titanium dioxide sucked into the caprolactam aqueous solution is dispersed to form a uniform titanium dioxide suspension;

[0039] (2) transporting the uniform titanium dioxide suspension obtained in step (1) to a centrifuge 3 for separation to obtain a fine phase suspension with fine particles in the upper layer and a coarse phase suspension with coarse particles in the lower layer;

[0040] (3) The fine wire suspension obtained in step (2) is transported to a two-stage circulation filtration device for fine wire suspension and fine phase suspension controlled by a PLC program, wherein the PLC program sets the circulation filtration time, the direction of the air valve, the liquid level limit, and the start and stop of material transportation;

[0041] When the fine-line suspension fine-phase suspension two-stage circulation filtration device receives the fine-line suspension, the liquid level in the device rises to the limit value, and the first-stage circulation filtration begins. When the circulation time is reached, the air valve is rotated to start the second-stage circulation filtration. After the fine-phase titanium dioxide suspension with a titanium dioxide particle size of ≤1um is obtained after circulation filtration through the two-stage filter with a filter screen of ≤1um, the obtained fine-phase titanium dioxide suspension with a titanium dioxide particle size of ≤1um is transported to the user unit;

[0042] (4) transporting the coarse phase suspension of coarse particles obtained in step (2) to a coarse phase settling device capable of settling and deslagging to obtain an upper suspension and impurities in a lower layer;

[0043] (5) The upper suspension obtained in step (4) is sent to a grinder for grinding and then sent to the suspension preparation tank 1 to continue to participate in the preparation of the titanium dioxide solution, and the lower impurities are discharged to the impurity treatment system for treatment.

[0044] After the feeding device is used to feed the material, a certain concentration of titanium dioxide suspension is prepared in the suspension preparation tank 1 and then centrifuged. The fine particle solution enters the fine phase suspension two-stage circulation filtration device for filtration to be used for the production line. The fine particle solution enters the coarse phase sedimentation device, and after grinding and sedimentation, it returns to the suspension preparation tank 1 to participate in the preparation of the solution. The fine phase suspension two-stage circulation filtration device includes a suspension buffer tank 5, a daily tank 8, a circulation transfer pump 6, a primary filter 7, a discharge pump 9 and a secondary filter 10. The program sets the time for the liquid level in the suspension buffer tank 5 to rise to the maximum limit of the suspension buffer tank and the circulation filtration time (the circulation time is set according to production needs). When the liquid level reaches the liquid limit, the pneumatic three-way stopcock automatically switches to the first-level filter and rotates in the direction of the suspension buffer tank after receiving the signal, starting the first-level circulation filtration. When the circulation time arrives, the pneumatic three-way stopcock automatically switches to the air valve after receiving the signal to continue rotating the first-level filter in the direction of the daily tank, starting the second-level circulation filtration. The pressure reading can also be monitored in the PLC control program. When the pressure reading is higher than normal or a pressure limit is set to monitor the pressure situation in the filter, when the pressure reading drops by 30% or is lower than the pressure limit, a prompt signal is sent to determine whether the filter is blocked and to prompt the staff to replace the filter element in time; the coarse phase sedimentation device includes a coarse phase suspension collecting tank 11, two sedimentation tanks and a coarse phase suspension delivery pump 14, which sends the collected coarse particle solution to the sedimentation tank for impurity sedimentation for a certain period of time, wherein the two sedimentation tanks can be used alternately. The method can reduce the waste rate of caprolactam (CPL) aqueous solution and titanium dioxide, help improve the spinnability of polyamide chips, and achieve mass production of ultra-fine denier products.

[0045] The present invention has the following working principle: a titanium dioxide suspension configured in a suspension preparation tank and a powder suction machine is separated into coarse and fine particles by a centrifuge; after the fine phase suspension is collected in a fine phase suspension collecting tank, it is transported to a fine phase suspension circulation device; the fine line suspension is circulated and filtered through a suspension buffer tank, a daily tank, a circulating material transfer pump, a primary filter, a discharge pump, a secondary filter and other devices, and then transported to a user unit; the coarse particle solution flows to a coarse phase sedimentation device, and the solution is collected through a coarse phase suspension collecting tank; the first sedimentation tank and the second sedimentation tank are used alternately to let the solution stand and discharge slag, and then the remaining solution is transported to a grinder to grind or grind the coarse particles or agglomerates in the suspension above the sedimentation tank and transport them back to the suspension preparation tank for repeated reuse, thereby saving raw materials.

[0046] The spinnability of matte polyamide 6 chips prepared before and after the use of this invention was analyzed, and the number of drifting yarns and broken ends per 1,000 spindles for POY SD 20D / 24F, 20D / 68F, 48D / 34F, and 70D / 48F nylon 6 filament products was calculated (Table 1). The data in Table 1 demonstrates that the use of this invention effectively improves the spinnability of the chips, with both drifting yarns and broken ends per 1,000 spindles reduced by an average of 0.1 and 4.9, respectively. Furthermore, this invention achieves a breakthrough in producing matte ultrafine denier products with a monofilament thickness of ≤0.5 dpf (e.g., FD 20D / 68F), filling the gap in the field of ultrafine denier nylon 6 fibers.

[0047] Table 1 Spinnability of matt polyamide 6 chips prepared before and after the present invention

[0048]

[0049] The operation of the device and the implementation of the method in the present invention are controlled by a PLC control program. The PLC control program mentioned in the present invention is a prior art and is clearly understood by those skilled in the art, so it will not be described in detail here.

[0050] The above description is only a preferred embodiment of the present invention and should not be understood as limiting the present application. All equivalent changes and modifications made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A device for improving the spinnability of polyamide chips, characterized in that: The invention comprises a feeding device, a suspension configuration tank, a powder sucking machine, a centrifuge, a grinder, a fine phase suspension collecting tank, a coarse phase sedimentation device, and a fine phase suspension two-stage circulation filtration device. A first pipeline is provided at the inlet of the suspension configuration tank, a first pneumatic valve is provided on the first pipeline, the outlet of the feeding device is connected to the first pipeline, the outlet of the suspension configuration tank is connected to the inlet of the powder sucking machine via a second pipeline, the outlet of the powder sucking machine is connected to the inlet of the suspension configuration tank via a third pipeline, the outlet of the powder sucking machine is connected to the inlet of the centrifuge via a fourth pipeline, a second pneumatic valve is provided on the fourth pipeline, and a valve is provided between the third pipeline and the fourth pipeline. The centrifuge is connected to the inlet of the fine phase suspension collecting tank via a fifth pipe, the outlet of the fine phase suspension collecting tank is connected to the inlet of the fine phase suspension two-stage circulation filtering device via a sixth pipe, the second outlet of the centrifuge is connected to the inlet of the coarse phase sedimentation device via a seventh pipe, the outlet of the coarse phase sedimentation device is connected to the inlet of the grinder via an eighth pipe, the outlet of the grinder is connected to the inlet of the suspension configuration tank via a ninth pipe, the outlet of the fine phase suspension two-stage circulation filtering device is connected to a user unit via a tenth pipe, and the tenth pipe is provided with a third pneumatic valve and a first flow meter; The two-stage circulating filtration device for fine phase suspension includes a suspension buffer tank, a daily tank, a circulating material transfer pump, a primary filter, a discharge pump, and a secondary filter. The outlet of the fine phase suspension collecting tank is connected to the inlet of the suspension buffer tank via the sixth pipeline, the outlet of the suspension buffer tank is connected to the inlet of the circulating material transfer pump via the eleventh pipeline, the outlet of the circulating material transfer pump is connected to the inlet of the primary filter via the twelfth pipeline, the outlet of the primary filter is connected to the inlet of the suspension buffer tank via the thirteenth pipeline, and the outlet of the primary filter is connected to the inlet of the suspension buffer tank via the fourteenth pipeline. The inlet of the daily tank is connected, the thirteenth pipeline is connected to the fourteenth pipeline, and a fourth pneumatic valve is provided at the connection between the thirteenth pipeline and the fourteenth pipeline. The outlet of the daily tank is connected to the inlet of the discharge pump via the fifteenth pipeline, and the outlet of the discharge pump is connected to the inlet of the secondary filter via the sixteenth pipeline. The outlet of the secondary filter is connected to the inlet of the daily tank via the seventeenth pipeline. The outlet of the secondary filter is connected to the user unit via the tenth pipeline, and the fifteenth pipeline is connected to the tenth pipeline. The coarse phase sedimentation device includes a coarse phase suspension collecting tank, a sedimentation mechanism, and a coarse phase suspension delivery pump. The sedimentation mechanism includes a first sedimentation tank and a second sedimentation tank. The second outlet of the centrifuge is connected to the inlet of the coarse phase suspension collecting tank via the seventh pipeline, the outlet of the coarse phase suspension collecting tank is connected to the inlet of the first sedimentation tank via the eighteenth pipeline, the outlet of the coarse phase suspension collecting tank is connected to the inlet of the second sedimentation tank via the nineteenth pipeline, the eighteenth pipeline is connected to the nineteenth pipeline, the outlet of the first sedimentation tank is connected to the inlet of the coarse phase suspension delivery pump via the twentieth pipeline, the outlet of the second sedimentation tank is connected to the inlet of the coarse phase suspension delivery pump via the twenty-first pipeline, the twentieth pipeline is connected to the twenty-first pipeline, and the outlet of the coarse phase suspension delivery pump is connected to the inlet of the grinder via the eighth pipeline; The feeding device includes a caprolactam feeding pipe, a pure water feeding pipe, a titanium dioxide feeding pipe, a caprolactam aqueous solution preparation tank, and a caprolactam aqueous solution pump. The caprolactam feeding pipe is connected to the first inlet of the caprolactam aqueous solution preparation tank, and a second flow meter and a fifth pneumatic valve are provided on the caprolactam feeding pipe. The pure water feeding pipe is connected to the second inlet of the caprolactam aqueous solution preparation tank, and a third flow meter and a sixth pneumatic valve are provided on the pure water feeding pipe. The outlet of the caprolactam aqueous solution preparation tank is connected to the second inlet of the caprolactam aqueous solution preparation tank through a twenty-second pipeline. The inlet of the caprolactam aqueous solution pump is connected, the outlet of the caprolactam aqueous solution pump is connected with the third inlet of the caprolactam aqueous solution preparation tank via the twenty-third pipeline, the outlet of the caprolactam aqueous solution pump is connected with the first pipeline via the twenty-fourth pipeline, the twenty-fourth pipeline is provided with a fourth flow meter and a seventh pneumatic valve, the titanium dioxide feed pipe is connected with the first pipeline, the titanium dioxide feed pipe is provided with a fifth flow meter and an eighth pneumatic valve, and the titanium dioxide feed pipe is connected with the twenty-fourth pipeline.

2. The device for improving the spinnability of polyamide chips according to claim 1, wherein: A first pressure transmitter is provided at the inlet of the primary filter, a second pressure transmitter is provided at the outlet of the primary filter, a third pressure transmitter is provided at the inlet of the secondary filter, and a fourth pressure transmitter is provided at the outlet of the secondary filter.

3. The device for improving the spinnability of polyamide chips according to claim 1, wherein: It also includes multiple levels of filters that are consistent with the primary filter and the secondary filter. The filters are connected in series with the two-stage circulation filtration device for fine phase suspension to improve the filtration performance.

4. The device for improving the spinnability of polyamide chips according to claim 3, characterized in that: A liquid level gauge is provided at the outer lower end of the suspension buffer tank.

5. The device for improving the spinnability of polyamide chips according to claim 1, characterized in that: A fifth pressure transmitter is provided at the outlet of the coarse phase suspension delivery pump.

6. The device for improving the spinnability of polyamide chips according to claim 1, wherein: An observation hole and a cleaning hole are provided on the top of the sedimentation mechanism, reinforcing ribs are provided on the inner side and bottom of the sedimentation mechanism, a slope of 3% downward from the horizontal plane is provided on the bottom of the side of the sedimentation mechanism, and a discharge valve is provided at the bottom of the side of the sedimentation mechanism.

7. A method for improving the spinnability of polyamide chips, characterized in that: The method of using the device for improving the spinnability of polyamide chips according to claim 1 comprises: (1) In the suspension preparation tank, the powder suction machine is driven by the electric drive to rotate at high speed to absorb the titanium dioxide powder into the caprolactam aqueous solution, and the titanium dioxide absorbed into the caprolactam aqueous solution is dispersed to form a uniform titanium dioxide suspension with a concentration of 15-30%; (2) transporting the uniform titanium dioxide suspension obtained in step (1) to a centrifuge for separation to obtain a fine phase suspension with fine particles in the upper layer and a coarse phase suspension with coarse particles in the lower layer; (3) The fine phase suspension obtained in step (2) is transported to a two-stage circulation filtration device for fine phase suspension controlled by a PLC program, and the PLC program sets the circulation filtration time, the direction of the pneumatic valve, the liquid level limit, and the start and stop of material transportation; When the fine phase suspension two-stage circulation filtration device receives the fine phase suspension, the liquid level in the device rises to the limit value, and the first-stage circulation filtration begins. When the circulation time is reached, the pneumatic valve rotates and the second-stage circulation filtration begins. After the fine phase titanium dioxide suspension with a titanium dioxide particle size of ≤1um is obtained through the two-stage filter with a filter screen of ≤1um, the fine phase titanium dioxide suspension with a titanium dioxide particle size of ≤1um is transported to the user unit. (4) transporting the coarse phase suspension of coarse particles obtained in step (2) to a coarse phase settling device capable of settling and deslagging to obtain an upper suspension and impurities in a lower layer; (5) The upper suspension obtained in step (4) is sent to a grinder for grinding and then sent to a suspension preparation tank to continue to participate in the preparation of titanium dioxide solution, and the lower impurities are discharged to the impurity treatment system for treatment.

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