Production device and method of multi-configuration nylon

Abstract

A multi-configuration nylon production device comprises a polymerization system and a pelletizing system, the polymerization system comprises a first-stage concentration kettle, a second-stage concentration kettle and a polymerization kettle, a discharge port of the first-stage concentration kettle supplies materials to the second-stage concentration kettle, a discharge port of the second-stage concentration kettle supplies materials to the polymerization kettle, a pressurization pipe is arranged at the top of the polymerization kettle, a polymerization kettle gas phase outlet is formed, and the polymerization kettle gas phase outlet is communicated with the pressurization pipe. The pelletizing system comprises a brace pelletizing mechanism and a die surface pelletizing mechanism, the brace pelletizing mechanism comprises a cast strip head and a pelletizing machine, a discharge port of the cast strip head supplies materials to the pelletizing machine through a cooling tank, the die surface pelletizing mechanism comprises a melt booster pump and a cutter, a discharge port of the melt booster pump supplies materials to the cutter through a die head, the cutter discharges materials through a slice cooling crystallizer, and the melt booster pump is connected with the die head. And the feed port of the casting head or the feed port of the melt booster pump is detachably connected with the discharge port of the polymerization kettle. The device is simple in structure and convenient to operate, nylon products of different configurations can be produced through one device, and the production cost of enterprises can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical industry field, in particular to a production device and method of multi-configuration nylon. BACKGROUND

[0002] Nylon is a series of high molecular materials with amide bond, which is one of the five engineering plastics. Due to its similar process characteristics, a variety of configuration nylon series resins are derived, which has the characteristics of high wear resistance, high strength, good solvent resistance, etc. It is widely used in the fields of automobile, electronic appliances, clothing fibers and high barrier films. With excellent mechanical strength, wear resistance, heat resistance, and lightweight characteristics, it plays a key role in many fields and has a large market demand.

[0003] With the development of social economy, the demand for different configurations of nylon is increasing, such as high barrier nylon, transparent nylon, soft nylon, alcohol-soluble nylon, etc. These nylons have large differences in physical properties, such as melt dynamic viscosity, which differs by tens of times, and large differences in crystallinity, some of which do not crystallize. Therefore, different cutting machines need to be selected when cutting, resulting in large equipment investment and low equipment utilization. In addition, due to the unique performance of different configurations of nylon and the high requirement on polymerization process, the traditional production process is not suitable for the production of multi-configuration nylon.

[0004] Therefore, how to design a process suitable for the production of multi-configuration nylon resin and improve the application of multi-configuration nylon in high-end quality is a problem to be solved by those skilled in the art. SUMMARY

[0005] One of the purposes of the present application is to overcome the shortcomings of the prior art and provide a production device for multi-configuration nylon, which has a simple structure, is easy to operate, can produce nylon products of different configurations with one device, and can effectively reduce the production cost of enterprises.

[0006] The second purpose of the present application is to provide a method for processing nylon using the above production device, which can switch between different configurations of nylon production at low cost and has low production cost.

[0007] The technical scheme for achieving one of the objects of the present application is: a multi-configuration nylon production device, comprising a polymerization system and a pelletizing system, the polymerization system comprises a first concentration kettle, a second concentration kettle, and a polymerization kettle, the feed inlet of the first concentration kettle is connected with a source of nylon salt aqueous solution, the discharge outlet of the first concentration kettle supplies the second concentration kettle, the discharge outlet of the second concentration kettle supplies the polymerization kettle, the top of the polymerization kettle is provided with a pressurizing pipe connected with a high-pressure gas source and a gas-phase outlet of the polymerization kettle connected with a negative pressure source, the pelletizing system comprises a drawbar pelletizing mechanism and a die face pelletizing mechanism, the drawbar pelletizing mechanism comprises a strip casting head and a pelletizer, the discharge outlet of the strip casting head supplies the pelletizer through a cooling tank, the die face pelletizing mechanism comprises a melt booster pump and a cutter, the discharge outlet of the melt booster pump supplies the cutter through a die head, the cutter discharges through a slice cooling crystallizer, and the feed inlet of the strip casting head or the feed inlet of the melt booster pump is detachably connected with the discharge outlet of the polymerization kettle.

[0008] The second concentration kettle is located below the first concentration kettle and above the polymerization kettle, the first concentration kettle, the second concentration kettle, and the polymerization kettle are all provided with heat exchangers, the top of the second concentration kettle is provided with a first additive inlet, and the top of the polymerization kettle is provided with a second additive inlet, the top of the first concentration kettle is provided with a gas-phase outlet of the first concentration kettle, which returns through a condenser, and the top of the second concentration kettle is provided with a gas-phase outlet of the second concentration kettle, which provides heat for the heat exchanger of the first concentration kettle.

[0009] The gas-phase outlet of the polymerization kettle is connected with a negative pressure source through the shell side of a tail gas heat exchanger, the top of the shell side of the tail gas heat exchanger is provided with a sprayer, the bottom of the shell side of the tail gas heat exchanger is provided with a settling tank, and the settling tank provides spraying water for the sprayer through a polymerization washing pump and a washing water cooler.

[0010] The bottom of the shell side of the tail gas heat exchanger is provided with a liquid seal pipe extending downward, the liquid seal pipe extends below the liquid level of the settling tank, and the liquid seal height is greater than or equal to 10 m.

[0011] The cooling tank comprises first and second water spraying cooling tanks with the same extension direction, the strip casting head is located on one side of the discharge outlet of the polymerization kettle, and the discharge outlet of the strip casting head supplies the pelletizer through the first and second water spraying cooling tanks.

[0012] The first water spraying cooling tank moves vertically along the extension direction and is dislocated from the second water spraying cooling tank along the vertical direction, so that a switching space is formed between the polymerization kettle and the second water spraying cooling tank, and the melt booster pump, the die head, and the cutter are arranged on a moving platform and can enter and exit the switching space.

[0013] A water distributor and a dehydration dryer are further included, and the discharge outlets of the pelletizer and the slice cooling crystallizer both supply the dehydration dryer through the water distributor.

[0014] The second technical solution to achieve the objective of this invention is: a method for processing nylon using any of the production devices described in 1-7, comprising the following steps: 1) The nylon salt solution is concentrated sequentially through a primary concentration vessel and a secondary concentration vessel, and a sodium hypophosphite solution is added through the first additive inlet to obtain a nylon salt slurry. 2) The nylon salt slurry is fed into the polymerization reactor. The pressure of the polymerization reactor is controlled at 1.6-1.9 MPa and the temperature at 250-270℃. The polymerization reaction is carried out for 30-90 minutes. The pressure is then controlled to atmospheric pressure. After adjusting the temperature to 245-290℃, the pressure is controlled at 0.05-0.06 MPa. The polymerization reaction is carried out for 10-30 minutes to obtain the melt material. 3) Based on the material characteristics of the melt, connect the inlet of the casting head or the melt booster pump to the outlet of the polymerization reactor, and pressurize the polymerization reactor to 0.6-0.9 MPa through the pressurization pipe, and then cut the discharged material into pellets or slices.

[0015] Preferably, in step 1), the concentration ratio of the primary concentration vessel is 1.14-1.30, the concentration ratio of the secondary concentration vessel is 1.15-1.35, and sodium hypophosphite is added in the form of an aqueous solution with a concentration of 10 wt%. The amount of sodium hypophosphite aqueous solution added is 0.03% of the mass of the nylon pellets or slices.

[0016] Further, in step 2), caprolactam is added to the polymerization reactor at an amount of 2-10% of the mass of the nylon pellets or slices.

[0017] The above technical solution has the following beneficial effects: 1. A multi-configuration nylon production apparatus includes a polymerization system and a pelletizing system. The polymerization system uses nylon brine solution as raw material to synthesize nylon, while the pelletizing system pelletizes melt materials with different properties. The polymerization system includes a primary concentration kettle, a secondary concentration kettle, and a polymerization kettle. The inlet of the primary concentration kettle is connected to a nylon brine solution source, and the outlet of the primary concentration kettle supplies material to the secondary concentration kettle. The nylon brine solution undergoes primary concentration in the primary concentration kettle, and the concentrated nylon brine solution is then sent to the secondary concentration kettle for further concentration to obtain a concentrated material suitable for polymerization. The outlet of the secondary concentration kettle supplies material to the polymerization kettle, where the concentrated nylon brine solution polymerizes to obtain the melt material. The top of the polymerization kettle is equipped with a pressurization pipe connected to a high-pressure gas source, and a gas phase outlet of the polymerization kettle is connected to a negative pressure source to control the pressure of the polymerization kettle. The pelletizing system includes a strip pelletizing mechanism and a die-face pelletizing mechanism. Nylons that are not easily crystallized and have poor heat transfer properties can use a die-face pelletizing structure, while nylons with other properties can use a strip pelletizing mechanism. The strip pelletizing mechanism includes a casting strip head and a pelletizer. The discharge port of the casting strip head supplies material to the pelletizer via a cooling tank. The die-face pelletizing mechanism includes a melt booster pump and a cutter. The discharge port of the melt booster pump supplies material to the cutter via the die head. The cutter discharges material through a slice cooling crystallizer. The inlet of the casting strip head or the inlet of the melt booster pump is detachably connected to the outlet of the polymerization reactor. Depending on the differences in the physical properties of the melt material in the polymerization reactor, the casting strip head or the melt booster pump can be flexibly selected for connection to produce nylon products with different configurations, effectively reducing the production cost of nylon.

[0018] 2. The secondary concentration vessel is located below the primary concentration vessel and above the polymerization vessel. It utilizes gravity for sequential discharge and feeding, reducing material handling costs. All three vessels—primary, secondary, and polymerization—are equipped with heat exchangers. The secondary concentration vessel has a first additive inlet at its top, and the polymerization vessel has a second additive inlet at its top. The primary concentration vessel has a vapor outlet at its top, which is refluxed via a condenser, improving material concentration efficiency while minimizing raw material loss. The secondary concentration vessel also has a vapor outlet at its top, providing heat to the heat exchanger in the primary concentration vessel. Utilizing the steam generated from material concentration in the secondary concentration vessel as heat for the primary concentration vessel's heat exchanger effectively reduces energy consumption in nylon production.

[0019] 3. The gas phase outlet of the polymerization reactor is connected to a negative pressure source via the shell side of a tail gas heat exchanger. A sprayer is installed at the top of the shell side of the tail gas heat exchanger, and a settling tank is installed at the bottom of the shell side. The settling tank provides spray water to the sprayer via a polymerization washing pump and a washing water cooler. Most of the moisture in the polymerization tail gas is removed by the washing water spray first, and then the negative pressure source draws a vacuum. This can effectively reduce the energy consumption of vacuuming, greatly reduce the content of small polymer molecules in the exhaust gas of the negative pressure source, and reduce the load of subsequent tail gas treatment.

[0020] 4. The bottom of the shell side of the exhaust gas heat exchanger is equipped with a downward-extending liquid seal pipe that extends to below the liquid level in the settling tank, and the liquid seal height is greater than or equal to 10m. This effectively prevents washing water from entering the polymerization reactor and ensures the safe reaction of the polymerization reaction system.

[0021] 5. The cooling tank includes a first water spray cooling tank and a second water spray cooling tank with the same extension direction. The casting strip head is located on one side of the discharge port of the polymerization reactor. The discharge port of the casting strip head supplies material to the pelletizer through the first water spray cooling tank and the second water spray cooling tank. The first water spray cooling tank moves vertically along the extension direction and is offset from the second water spray cooling tank in the vertical direction, so that a switching space is formed between the polymerization reactor and the second water spray cooling tank. The melt booster pump, the die head, and the cutter are set on the moving platform and can enter and exit the switching space. The first water spray cooling tank can be moved to connect the first water spray cooling tank and the second water spray cooling tank end to end to cool the discharge of the casting strip head for nylon pelletizing. Alternatively, the first water spray cooling tank can be moved to free up the switching space and the moving platform can be transferred to the switching space to facilitate the connection of the melt booster pump to the discharge port of the polymerization reactor for nylon slicing.

[0022] 6. It also includes a water separator and a dehydration dryer. The discharge ports of the pelletizer and the slice cooling crystallizer are both fed to the dehydration dryer through the water separator. That is, the pelletizer and the slice cooling crystallizer share a set of water separator and dryer, which reduces the investment in nylon production equipment.

[0023] 7. The production method of this invention involves secondary concentration of the nylon salt aqueous solution. Through this step-by-step concentration, the nylon salt aqueous solution is concentrated, preventing self-polymerization during the concentration stage and shortening its residence time in each concentration vessel, thus avoiding coking and ensuring the quality of the prepared nylon product. This also improves the utilization rate of raw materials. Furthermore, the primary concentration uses the steam generated from the secondary concentration as a heat source, reducing steam consumption by more than 30%. Adding sodium hypophosphite aqueous solution during the secondary concentration process effectively improves the antioxidant properties of the nylon salt aqueous solution. By controlling the heating, pressurization, and depressurization of the polymerization vessel, the molecular weight distribution of the prepared nylon is made uniform, making it easier to control the nylon viscosity and ensuring the quality of the prepared nylon. The polymerized melt is pressurized to 0.6-0.9 MPa based on its physical properties to provide power for pelletizing. The material is then discharged to the casting head for forming or further pressurized by a melt booster pump before being sent to the die head for forming, effectively meeting the production needs of different nylon configurations.

[0024] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2This is a layout diagram of the pelletizing mechanism and the die-face pelletizing mechanism of the present invention.

[0026] In the attached diagram, 1 is the polymerization system, 2 is the pelletizing system, 3 is the primary concentration vessel, 4 is the secondary concentration vessel, 5 is the polymerization vessel, 6 is the pressurization pipe, 7 is the gas phase outlet of the polymerization vessel, 8 is the strip pelletizing mechanism, 9 is the die-face pelletizing mechanism, 10 is the casting strip head, 11 is the pelletizer, 12 is the cooling tank, 121 is the first water spray cooling tank, 122 is the second water spray cooling tank, 13 is the melt booster pump, 14 is the cutter, 15 is the die head, 16 is the slice cooling crystallizer, 17 is the first additive inlet, 18 is the second additive inlet, 19 is the gas phase outlet of the primary concentration vessel, 20 is the condenser, 21 is the gas phase outlet of the secondary concentration vessel, 22 is the tail gas heat exchanger, 23 is the sprayer, 24 is the settling tank, 25 is the polymerization washing pump, 26 is the washing water cooler, 27 is the liquid seal pipe, 28 is the switching space, 29 is the water separator, and 30 is the dehydration dryer. Detailed Implementation

[0027] In this invention, devices without a specified structure are typically made using conventional equipment from the chemical industry, and devices without a specified installation and connection method are typically installed and connected using conventional methods from the chemical industry or according to the manufacturer's instructions. Example 1

[0028] See Figure 1 and Figure 2The production apparatus for multi-configuration nylon includes a polymerization system 1 and a pelletizing system 2. The polymerization system 1 includes a primary concentration vessel 3, a secondary concentration vessel 4, and a polymerization vessel 5. Specifically, the secondary concentration vessel 4 is located below the primary concentration vessel 3 and above the polymerization vessel 5, and is fed by gravity. The inlet of the primary concentration vessel 2 is connected to a nylon brine solution source. The outlet of the primary concentration vessel 3 supplies material to the secondary concentration vessel 4, and the outlet of the secondary concentration vessel 4 supplies material to the polymerization vessel 5. The top of the polymerization vessel 5 is equipped with a pressurization pipe 6 connected to a high-pressure gas source and a polymerization vessel gas phase outlet 7 connected to a negative pressure source. Obviously, both the pressurization pipe and the polymerization vessel gas phase outlet are equipped with valves to control their opening and closing and degree of opening. The high-pressure gas source is a high-pressure nitrogen source. To meet actual needs, heat exchangers are provided in the primary concentration vessel 3, the secondary concentration vessel 4, and the polymerization vessel 5. In this embodiment, heat exchangers are heat exchange coils, and stirrers are provided in the primary concentration vessel, the secondary concentration vessel, and the polymerization vessel. The top of the secondary concentration vessel 4 is equipped with a first additive inlet 17, and the top of the polymerization vessel 5 is equipped with a second additive inlet 18. The top of the primary concentration vessel 3 is equipped with a primary concentration vessel gas phase outlet 19 and a condenser 20 is installed. The top of the secondary concentration vessel 4 is equipped with a secondary concentration vessel gas phase outlet 19. The gas phase outlet 21 provides heat (steam) to the heat exchanger of the primary concentration vessel 3. The gas phase outlet 7 of the polymerization vessel is connected to a negative pressure source via the shell side of a tail gas heat exchanger 22. Specifically, the tail gas heat exchanger is a shell-and-tube heat exchanger, arranged vertically. The gas phase outlet of the polymerization vessel is connected to the lower part of the shell side of this shell-and-tube heat exchanger, and the upper part of the shell side of the shell-and-tube heat exchanger is connected to a negative pressure source, typically a vacuum pump. A sprayer 23 is installed at the top of the shell side of the tail gas heat exchanger 22. A settling tank 24 is provided at the bottom of the shell side of the heat exchanger 22. In this embodiment, a downward-extending liquid seal pipe 27 is provided at the bottom of the shell side of the exhaust gas heat exchanger 22. The liquid seal pipe 27 extends to below the liquid level of the settling tank 24, and the liquid seal height is greater than or equal to 10m. That is, the vertical height of the liquid seal pipe in the settling tank is not less than 10m. The settling tank 24 provides spray water to the sprayer 23 through the polymerization washing pump 25 and the washing water cooler 26. In addition, an overflow port is provided on the side wall of the settling tank. The pelletizing system 2 includes a strip pelletizing mechanism 8 and a die-face pelletizing mechanism 9. The strip pelletizing mechanism 8 includes a casting strip head 10 and a pelletizer 11. The discharge port of the casting strip head 10 supplies material to the pelletizer 11 through the cooling tank 12. In this embodiment, the material is used to feed the pelletizer 11. Figure 2As shown, the bottom corresponds to the south and the right corresponds to the east. The casting head is located on the south side of the polymerization reactor. The cooling tank 12 includes a first water spray cooling tank 121 and a second water spray cooling tank 122 extending in the same direction. Both extend in the east-west direction and are located on the east side of the polymerization reactor. The first water spray cooling tank can be moved in the north-south direction and offset from the second water spray cooling tank 122 in the vertical direction, so that a switching space 28 is formed between the polymerization reactor 5 and the second water spray cooling tank 122. The pelletizer is a rotary pelletizer located on the south side of the second water spray cooling tank. The discharge port of the casting head 10 feeds the pelletizer 11 through the first water spray cooling tank 121 and the second water spray cooling tank 122. The die-cutting mechanism 9 includes a melt booster pump 13 and a cutter 14. The outlet of the melt booster pump 13 supplies material to the cutter 14 via the die head 15, and the cutter 14 discharges material through the slice cooling crystallizer 16. Specifically, the melt booster pump 13, die head 15, and cutter 14 are mounted on a moving platform and can enter and exit the switching space 28. Typically, an adapter and a screen changer are also installed sequentially between the melt booster pump and the die head. The inlet of the casting strip head 10 or the inlet of the melt booster pump 13 is detachably connected to the outlet of the polymerization reactor. To meet the drying requirements of the granulated nylon or sliced ​​nylon, a water separator 29 and a dehydrator 30 are also included. The outlets of the pelletizer 11 and the slice cooling crystallizer 16 both supply material to the dehydrator 30 via the water separator 29. Example 2

[0029] Nylon was synthesized using the production apparatus of Example 1, and the steps were as follows: 1) The Nylon 66 salt solution (57% mass concentration) produced by the reaction of adipic acid and hexamethylenediamine is sent to the primary concentration kettle through pipeline, with a one-time input of 5t. Under the heating and evaporation of the production steam in the secondary concentration kettle, the Nylon 66 salt is concentrated to 65% (wt%). The concentrated Nylon 66 salt flows into the secondary concentration kettle by gravity.

[0030] 2) Sodium hypophosphite aqueous solution (concentration of 10wt%, added amount of 0.03% of nylon pellet product) is added to the secondary concentration tank through the first additive inlet. Under the heating and evaporation of saturated steam, the nylon 66 salt solution is concentrated to 80% (wt%) in about 20 minutes. The concentrated nylon 66 salt flows into the polymerization tank by gravity.

[0031] 3) The secondary concentrated nylon 66 salt solution is introduced into the polymerization reactor. The polymerization temperature and pressure are increased until the pressure inside the reactor reaches about 1.8 MPaG. The pressure is maintained at 1.8 MPaG. The polymerization temperature is slowly increased to about 260-270℃ and the pressure is maintained for 30 minutes. The pressure inside the polymerization reactor is gradually reduced to atmospheric pressure. The temperature inside the polymerization reactor is slowly increased to 280-290℃. At 290℃, the pressure inside the reactor is reduced to 0.05 MPaA, and polymerization continues for 10 minutes.

[0032] 4) Adjust the nitrogen pipeline pressure on the polymerization reactor to 0.6 MPaG, connect the feed port of the casting strip head to the discharge port of the polymerization reactor, move the first water spray cooling tank to the switching space, and follow the conventional pelletizing process to pull the melt material into strips, cool, pelletize, separate water, and dry it to obtain Nylon 66 particles with a moisture content of less than 0.3%. Example 3

[0033] Nylon was synthesized using the production apparatus of Example 1, and the steps were as follows: 1) A 50% (wt%) salt solution generated by equimolar amounts of hexamethylenediamine / isophthalic acid and hexamethylenediamine / terephthalic acid is sent to the primary concentration vessel via pipeline, with a single input of 5t. Under the heating and evaporation of the production steam in the secondary concentration vessel, the PA6I / 6T salt is concentrated to 62% (wt%). The concentrated PA6I / 6T salt then flows into the secondary concentration vessel by gravity.

[0034] 2) Sodium hypophosphite aqueous solution (concentration of 10wt%, added amount of 0.03% of nylon chip product) is added to the secondary concentration vessel through the first additive inlet. Under the heating and evaporation of saturated steam, the PA6I / 6T salt solution is concentrated to 80% (wt%) in about 40 minutes. The concentrated nylon 66 salt flows into the polymerization vessel by gravity.

[0035] 3) The PA6I / 6T salt solution after secondary concentration is introduced into the polymerization reactor. The polymerization temperature and pressure are increased until the pressure inside the reactor reaches about 1.9 MPaG. The pressure is maintained at 1.9 MPaG. The polymerization temperature is slowly increased to about 260-270℃ and the pressure is maintained for 60 minutes. The pressure inside the polymerization reactor is gradually reduced to atmospheric pressure. The temperature inside the polymerization reactor is slowly increased to 280-285℃. At 285℃, the pressure inside the reactor is reduced to 0.06 MPaA, and polymerization continues for 30 minutes.

[0036] 4) Adjust the nitrogen pipeline pressure on the polymerization reactor to 0.8 MPaG, move the mobile platform to the switching space, connect the inlet of the melt booster pump to the outlet of the polymerization reactor, and pressurize, filter, form, slice, cool and crystallize, separate water and dry the melt material according to the conventional slicing process to obtain nylon sheets. Example 4

[0037] Nylon was synthesized using the production apparatus of Example 1, and the steps were as follows: 1) A 50% (wt%) salt solution generated by equimolar amounts of hexamethylenediamine and terephthalic acid is piped to the primary concentration vessel with a single input of 5t. Under the heating and evaporation of the steam produced in the secondary concentration vessel, the nylon salt is concentrated to 62% (wt%). The concentrated nylon salt then flows into the secondary concentration vessel by gravity.

[0038] 2) Sodium hypophosphite aqueous solution (concentration of 10wt%, added amount of 0.03% of nylon chip product) is added to the secondary concentration vessel through the first additive inlet. Under the heating and evaporation of saturated steam, the PA6I / 6T salt solution is concentrated to 80% (wt%) in about 40 minutes. The concentrated nylon salt flows into the polymerization vessel by gravity.

[0039] 3) Caprolactam (6% of the nylon chip product weight) is added to the polymerization reactor through the second additive inlet. The secondary concentrated salt solution enters the polymerization reactor. The polymerization temperature and pressure are increased until the pressure inside the reactor reaches about 1.5 MPaG. The pressure is maintained at 1.5 MPaG. The polymerization temperature is slowly increased to about 250-260℃. The pressure is maintained for 60 minutes. The pressure inside the polymerization reactor is gradually reduced to atmospheric pressure. The temperature inside the polymerization reactor is controlled at 245-255℃. At 245-255℃, the pressure inside the reactor is reduced to 0.06 MPaA. The polymerization continues for 10 minutes.

[0040] 4) Adjust the nitrogen pipeline pressure on the polymerization reactor to 0.7 MPaG, move the mobile platform to the switching space, connect the inlet of the melt booster pump to the outlet of the polymerization reactor, and pressurize, filter, shape, slice, cool and crystallize, separate water and dry the melt material according to the conventional slicing process to obtain nylon sheets. Example 5

[0041] Nylon was synthesized using the production apparatus of Example 1, and the steps were as follows: 1) A 50% (wt%) salt solution generated by equimolar amounts of alicyclic diamine and sebacic acid is sent to the primary concentration vessel via pipeline, with a single input of 4t. Under the heating and evaporation of the production steam in the secondary concentration vessel, the nylon salt is concentrated to 60% (wt%). The concentrated nylon salt then flows into the secondary concentration vessel by gravity.

[0042] 2) In the secondary concentration vessel, under the heating and evaporation of saturated steam, the PA6I / 6T salt solution is concentrated to 75% (wt%) in about 50 minutes. The concentrated nylon salt then flows into the polymerization vessel by gravity.

[0043] 3) Dimethyl silicone oil (concentration of 20wt%, 0.003% of nylon chip product) is added to the polymerization reactor as an antifoaming agent through the second additive inlet. The secondary concentrated salt solution enters the polymerization reactor. The polymerization temperature and pressure are increased until the pressure inside the reactor reaches about 1.9 MPaG. The pressure is maintained at 1.9 MPaG. The polymerization temperature is slowly increased to about 250-265℃. The pressure is maintained for 90 minutes. The pressure inside the polymerization reactor is gradually reduced to atmospheric pressure. The temperature inside the polymerization reactor is controlled at 280-290℃. At 280-290℃, the pressure inside the reactor is reduced to 0.06 MPaA. The polymerization continues for 20 minutes.

[0044] 4) Adjust the nitrogen pipeline pressure on the polymerization reactor to 0.8 MPaG, move the mobile platform to the switching space, connect the inlet of the melt booster pump to the outlet of the polymerization reactor, and pressurize, filter, form, slice, cool and crystallize, separate water and dry the melt material according to the conventional slicing process to obtain nylon sheets.

Claims

1. A production apparatus for multi-configuration nylon, characterized in that: The system comprises a polymerization system (1), a pelletizing system (2), The polymerization system (1) comprises a first concentration kettle (3), a second concentration kettle (4), and a polymerization kettle (5). The first concentration kettle (2) is connected with a source of nylon salt aqueous solution. The first concentration kettle (3) is connected with the second concentration kettle (4). The second concentration kettle (4) is connected with the polymerization kettle (5). The top of the polymerization kettle (5) is provided with a pressurizing pipe (6) connected with a high-pressure gas source and a gas phase outlet (7) connected with a negative pressure source. The pelletizing system (2) comprises a pull strip pelletizing mechanism (8) and a die face pelletizing mechanism (9). The pull strip pelletizing mechanism (8) comprises a strip casting head (10) and a pelletizer (11). The outlet of the strip casting head (10) is connected with the pelletizer (11) through a cooling tank (12). The die face pelletizing mechanism (9) comprises a melt booster pump (13) and a cutter (14). The outlet of the melt booster pump (13) is connected with the cutter (14) through a die head (15). The cutter (14) is connected with a slice cooling crystallizer (16). The inlet of the strip casting head (10) or the inlet of the melt booster pump (13) is detachably connected with the outlet of the polymerization kettle.

2. The apparatus for producing multi-state nylon according to claim 1, wherein: The second concentration kettle (4) is located below the first concentration kettle (3) and above the polymerization kettle (5). The first concentration kettle (3), the second concentration kettle (4), and the polymerization kettle (5) are all provided with heat exchangers. The top of the second concentration kettle (4) is provided with a first additive inlet (17), and the top of the polymerization kettle (5) is provided with a second additive inlet (18). The top of the first concentration kettle (3) is provided with a first concentration kettle gas phase outlet (19) connected with a condenser (20). The top of the second concentration kettle (4) is provided with a second concentration kettle gas phase outlet (21) for providing heat to the heat exchanger of the first concentration kettle (3).

3. The apparatus for producing multi-state nylon according to claim 1, wherein: The polymerization kettle gas phase outlet (7) is connected with a negative pressure source through the shell side of a tail gas heat exchanger (22). The top of the shell side of the tail gas heat exchanger (22) is provided with a sprayer (23), and the bottom of the shell side of the tail gas heat exchanger (22) is provided with a settling tank (24). The settling tank (24) is connected with a polymerization washing pump (25) and a washing water cooler (26) to provide spraying water to the sprayer (23).

4. The apparatus for producing multi-state nylon according to claim 1, wherein: The bottom of the shell side of the tail gas heat exchanger (22) is provided with a liquid seal pipe (27) extending downward. The liquid seal pipe (27) extends below the liquid level of the settling tank (24), and the liquid seal height is greater than or equal to 10 m.

5. The apparatus for producing multi-state nylon according to claim 1, wherein: The cooling tank (12) comprises first and second water spraying cooling tanks (121, 122) with the same extension direction. The strip casting head (10) is located on one side of the outlet of the polymerization kettle. The outlet of the strip casting head (10) is connected with the first and second water spraying cooling tanks (121, 122) to supply the pelletizer (11).

6. The apparatus for producing multi-state nylon according to claim 5, wherein: The first water spraying cooling tank (121) moves vertically along the extension direction, and the second water spraying cooling tank (122) is vertically staggered, so that a switching space (28) is formed between the polymerization kettle (5) and the second water spraying cooling tank (122), and the melt booster pump (13), the die head (15) and the cutter (14) are arranged on the moving platform and can enter and exit the switching space (28).

7. The apparatus for producing multi-state nylon according to any one of claims 1 to 6, wherein: The water distributor (29) and the dehydration dryer (30) are further included, and the discharge outlets of the pelletizer (11) and the flake cooling crystallizer (16) supply the dehydration dryer (30) through the water distributor (29).

8. Process for the production of nylon using a plant according to any one of claims 1-7, characterized in that, The method comprises the following steps: 1) a nylon salt aqueous solution is concentrated in a first concentration kettle and a second concentration kettle in sequence, and sodium hypophosphite is added through a first additive inlet to obtain a nylon salt slurry, 2) the nylon salt slurry is sent to a polymerization kettle, the pressure of the polymerization kettle is controlled to 1.6-1.9 Mpa, and the temperature is controlled to 250-270℃, the polymerization reaction is performed for 30-90 min, the pressure is controlled to normal pressure, the temperature is adjusted to 245-290℃, and then the pressure is controlled to 0.05-0.06 Mpa, and the polymerization reaction is performed for 10-30 min to obtain a melt material; 3) according to the material characteristics of the melt material, a casting head or a feeding inlet of a melt booster pump is connected to a discharge outlet of the polymerization kettle, and the polymerization kettle is pressurized to 0.6-0.9 Mpa through a pressurizing pipe, and the melt material is discharged to be pelletized or flaked.

9. The method of claim 8, wherein, In step 1), the concentration multiple of the first concentration kettle is 1.14-1.30, the concentration multiple of the second concentration kettle is 1.15-1.35, sodium hypophosphite is added in the form of an aqueous solution, the concentration is 10 wt%, and the addition amount of the sodium hypophosphite aqueous solution is 0.03% of the mass of the nylon pellet or flake product.

10. The method of claim 8, wherein, In step 2), caprolactam is added to the polymerization kettle, and the addition amount is 2-10% of the mass of the nylon pellet or flake product.

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