A nylon extraction device

Abstract

The utility model provides a nylon extraction device, comprising a pre-extraction tank, a water-material separation tank, and an extraction tower which are arranged in sequence, wherein a water inlet is arranged in the middle of the extraction tower, and two water inlets are arranged at the bottom, and the heights of the two water inlets at the bottom are different. By arranging the pre-extraction tank and the multiple water inlets, the nylon 56 slices are preheated before entering the extraction tower, and the temperature in the extraction tower is made more stable, thereby improving the extraction efficiency of the extraction tower and making the monomer extraction of nylon 56 more thorough.

Description

Technical Field

[0001] The utility model relates to a nylon production device, in particular to a nylon extraction device. Background Art

[0002] At present, the production of most nylons on the market depends on petroleum resources. However, as a non-renewable resource, excessive consumption of petroleum may not only lead to a crisis of resource depletion, but also cause a series of environmental problems during production and application. In order to meet this challenge, bio-based nylon 56 (also known as bio-based PA56 or bio-based polyamide 56) came into being. It is polypentamethylene adipate produced by the polymerization reaction of bio-based pentamethylenediamine and petroleum-based adipic acid.

[0003] During the initial development and commissioning of the drying and solid phase polymerization equipment for bio-based nylon 56, we found that the amount of monomer precipitation in the bio-based nylon 56 chips produced by the polymerization section was significantly higher than that in nylon 66 chips when they were directly dried and solid phase thickening. The precipitated monomers are prone to form crystals in the drying and solid phase thickening devices, blocking pipes and equipment, resulting in increased system resistance; and if these monomers are not effectively extracted, they may also cause broken or floating yarns in the spinning stage, affecting product quality.

[0004] Especially in the solid phase polymerization process, due to the high process temperature, the amount of monomer precipitation of bio-based nylon 56 is 5 to 8 times that of nylon 66, and it is difficult for conventional nylon 66 extraction devices to effectively extract the precipitated monomers. This situation not only puts a heavy burden on the continuous drying and solid phase viscosity increasing equipment, but also makes it difficult to control and improve the quality of the final slices.

[0005] Therefore, it is necessary to develop an extraction device suitable for bio-based nylon 56. Utility Model Content

[0006] In order to solve the above problems, the utility model provides a nylon 56 extraction device, and the specific scheme is as follows:

[0007] A nylon extraction device is characterized by comprising a pre-extraction tank, a water-material separation tank, and an extraction tower which are arranged in sequence, wherein a water inlet is arranged in the middle of the extraction tower, and two water inlets are arranged at the bottom, and the heights of the two water inlets at the bottom are different.

[0008] Optionally, the middle water inlet is connected to a cold water pipe, and of the two water inlets at the bottom, the upper water inlet is connected to a hot water pipe, and the lower water inlet is connected to a cold water pipe. A temperature measuring device is provided on the extraction tower, and the temperature measuring device is connected to a PLC control system, and the PLC control system is connected to the water inlet regulating valves of each water inlet.

[0009] Here, the "middle part" is not limited to the middle of the extraction tower, and two-thirds of the length of the middle section of the extraction tower can be understood as the middle part of the extraction tower. The "bottom" is not limited to the bottom of the extraction tower, and one-third of the length of the lower section of the extraction tower can be understood as the lower part of the extraction tower. At the same time, the "lower part" is located below the "middle part". The "connection" is not limited to direct connection by wires, and various wireless transmission methods should also be understood as "connection", as long as the signal transmission can be achieved. The "cold water" refers to water whose temperature is lower than the set water temperature of the extraction tower.

[0010] Optionally, a dehydration device is provided at the rear of the extraction tower.

[0011] Optionally, the nylon extraction device is arranged after the polymerization section and before the drying or solid phase polymerization section.

[0012] Optionally, the nylon extraction device is provided with a water circulation system, and the water circulation system circulates the water separated by the dehydration equipment to the extraction tower.

[0013] Optionally, the water circulation system includes a circulating water pump and a filter. The circulating water pipeline after filtration is divided into three routes. The three pipelines are arranged from bottom to top at the interfaces on the extraction tower. The first route directly leads to the bottom of the extraction tower, the second route is provided with a heat exchanger and leads to the bottom of the extraction tower, and the third route is provided with a heat exchanger and leads to the middle of the extraction tower.

[0014] Optionally, an overflow port is provided on the extraction tower.

[0015] Optionally, a heating area is provided on the tower body of the extraction tower.

[0016] Beneficial effects:

[0017] The utility model provides a pre-extraction tank so that the nylon 56 slices are preheated before entering the extraction tower, thereby preventing the low-temperature slices from affecting the temperature in the extraction tower; in addition, the provision of multiple water inlets allows the temperature in the extraction tower to be adjusted more quickly, so that the water temperature in the tower is always maintained at a better extraction temperature, thereby making the temperature in the extraction tower more stable, improving the working efficiency of the extraction tower, and making the monomer extraction of nylon 56 more thorough. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the overall schematic diagram of the nylon device of the utility model

[0019] The following are the descriptions of the reference numerals:

[0020] 100. Polymerization section 200. Drying section 310. Pre-extraction tank 311. Rotary valve 312. Mud pump 320. Water-material separation tank 330. Extraction tower 331. First water inlet 332. Second water inlet 333. Third water inlet 334. Overflow port 340. Centrifugal dryer 351. Dipping tank 352. Degassing tank 353 Circulating water pump 354. Filter 355. Plate heat exchanger 356. First heat exchanger 400. Fresh desalted water DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the embodiment of the utility model clearer, the technical scheme in the embodiment of the utility model will be further clearly and completely described in the following text in combination with the drawings. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. For the sake of clarity and conciseness, not all the features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual embodiment in order to achieve the specific goals of the developers. In order to avoid obscuring the utility model due to unnecessary details, only the device structure closely related to the scheme according to the utility model is described in the drawings and descriptions. In order to more clearly show the structure of the device described in the utility model, some structures are omitted in the drawings to highlight the characteristic structures of the important parts. In the following, for the convenience of description, unless otherwise specified, slices refer to bio-based nylon 56 slices.

[0022] Example 1

[0023] This embodiment provides a bio-based nylon 56 extraction device, which is arranged after the polymerization section 100 and before the drying section 200. Figure 1 As shown, the bio-based nylon 56 extraction device includes a pre-extraction tank 310, a rotary valve 311, a mud pump 312, a water-material separation tank 320, an extraction tower 330, a centrifugal dryer 340, and a water circulation system which are arranged in sequence.

[0024] The volume of the extraction tower 330 is 35m 3The extraction tower 330 is provided with a first water inlet 331, a second water inlet 332 and a third water inlet 333 in the middle of the tower body. The first water inlet 331 is provided in the middle of the tower body, and the second water inlet 332 and the third water inlet 333 are provided at the bottom of the tower body, wherein the second water inlet 332 is higher than the third water inlet 333. The extraction tower 330 is provided with a temperature measuring device not shown in the figure. There are 6 temperature measuring devices, which are evenly arranged in the height direction of the extraction tower 330. The temperature measuring device is connected to the PLC control system, and the PLC control system is connected to the water inlet regulating valve of each water inlet. The temperature measuring device can automatically detect the water temperature in the extraction tower and feed it back to the PLC control system, and then the PLC control system outputs a signal to the regulating valve of each water inlet to adjust the water inlet, thereby realizing the automatic control of the water temperature in the extraction tower 330. The tower body of the extraction tower 330 is provided with a heating area not shown in the figure. The heating area is a heating layer, which is used for heating and heat preservation of the entire extraction tower 330. An overflow port 334 is provided at the top of the extraction tower 330. The water discharged from the overflow port 334 can be directly discharged to the sewage treatment system, or can be treated to participate in the water circulation of the extraction device.

[0025] The centrifugal dryer 340 is provided with a slice outlet and a water outlet. The slice outlet delivers the dried slices to the drying section 200, and the water outlet is connected to the water circulation system. The water circulation system includes an immersion tank 351, a degassing tank 352, a circulating water pump 353, and a filter 354 connected in sequence by pipelines. The circulating water pipeline filtered by the filter 354 is divided into three routes. One route is connected to the first water inlet 331 of the extraction tower 330 after heat exchange and cooling with circulating cooling water through a plate heat exchanger 355, one route is connected to the second water inlet 332 after heat exchange with high-temperature steam through a heat exchanger 356, and one route is directly connected to the third water inlet 333.

[0026] During the operation of the bio-based nylon extraction device of this embodiment, the bio-based nylon 56 slice particles pelletized by the pelletizing device of the polymerization section 100 are transported to the pre-extraction tank 310. In the pre-extraction tank 310, the bio-based nylon 56 slices and the hot water are in countercurrent. The slices move downward under the action of gravity, and the hot water flows from bottom to top and flows to the concentration system through the overflow port of the pre-extraction tank. In this process, the 90°C hot water (desalted water) and the bio-based nylon 56 slices undergo a heat transfer process, and the slice temperature rises. As the temperature rises, the small molecular substances remaining in the polymerization section precipitate outward and enter the hot water. Because the pre-extraction tank 310 is small in size and has a limited residence time, the pre-extraction tank 310 here mainly plays a preheating role, that is, preheating the slices from the polymerization section. If the slices directly enter the extraction tower, the slices heat up slowly, which may cause the slices to fail to meet the heating requirements, affecting the temperature of the slices in the extraction tower, and further affecting the extraction efficiency. Therefore, the slices are preliminarily heated and pre-extracted in the pre-extraction tank 310. The preheated slices are sucked into the mud pump 312 after passing through the rotary valve 311 set below the pre-extraction tank 310. In this embodiment, the rotary valve plays a metering role and is used to control the output. Under the action of the mud pump 312, the slices and hot water are transported to the water-material separation tank 320 together, and the slices and hot water are separated in the water-material separation tank 320. After separation, the slices enter the extraction tower 330, which is filled with 90-95°C hot water. The extraction tank 330 has a large volume, usually more than 15 times larger than the volume of the pre-extraction tank 310, so that the slices can stay in the extraction tower 330 for more than 12 hours. During the 12 hours of slow flow from top to bottom, a large amount of small molecular weight monomers diffuse outward from the inside of the slices, and are finally carried away by the water flow from bottom to top. The water flow carrying small molecular weight monomers overflows from the overflow port of the extraction tower 330. The overflowing water flow can enter the concentration section for concentration, and the concentrated small molecular weight substances are then transported to the liquid phase polymerization section to participate in the polymerization reaction. The water temperature in the extraction tower decreases gradually from bottom to top, so as to ensure that the small molecular weight substances inside the bio-based nylon 56 slices are well precipitated to the surface during the flow from top to bottom, and then enter the hot water. In other words, fresh hot water is continuously added to the extraction tower 330 from the bottom of the extraction tower 330. The concentration of small molecular weight substances in the hot water at the bottom of the extraction tower 330 is the lowest, and the concentration of small molecular weight substances in the hot water at the top is the highest.

[0027] After the extraction, the slices are transported to the centrifugal dryer 340 at a high place through a pipeline. Under the action of centrifugal force, the slices and water are separated. The moisture content of the slices after separation is controlled at about 7000-8000ppm, and then the slices are transported to the drying or solid phase viscosity increasing section. The water separated by the centrifugal dryer 340 enters the immersion tank 351 under the action of gravity. Because the fresh desalted water added is at room temperature, it is difficult to adjust the water temperature by the subsequent temperature control equipment alone. Therefore, the immersion tank 351 needs to adjust the temperature of the circulating water in advance. Two sets of heat exchange devices not shown in the figure are arranged inside the immersion tank 351, one set is passed through high-temperature steam, and the other set is passed through circulating cooling water, so as to realize the automatic control of the water temperature in the immersion tank 351. The fresh desalted water 400 added to the whole extraction system is added to the inlet pipe of the immersion tank 351, and enters the degassing tank 352 after temperature adjustment through the immersion tank 351 together with the water from the centrifugal dryer 340. The water after the degassing tank 352 enters the circulating water pump 353, and the water circulation system is powered by the circulating water pump 353. When the solubility of the extracted low molecular weight substances in hot water reaches saturation, they will appear solid and exist in hot water in a flocculent or viscous state. Therefore, a filter 354 is set at the outlet of the circulating water pump 353 to filter the flocculent or viscous low molecular weight substances. The filtered circulating water is divided into three paths, one of which directly enters the bottom of the extraction tower 330 and is connected to the third water inlet 333; one of which enters the bottom of the extraction tower 330 after heat exchange with high temperature steam through the first heat exchanger 356 and is connected to the second water inlet 332; the other of which enters the middle of the extraction tower 330 after cooling through the plate heat exchanger 355 and is connected to the first water inlet 331. Among them, the temperature of the water introduced into the first water inlet 331 is about 20°C, the hot water introduced into the second water inlet 332 is about 98°C, and the temperature of the water introduced into the third water inlet 333 is about 80°C. The hot water introduced into the second water inlet 332 flows upward in the extraction tower 330, mainly for extraction; the water temperature introduced into the first water inlet 331 is relatively low, which is used to regulate the water temperature in the extraction tower 330 to prevent the temperature in the upper part of the extraction tower from being too high; the water flow temperature introduced into the third water inlet 333 is relatively low relative to the extraction temperature, and the water flows downward at the bottom of the extraction tower 330, carrying the extracted slices to the centrifugal dryer 340, which plays a role in cooling the extracted slices and adjusting the liquid level of the extraction tower. The three water inlet volumes are automatically detected by the temperature measuring device on the extraction tower, and the water temperature in the extraction tower is fed back to the PLC control system, and then the PLC control system outputs signals to the regulating valves set on the three waterways to adjust the water inlet volume, thereby realizing automatic control of the water temperature in the extraction tower 330. The water temperature can be adjusted slowly by only setting a heating layer on the outer layer of the extraction tower. In contrast, in this embodiment, three water inlets with different temperatures can adjust the water temperature in the extraction tower 330 more quickly and accurately, thereby avoiding uneven outer wall temperature and internal temperature and achieving better extraction effect.

[0028] The equipment of this embodiment has been put into production, the system runs stably and automatically, the precipitation amount of small molecular weight substances is 3‰ to 4‰, and the extraction effect is remarkable.

Claims

1. A nylon extraction device, characterized in that: The invention comprises a pre-extraction tank, a water-material separation tank and an extraction tower which are arranged in sequence. The extraction tower has a water inlet in the middle and two water inlets at the bottom. The heights of the two water inlets at the bottom are different.

2. The nylon extraction device according to claim 1, characterized in that: The middle water inlet is connected to the cold water pipe. Among the two water inlets at the bottom, the upper water inlet is connected to the hot water pipe, and the lower water inlet is connected to the cold water pipe. A temperature measuring device is arranged on the extraction tower, and the temperature measuring device is connected to the PLC control system. The PLC control system is connected to the water inlet regulating valve of each water inlet.

3. The nylon extraction device according to claim 1, characterized in that: A dehydration device is arranged at the rear of the extraction tower.

4. The nylon extraction device according to claim 1, characterized in that: The nylon extraction device is arranged after the polymerization section and before the drying or solid phase polymerization section.

5. The nylon extraction device according to claim 3, characterized in that: The nylon extraction device is provided with a water circulation system, and the water circulation system circulates and transports the water separated by the dehydration equipment to the extraction tower.

6. The nylon extraction device according to claim 5, characterized in that: The water circulation system includes a circulating water pump and a filter. The circulating water pipeline after filtration is divided into three routes. The three routes are arranged from bottom to top at the interfaces on the extraction tower. The first route directly leads to the bottom of the extraction tower, the second route is provided with a heat exchanger and leads to the bottom of the extraction tower, and the third route is provided with a heat exchanger and leads to the middle of the extraction tower.

7. The nylon extraction device according to claim 1, characterized in that: The extraction tower is provided with an overflow port.

8. The nylon extraction device according to claim 1, characterized in that: A heating area is arranged on the tower body of the extraction tower.

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