Double-final polycondensation reaction kettle device capable of simultaneously producing high-viscosity polyester melt and low-viscosity polyester melt

Abstract

The invention belongs to the technical field of polyester production equipment, and particularly relates to a double-final polycondensation reaction kettle device capable of simultaneously producing high-viscosity and low-viscosity polyester melts.The double-final polycondensation reaction kettle device comprises a first esterification reaction kettle, a second esterification reaction kettle, a first pre-polycondensation reaction kettle, a second pre-polycondensation reaction kettle, a high-viscosity final polycondensation reaction kettle and a low-viscosity final polycondensation reaction kettle which are communicated in sequence; the discharge end of the high-viscosity final polycondensation reaction kettle is respectively connected to the spinning unit and the slice production unit through a first melt conveying pipeline; and the discharge end of the low-viscosity final polycondensation reaction kettle is connected to the spinning unit and the slice production unit through a second melt conveying pipeline respectively. By arranging the double-final polycondensation reaction kettles with remarkable length difference and the independent vacuum pump assembly, raw material distribution is realized by combining a diverter valve, high-viscosity and low-viscosity melts are simultaneously and stably produced by the same set of device, the product diversity is improved, and an online toner adding assembly is additionally arranged, so that the color value of a final product is uniform, and the production efficiency is improved. And strict requirements of subsequent spinning on chromatic aberration are met.

Description

Technical Field

[0001] This invention relates to the field of polyester production equipment technology, specifically to a dual-final polycondensation reactor capable of simultaneously producing high- and low-viscosity polyester melts. Background Technology

[0002] In polyester melt spinning production, traditional five-reactor units typically consist of two identical pre-polymerization reactors and a final polymerization reactor. Because the reactors are of uniform specifications, melt viscosity can only be controlled by a single process parameter, making it impossible to simultaneously meet the production needs of both high-viscosity and low-viscosity melts. Switching product viscosities requires significant adjustments to the equipment (such as replacing reactor components and adjusting the overall vacuum pump assembly), which is not only time-consuming and labor-intensive but also leads to production interruptions, reduced efficiency, and limited product variety with poor market adaptability.

[0003] Melt viscosity is a core indicator of polyester product quality, directly affecting spinning stability and product performance. Traditional equipment lacks targeted viscosity control structures, leading to viscosity loss in high-viscosity melts during transport due to pipeline resistance and filtration, while low-viscosity melts are prone to viscosity fluctuations due to side reactions caused by excessively high temperatures. Furthermore, the color difference between high and low viscosity melts is difficult to control, further limiting product quality stability. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a dual-final polycondensation reactor device capable of simultaneously producing high- and low-viscosity polyester melts. This device enables the synchronous production of high- and low-viscosity melts using the same equipment, improving product diversity and quality stability, reducing production costs, and solving the problems of the inability to simultaneously and stably produce high- and low-viscosity melts, and the ease with which product quality is affected by the conveying process and color value differences.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0008] A dual-final polycondensation reactor device capable of simultaneously producing high and low viscosity polyester melt includes a first esterification reactor, a second esterification reactor, a first pre-polycondensation reactor, and a second pre-polycondensation reactor connected in sequence. A diversion valve is connected to the outlet of the second pre-polycondensation reactor, and the diversion valve is connected to a high viscosity final polycondensation reactor and a low viscosity final polycondensation reactor through two branch pipes respectively.

[0009] The high-viscosity final polycondensation reactor is longer than the low-viscosity final polycondensation reactor, and each is equipped with an independent vacuum pump assembly. The high-viscosity final polycondensation reactor is 13342 mm long, and the vacuum degree of the matching vacuum pump assembly is controlled at 100-250 Pa, so that the melt residence time reaches 3 hours to increase the melt viscosity. The low-viscosity final polycondensation reactor is 8025 mm long, and the vacuum degree of the matching vacuum pump assembly is controlled at 300-600 Pa, so that the melt residence time is 1 hour to control the lower viscosity. This length difference makes the final polycondensation residence time of the high-viscosity reactor longer than that of the low-viscosity reactor, thereby meeting the production needs of melts with different viscosities. Under the condition of the same catalyst content, different vacuum degree control combined with the difference in reactor length can accurately control the viscosity of the melt.

[0010] The discharge end of the high-viscosity final polycondensation reactor is connected to the spinning unit and the chip production unit respectively through the first melt conveying pipe. The pipe length is shorter than the second melt conveying pipe, which can reduce the pressure loss and viscosity drop of the high-viscosity melt during the conveying process and ensure that the intrinsic viscosity of the high-viscosity polyester chips is maintained within the range of 0.800±0.010dl / g.

[0011] The discharge end of the low-viscosity final polycondensation reactor is connected to the spinning unit and the chip production unit respectively through the second melt conveying pipe;

[0012] The slicing production unit includes a pelletizer and a melt cooling mechanism for processing the melt into slices;

[0013] The spinning unit includes a spinning box and a melt distribution assembly for directly spinning the melt into polyester filament.

[0014] Furthermore, the high-viscosity final polycondensation reactor is composed of an upper tank and a lower tank that cooperate with each other, and the low-viscosity final polycondensation reactor has the same structure as the high-viscosity final polycondensation reactor.

[0015] Both the upper and lower tanks are integrally equipped with adjustable tank sections. The two adjustable tank sections are nested together and slidably connected, which facilitates the adjustment of the reactor size according to actual needs, better adapts to usage requirements, and improves ease of use. Sealing rings are provided at the overlapping parts of the adjustable tank sections to ensure a stable and sealed connection. At the same time, sealing lips are provided at the sliding joint ends of the adjustable tank sections. The sealing lips abut against the side wall of the corresponding adjustable tank section, and sealing rings are placed at the abutment parts of the sealing lips to form a stable and effective sealed connection.

[0016] Both the upper and lower tanks are equipped with end plates, and plug-in sleeves are evenly distributed on the end plates. The connecting rod is inserted into the plug-in sleeves, and the connecting rod and the plug-in sleeve are fixedly connected by a fixing pin. During the adjustment process, the position of the upper tank is adjusted by sliding on the lower tank to realize the size adjustment operation of the reactor tank. After the adjustment is completed, the connecting rod is inserted into the plug-in sleeves on the two end plates, and then the connecting rod is fixedly connected to the plug-in sleeve with the fixing pin, thus fixing the upper and lower tanks in the adjusted position.

[0017] Furthermore, the melt filter and melt cooler are installed on the first melt conveying pipeline. The filter can remove impurities in the melt, and the melt cooler helps to reduce the melt conveying temperature, while suppressing side reactions, effectively controlling the viscosity drop of the melt, and ensuring that the intrinsic viscosity of the low-viscosity melt is stable at 0.470±0.010 dl / g.

[0018] Furthermore, it also includes an online colorant addition component, the outlet of which is connected to the feed end of the second esterification reactor. Since the high viscosity and low viscosity chips have different process parameters during production, their colors may differ. This online colorant addition component can adjust the color value to ensure that the color difference is minimized during subsequent spinning.

[0019] The online toner addition component includes a toner storage tank and a mixer. The outlet of the mixer is connected to the feed pipe of the second esterification reactor through a feed pipe. A metering pump is installed on the feed pipe. The metering pump can accurately control the amount of toner added. The mixer can fully mix the toner with the melt to ensure the effect of color value adjustment.

[0020] (III) Beneficial Effects

[0021] Compared with the prior art, the present invention provides a dual-final polycondensation reactor apparatus capable of simultaneously producing high and low viscosity polyester melts, which has the following beneficial effects:

[0022] This invention overcomes the limitation of traditional equipment where "a single reactor can only produce a single viscosity" by setting up a double final polycondensation reactor with significant length differences and an independent vacuum pump assembly, combined with a flow divider valve to achieve raw material distribution. It enables the simultaneous and stable production of high-viscosity and low-viscosity melts in the same unit, improving product diversity. In addition, an online colorant addition assembly is added, which uses a metering pump to precisely control the amount of colorant added, solving the natural color value difference between high and low viscosity melts, so that the color value of the final product is uniform and meets the strict requirements for color difference in subsequent spinning processes. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the low-viscosity final polycondensation reactor in this invention;

[0025] Figure 3 This is a schematic diagram of the online toner adding component in this invention;

[0026] Figure 4 This is a schematic diagram of the high-viscosity final polycondensation reactor in this invention;

[0027] Figure 5 This is a cross-sectional view of the tank body of the high-viscosity final polycondensation reactor in this invention.

[0028] In the diagram: 1. First esterification reactor; 2. Second esterification reactor; 3. First pre-polymerization reactor; 4. Second pre-polymerization reactor; 401. Diverter valve; 402. Branch pipe; 5. High-viscosity final polymerization reactor; 501. Upper tank; 502. Lower tank; 503. End plate; 504. Insert sleeve; 505. Connecting rod; 506. Fixing pin; 507. Adjustment section tank; 508. First melt conveying pipe; 6. Low-viscosity final polymerization reactor; 601. Second melt conveying pipe; 7. Online toner addition assembly; 701. Toner storage tank; 702. Mixer; 703. Metering pump; 704. Conveying pipe; 8. Vacuum pump assembly. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example

[0031] like Figure 1 and Figure 2 As shown, one embodiment of the present invention proposes a dual-final polycondensation reactor device capable of simultaneously producing high and low viscosity polyester melts, comprising a first esterification reactor 1, a second esterification reactor 2, a first pre-polycondensation reactor 3, and a second pre-polycondensation reactor 4 connected in sequence. During production, purified terephthalic acid (PTA) and ethylene glycol (EG) are mixed in a slurry preparation tank and then enter the first esterification reactor 1. After esterification, they enter the second esterification reactor 2 for further reaction. The generated esters are then sequentially introduced into the first pre-polycondensation reactor 3 and the second pre-polycondensation reactor 4 for preliminary polycondensation.

[0032] The discharge port of the second prepolymerization reactor 4 is connected to a diversion valve 401, which is connected to the high viscosity final polymerization reactor 5 and the low viscosity final polymerization reactor 6 through two branch pipes 402 respectively.

[0033] The length of the high-viscosity final polycondensation reactor 5 is greater than that of the low-viscosity final polycondensation reactor 6, and both are equipped with independent vacuum pump assemblies 8. The length of the high-viscosity final polycondensation reactor 5 is 13342 mm, and the vacuum degree of the supporting vacuum pump assembly 8 is controlled at 100 - 250 Pa, so that the melt residence time reaches 3 h to increase the melt viscosity. The length of the low-viscosity final polycondensation reactor 6 is 8025 mm, and the vacuum degree of the supporting vacuum pump assembly is controlled at 300 - 600 Pa, and the melt residence time is 1 h to control a lower viscosity. This length difference makes the melt final polycondensation residence time of the high-viscosity line longer than that of the low-viscosity line, thus being able to meet the production requirements of melts with different viscosities. When the catalyst content is the same, different vacuum degree controls combined with the difference in the reactor length can accurately control the viscosity of the melt;

[0034] Among them, the vacuum pump assembly 8 supporting the high-viscosity final polycondensation reactor 5 is mainly composed of a multi-stage vacuum pump group, a condensation device, and a vacuum pipeline. In the initial stage of the reaction, the low pumping speed vacuum pump is first started to slowly extract the air in the reactor, avoiding the violent boiling of the melt in the kettle due to too fast air extraction, which affects the product quality. As the reaction progresses, it is switched to a high pumping speed vacuum pump to achieve the high vacuum degree required for the reaction, promoting the efficient progress of the polycondensation reaction, and helping the small molecule by-products (such as ethylene glycol, water, etc.) in the melt to volatilize and remove more fully, thereby increasing the viscosity of the polyester melt. At the front end of the vacuum pump group, there is a scraper condenser. The scraper scrapes the condensable small molecule polymers from the pipe wall and flushes them into the EG storage tank with ethylene glycol (EG). At the same time, cold EG is used for spraying to cool the hot EG steam and make it flow back to the EG storage tank for recycling, reducing material loss. In addition, a jet condenser is also equipped to further reduce the steam temperature and enhance the vacuum pumping capacity, ensuring that the high-viscosity final polycondensation reaction proceeds in a stable high-vacuum environment and guaranteeing the stability of the product quality;

[0035] The vacuum pump assembly supporting the low-viscosity final polycondensation reactor 6 also includes a vacuum pump group, a condensation component, and a pipeline, but there are differences in equipment selection and operating parameters from the vacuum pump assembly of the high-viscosity reactor. Since the low-viscosity melt has relatively low requirements for the vacuum degree, the power and pumping rate of the vacuum pump group are adapted to this working condition to avoid the loss of effective components in the melt or the occurrence of unnecessary side reactions due to excessive vacuum pumping. In the condensation link, an efficient shell-and-tube condenser is used to increase the contact area between the steam and the coolant, improve the condensation efficiency, and quickly convert the condensable components in the steam into liquid for recycling. Different from the high-viscosity final polycondensation reactor, in the use of the jet pump of this vacuum pump assembly, the flow rate and pressure of the sprayed EG are adjusted according to the reaction characteristics to accurately control the vacuum degree, meet the requirements of the low-viscosity final polycondensation reaction, and ensure that the low-viscosity polyester melt smoothly completes the polycondensation reaction in a suitable vacuum environment without quality fluctuations caused by vacuum-related factors;

[0036] Both vacuum pump assemblies 8 are automatically regulated by a PLC control system. Based on the feedback data from the pressure sensor inside the reactor, the system precisely controls the start and stop of the vacuum pumps, adjusts the valve positions, and controls parameters such as the flow rate and temperature of the cooling medium. In addition, the vacuum pump assembly 8 is also equipped with a complete set of safety protection devices, such as a vacuum breaker valve. When the system pressure fluctuates abnormally or the equipment malfunctions, the valve can be opened quickly to prevent damage to the reactor and the production process caused by excessively high or low vacuum, thus ensuring the safe and stable operation of the entire production unit.

[0037] The discharge end of the high-viscosity final polycondensation reactor 5 is connected to the spinning unit and the chip production unit respectively through the first melt conveying pipe 508. The pipe length is shorter than the second melt conveying pipe 601, which can reduce the pressure loss and viscosity drop of the high-viscosity melt during the conveying process and ensure that the intrinsic viscosity of the high-viscosity polyester chips is maintained within the range of 0.800±0.010dl / g.

[0038] The discharge end of the low-viscosity final polycondensation reactor 6 is connected to the spinning unit and the chip production unit respectively through the second melt conveying pipe 601;

[0039] The chip production unit includes a pelletizer and a melt cooling mechanism, used to convert the melt after the final polycondensation reaction into polyester chips, specifically including the following components:

[0040] Melt cooling mechanism: Water or air cooling is used to rapidly cool the high-temperature melt (about 280-290℃) to the pelletizing temperature (about 80-100℃), to avoid degradation or viscosity change of the melt due to excessive residence time during the cooling process. Among them, the cooling mechanism for high-viscosity melts needs to have more precise temperature control (temperature difference ≤5℃) to prevent uneven cooling from causing differences in slicing performance.

[0041] Pelletizers: These are divided into underwater pelletizers and air pelletizers. The appropriate type should be selected based on the viscosity characteristics of the melt. Underwater pelletizers are usually used for high-viscosity melts, which use high-pressure water flow to assist in cutting and ensure that the slices are regular in shape (e.g., cylindrical, 3-4 mm in diameter and 3-5 mm in length). Air pelletizers can be used for low-viscosity melts to reduce the impact of moisture on the slices.

[0042] Drying equipment: including hot air drying tower or vacuum dryer, used to remove moisture from the surface of the slices (moisture content needs to be reduced to below 0.02%), to prevent melt degradation due to moisture during subsequent processing (such as spinning, injection molding);

[0043] Screening and conveying system: Unqualified slices (such as stuck or irregularly shaped slices) are screened by a vibrating screen, and qualified slices are conveyed to the slice silo for storage through a closed pipeline;

[0044] The spinning unit includes a spinning box and a melt distribution assembly for directly spinning low-viscosity melt into polyester fibers, specifically including the following components:

[0045] Melt distribution assembly: It consists of a main pipe, branch manifolds (distribution pipes) and metering pumps, which evenly distribute the melt to each spinning position (each spinning position corresponds to 1-8 spinnerets). When distributing low-viscosity melts, it is necessary to control the flow rate stability (fluctuation ≤2%) to avoid fiber linear density differences due to uneven distribution.

[0046] Spinning box: The internal heating device (such as hot oil circulation or electric heating) is installed to maintain the melt temperature at the temperature required for spinning (about 285-295℃), and the heat loss is reduced by the heat insulation layer. The box is also equipped with a melt filter (forming a double filtration with the filter of the second melt conveying pipe) to further remove impurities (particle size ≥20μm) in the melt and ensure that the spinneret is not blocked.

[0047] Spinneret: Different spinneret orifice shapes (circular, irregular) and orifice diameters are designed according to fiber type (such as filament, staple fiber). The conventional filament spinneret orifice diameter is 0.2-0.4mm. The melt is extruded through the spinneret to form nascent fibers (filaments).

[0048] Cooling air blowing device: Located below the spinneret, it uses side blowing or ring blowing to cool the nascent filament to below the glass transition temperature (about 60-80℃) to solidify and form it. The cooling air speed and temperature need to be precisely controlled (air speed 0.5-1.5m / s, air temperature 20-25℃) to avoid the filament from floating or cooling too quickly, which would cause excessive internal stress.

[0049] Winding device: includes traction roller, stretching roller and winding machine. The traction roller stretches the cooled filament (stretch ratio 2-5 times) to increase the fiber strength. Finally, the winding machine winds the filament into a roll (roll weight 5-10kg) for subsequent texturing or weaving.

[0050] like Figure 1 , Figure 3 , Figure 4 and Figure 5 As shown, in some embodiments, the high-viscosity final polycondensation reactor 5 is composed of an upper tank 501 and a lower tank 502 that cooperate with each other, and the low-viscosity final polycondensation reactor 6 has the same structure as the high-viscosity final polycondensation reactor 5.

[0051] Both the upper tank 501 and the lower tank 502 are integrally provided with an adjustment section tank 507. The two adjustment section tanks 507 are nested together and slidably connected, which facilitates the adjustment of the size of the reactor according to actual needs, better adapts to the use requirements, and improves the convenience of use. A sealing ring is provided at the overlapping part of the adjustment section tanks 507 to ensure a stable sealing connection. At the same time, a sealing lip plate is provided at the sliding joint end of the adjustment section tanks 507. The sealing lip plate abuts against the side wall of the corresponding adjustment section tank 507, and a sealing ring is placed at the abutment part of the sealing lip plate to form a stable and effective sealing connection.

[0052] Both the upper tank 501 and the lower tank 502 are equipped with end plates 503, and plug-in sleeves 504 are evenly arranged on the end plates 503. Connecting rods 505 are inserted into the plug-in sleeves 504, and the connecting rods 505 and the plug-in sleeves 504 are fixedly connected by fixing pins 506. During the adjustment process, the position of the upper tank 501 is adjusted by sliding on the lower tank 502 to realize the size adjustment operation of the reactor tank. After the adjustment is completed, the connecting rods 505 are inserted into the plug-in sleeves 504 on the two end plates 503, and then the fixing pins 506 are used to fix the connecting rods 505 to the plug-in sleeves 504, thus fixing the upper tank 501 and the lower tank 502 in the adjusted position.

[0053] like Figure 1 As shown, in some embodiments, a melt filter and a melt cooler are provided on the first melt delivery pipe 508. The melt filter can remove impurities in the melt, and the melt cooler helps to reduce the melt delivery temperature, while suppressing side reactions, effectively controlling the viscosity drop of the melt, and ensuring that the intrinsic viscosity of the low-viscosity melt is stable at 0.470±0.010 dl / g.

[0054] like Figure 1 and Figure 2 As shown, in some embodiments, an online colorant addition component 7 is also included. The outlet of the online colorant addition component 7 is connected to the feed end of the second esterification reactor 2. Since the high viscosity and low viscosity chips have different process parameters during production, the colors may differ. The online colorant addition component 7 can adjust the color value to ensure that the color difference is minimized during subsequent spinning.

[0055] The online toner addition component 7 includes a toner storage tank 701 and a mixer 702. The outlet of the mixer 702 is connected to the feed pipe of the second esterification reactor 2 through a feed pipe 704. A metering pump 703 is installed on the feed pipe 704. The metering pump 703 can accurately control the amount of toner added, while the mixer can fully mix the toner with the melt to ensure the effect of color value adjustment.

[0056] Based on the color value difference between high and low viscosity melts, the b value of high viscosity chips is 7.0-7.7 and that of low viscosity chips is around 4.16 when no toner is added. The amount of toner added is precisely controlled by metering pump 703, with an addition range of 0-1.200ppm, so that the final product has an L value ≥80.0 and a B value ≤5.0, ensuring color value consistency.

[0057] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A double final polycondensation reactor device capable of simultaneously producing high and low viscosity polyester melt, comprising a first esterification reactor (1), a second esterification reactor (2), a first pre-polycondensation reactor (3) and a second pre-polycondensation reactor (4) connected in sequence, characterized in that: The second pre-polycondensation reactor (4) is communicated with a shunt valve (401) at the discharge port, and the shunt valve (401) is respectively communicated with a high-viscosity final polycondensation reactor (5) and a low-viscosity final polycondensation reactor (6) through two branch pipes (402); The high-viscosity final polycondensation reactor (5) has a length greater than that of the low-viscosity final polycondensation reactor (6), and the two are respectively provided with independent vacuum pump assemblies (8); The discharge end of the high-viscosity final polycondensation reactor (5) is respectively connected to a spinning unit and a chip production unit through a first melt conveying pipe (508); The discharge end of the low-viscosity final polycondensation reactor (6) is respectively connected to a spinning unit and a chip production unit through a second melt conveying pipe (601).

2. The twin end-polycondensation reactor apparatus for simultaneously producing high and low viscosity polyester melt according to claim 1, characterized in that: The high-viscosity final polycondensation reactor (5) is composed of an upper tank body (501) and a lower tank body (502) cooperating with each other, and the low-viscosity final polycondensation reactor (6) has the same structure as the high-viscosity final polycondensation reactor (5); The upper tank body (501) and the lower tank body (502) are integrally provided with an adjusting section tank body (507), and the two adjusting section tank bodies (507) are sleeved and slidingly connected, and the adjusting section tank bodies (507) are provided with sealing rings at the overlapping parts; The upper tank body (501) and the lower tank body (502) are provided with end plates (503), and the end plates (503) are uniformly provided with plug-in sleeves (504), and connecting rods (505) are inserted into the plug-in sleeves (504), and the connecting rods (505) and the plug-in sleeves (504) are fixedly connected through fixed pins (506).

3. The twin end-polycondensation reactor apparatus for simultaneously producing high and low viscosity polyester melt according to claim 1, characterized in that: The melt filter (509) and the melt cooler (510) are arranged on the first melt conveying pipe (508).

4. The twin end-polycondensation reactor apparatus for simultaneously producing high and low viscosity polyester melt according to claim 1, characterized in that: An online toner adding assembly (7) is further included, and the discharge port of the online toner adding assembly (7) is connected to the feed end of the second esterification reactor (2).

5. The twin end-polycondensation reactor apparatus for simultaneously producing high and low viscosity polyester melt according to claim 4, characterized in that: The online toner adding assembly (7) includes a toner storage tank (701) and a mixer (702), and the discharge port of the mixer (702) is connected to the feed pipe of the second esterification reactor (2) through a feed pipe (704).

6. The twin end-polycondensation reactor apparatus for simultaneously producing high and low viscosity polyester melt according to claim 5, characterized in that: A metering pump (703) is arranged on the feed pipe (704).

7. The twin end-polycondensation reactor apparatus for simultaneously producing high and low viscosity polyester melt according to claim 1, characterized by: The chip production unit includes a granulator and a melt cooling mechanism; The spinning unit includes a spinning box and a melt distribution assembly.

Images