Nylon 66 continuous salifying device

Abstract

The utility model belongs to the technical field of chemical equipment, and particularly relates to a nylon 66 continuous salifying device. Comprising a first-stage salifying kettle, a second-stage salifying kettle, a refined salt storage tank and a concentrator which are sequentially connected, a feed port of the first-stage salifying kettle is connected with a pure water pipeline, a hexamethylenediamine pipeline and an adipic acid pipeline, and a feed port of the second-stage salifying kettle is also connected with a hexamethylenediamine pipeline; the first-stage salt forming kettle and the second-stage salt forming kettle are both connected with an outer circulation pipeline; a waste liquid outlet of the concentrator is sequentially connected with a condenser and a concentrated water storage tank through pipelines; an outlet of the concentrated water storage tank is connected to a pure water pipeline through a pipeline; a control system is further included. Through a continuous production process and full-system automatic control, human deviation is reduced, and the index stability of the salt solution is improved; meanwhile, compared with traditional intermittent production, the production capacity and efficiency are improved, the color value of the product is improved through the full-closed design, the risk that the UV value exceeds the standard is reduced, resource recycling is achieved through recycling of concentrated water, and the production cost is overall reduced.

Description

Technical Field

[0001] This utility model belongs to the field of chemical equipment technology, specifically relating to a continuous salt-forming device for nylon 66. Background Technology

[0002] Nylon 66 is a major category of nylon products. Its synthetic raw materials are adipic acid and hexamethylenediamine. The process is as follows: hexamethylenediamine and adipic acid react in an equimolar ratio to first form a low-concentration nylon 66 salt solution. Then, through concentration and polymerization processes, water in the system is continuously removed to form a large molecular molten polymer. Subsequently, it goes through processes such as melt casting, cooling, pelletizing, drying, sieving, and packaging to finally obtain the finished product.

[0003] Currently, the salt formation process of nylon 66 is mainly carried out using an intermittent method. This process employs a kettle-type agitator for single-pot batch operation, requiring manual weighing before feeding. After the material is uniformly mixed and sampled for testing to ensure compliance with indicators, it is then discharged into a storage tank for later use. This method has several problems: manual operation is not only labor-intensive but also prone to human error, affecting the stability of product indicators; production efficiency is low, far less than the capacity of continuous salt formation processes; the feeding process cannot be completely sealed, allowing air to easily enter the system, leading to yellowing of the material and excessive UV values; manual sampling suffers from poor data timeliness and makes material recovery difficult; furthermore, fluctuations in salt solution indicators between batches further affect the final product quality.

[0004] Therefore, developing an efficient, stable, and automated continuous salt-forming device is of great significance for improving the production level of nylon 66. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a continuous salt-forming device for nylon 66. Through continuous production process and fully automated system control, it replaces the traditional intermittent manual operation, greatly reduces human error, and improves the stability of salt solution indicators. At the same time, compared with the traditional intermittent production of the same volume reactor, it significantly improves production capacity and efficiency. The fully enclosed design improves the product color value and reduces the risk of UV value exceeding the standard. In addition, the reuse of concentrated water realizes resource recycling and reduces the overall production cost.

[0006] This utility model is achieved using the following technical solution:

[0007] The nylon 66 continuous salt-forming device includes a primary salt-forming kettle, a secondary salt-forming kettle, a refined salt storage tank, and a concentrator connected in sequence. The inlet of the primary salt-forming kettle is connected to a pure water pipeline, a hexamethylenediamine pipeline, and an adipic acid pipeline, respectively. The inlet of the secondary salt-forming kettle is also connected to a hexamethylenediamine pipeline. Both the primary and secondary salt-forming kettles are connected to external circulation pipelines. The concentrated liquid outlet of the concentrator is connected to the polymerization process unit via a pipeline. The waste liquid outlet of the concentrator is connected to a condenser and a concentrated water storage tank in sequence via a pipeline. The outlet of the concentrated water storage tank is connected to a pure water pipeline via a pipeline, and the outlet of the pipeline connected to the pure water pipeline is located before the inlet of the first flow meter on the pure water pipeline. The device also includes a control system.

[0008] A second flow meter is installed on the pipeline from the hexamethylenediamine pipeline to the feed inlet of the primary salt-forming reactor, a third flow meter is installed on the pipeline from the hexamethylenediamine pipeline to the feed inlet of the secondary salt-forming reactor, and a fourth flow meter is installed on the adipic acid pipeline. The first, second, third, and fourth flow meters are electrically connected to the control system.

[0009] The outlet pipeline of the primary salt-forming reactor is equipped with a first circulation pump. The outlet of the first circulation pump is connected to two paths. One path is connected to the external circulation pipeline of the primary salt-forming reactor through a pipeline equipped with a first control valve, and the other path is connected to the feed inlet of the secondary salt-forming reactor through a pipeline equipped with a second control valve. The external circulation pipeline of the primary salt-forming reactor is also equipped with a first pH meter. The first control valve, the second control valve, and the first pH meter are electrically connected to the control system.

[0010] The outlet pipeline of the secondary salt-forming reactor is equipped with a second circulation pump, and the outlet pipeline of the second circulation pump is equipped with an online concentration meter. The outlet of the online concentration meter is connected in two ways: one way is connected to the external circulation pipeline of the secondary salt-forming reactor through a pipeline equipped with a third control valve, and the other way is connected to the feed inlet of the refined salt storage tank through a pipeline equipped with a fourth control valve. The external circulation pipeline of the secondary salt-forming reactor is also equipped with a second pH meter. The online concentration meter, the third control valve, the fourth control valve, and the second pH meter are electrically connected to the control system.

[0011] A first delivery pump is installed on the pipeline between the refined salt storage tank and the concentrator, a second delivery pump is installed on the pipeline between the concentrator and the condenser, and a third delivery pump is installed on the pipeline between the concentrated water storage tank and the pure water pipeline.

[0012] The concentrated water storage tank is equipped with a level gauge, which is electrically connected to the control system.

[0013] A fifth control valve is installed on the pipeline between the concentrated water storage tank and the pure water pipeline, and a sixth control valve is installed at the inlet of the pure water pipeline. The fifth and sixth control valves are electrically connected to the control system.

[0014] The working principle of the nylon 66 continuous salt-forming device is as follows:

[0015] Hexamethylenediamine, adipic acid, and pure water are metered by the second, fourth, and first flow meters, respectively, and then enter the primary salt-forming reactor in proportion. Simultaneously, the recycled concentrated water (containing dissolved hexamethylenediamine) in the concentrated water storage tank can enter the pure water pipeline (located before the inlet of the first flow meter) via the third transfer pump and the fifth control valve, replacing part of the pure water as raw material. Inside the primary salt-forming reactor, the materials are thoroughly mixed through stirring and the external circulation pipeline. The first pH meter on the external circulation pipeline monitors the solution pH in real time. The control system interlocks and adjusts the feed ratio of the hexamethylenediamine pipeline and the adipic acid pipeline based on the monitoring values ​​to stabilize the pH at 6-7.

[0016] Once the pH in the primary salt-forming reactor reaches the target level, the control system closes the first control valve and opens the second control valve, allowing the material to be transported to the secondary salt-forming reactor via the first circulation pump. The secondary salt-forming reactor is replenished with hexamethylenediamine via a separate hexamethylenediamine pipeline, with the replenishment amount monitored by a third flow meter. Under the action of stirring and external circulation, the second pH meter on the external circulation pipeline monitors the pH in real time, and the control system precisely adjusts the replenishment amount accordingly, raising the pH to 7.3-7.6. Simultaneously, the online concentration meter at the outlet of the second circulation pump monitors the material concentration. Once the target concentration (50-55%) is reached, the control system closes the third control valve and opens the fourth control valve, allowing the material to enter the refined salt storage tank for buffering.

[0017] The material in the refined salt storage tank is pumped into the concentrator via the first transfer pump. After being concentrated to 80-85%, the concentrate is then pumped into the polymerization unit through the concentrate outlet. The wastewater containing hexamethylenediamine generated during concentration is pumped into the condenser via the waste liquid outlet and the second transfer pump. After condensation, it is stored in the concentrate water storage tank. During the concentrate water reuse process, the control system monitors the concentrate water storage tank level through a level gauge: when the level is higher than the threshold, the sixth control valve is closed and the fifth control valve is opened, prioritizing the reuse of concentrate water; when the level is lower than the threshold, the fifth control valve is closed and the sixth control valve is opened, and pure water is added through the pure water pipeline.

[0018] Throughout the process, the control system processes the signals from various flow meters, control valves, pH meters, concentration meters, and level gauges in a coordinated manner to achieve fully automated operation.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0020] The nylon 66 continuous salt-forming device described in this invention achieves efficient and stable operation of the salt-forming process by constructing a continuous production process and combining it with full-system automated control. This device completely replaces the traditional batch method's manual operation mode, significantly reducing deviations caused by human factors, and significantly improving the stability of salt solution indicators, providing a high-quality raw material guarantee for subsequent polymerization processes. Simultaneously, compared to the traditional batch production in a reactor of the same volume, the continuous production mode significantly increases capacity and optimizes production efficiency. The fully enclosed process design effectively prevents air from entering, improving product color value and reducing the risk of excessive UV values. Furthermore, the concentrated water reuse system achieves resource recycling, and combined with automated control, reduces labor costs, thereby lowering the overall production cost. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the nylon 66 continuous salt-forming device described in this utility model;

[0022] In the diagram: 1. Primary salt-forming kettle; 2. Secondary salt-forming kettle; 3. Refined salt storage tank; 4. Concentrator; 5. Pure water pipeline; 6. Hexamethylenediamine pipeline; 7. Adipic acid pipeline; 8. Polymerization process unit; 9. Condenser; 10. Concentrated water storage tank; 11. First flow meter; 12. Second flow meter; 13. Third flow meter; 14. Fourth flow meter; 15. First circulating pump; 16. First control valve; 17. Second control valve; 18. First pH meter; 19. Second circulating pump; 20. Online concentration meter; 21. Third control valve; 22. Fourth control valve; 23. Second pH meter; 24. First transfer pump; 25. Second transfer pump; 26. Third transfer pump; 27. Level gauge; 28. Fifth control valve; 29. ​​Sixth control valve. Detailed Implementation

[0023] To make the objectives and technical solutions of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings.

[0024] Example 1

[0025] like Figure 1As shown, the nylon 66 continuous salt-forming device includes a primary salt-forming kettle 1, a secondary salt-forming kettle 2, a refined salt storage tank 3, and a concentrator 4 connected in sequence. The inlet of the primary salt-forming kettle 1 is connected to a pure water pipeline 5, a hexamethylenediamine pipeline 6, and an adipic acid pipeline 7, respectively. The inlet of the secondary salt-forming kettle 2 is also connected to a hexamethylenediamine pipeline 6. Both the primary salt-forming kettle 1 and the secondary salt-forming kettle 2 are connected to external circulation pipelines. The concentrated liquid outlet of the concentrator 4 is connected to the polymerization process unit 8 through a pipeline. The waste liquid outlet of the concentrator 4 is connected to a condenser 9 and a concentrated water storage tank 10 in sequence through a pipeline. The outlet of the concentrated water storage tank 10 is connected to the pure water pipeline 5 through a pipeline, and the outlet of the pipeline connected to the pure water pipeline 5 is located before the inlet of the first flow meter 11 on the pure water pipeline 5. The device also includes a control system.

[0026] A second flow meter 12 is installed on the pipeline from the hexamethylenediamine pipeline 6 to the feed inlet of the primary salt-forming reactor 1, a third flow meter 13 is installed on the pipeline from the hexamethylenediamine pipeline 6 to the feed inlet of the secondary salt-forming reactor 2, and a fourth flow meter 14 is installed on the adipic acid pipeline 7. The first flow meter 11, the second flow meter 12, the third flow meter 13 and the fourth flow meter 14 are electrically connected to the control system.

[0027] The outlet pipeline of the primary salt-forming reactor 1 is equipped with a first circulation pump 15. The outlet of the first circulation pump 15 is connected to two paths. One path is connected to the external circulation pipeline of the primary salt-forming reactor 1 through a pipeline equipped with a first control valve 16, and the other path is connected to the feed inlet of the secondary salt-forming reactor 2 through a pipeline equipped with a second control valve 17. The external circulation pipeline of the primary salt-forming reactor 1 is also equipped with a first pH meter 18. The first control valve 16, the second control valve 17 and the first pH meter 18 are electrically connected to the control system.

[0028] The outlet pipeline of the secondary salt-forming reactor 2 is equipped with a second circulation pump 19, and the outlet pipeline of the second circulation pump 19 is equipped with an online concentration meter 20. The outlet of the online concentration meter 20 is connected in two ways: one way is connected to the external circulation pipeline of the secondary salt-forming reactor 2 through a pipeline equipped with a third control valve 21, and the other way is connected to the feed inlet of the refined salt storage tank 3 through a pipeline equipped with a fourth control valve 22. The external circulation pipeline of the secondary salt-forming reactor 2 is also equipped with a second pH meter 23. The online concentration meter 20, the third control valve 21, the fourth control valve 22 and the second pH meter 23 are electrically connected to the control system.

[0029] A first delivery pump 24 is installed on the pipeline between the refined salt storage tank 3 and the concentrator 4, a second delivery pump 25 is installed on the pipeline between the concentrator 4 and the condenser 9, and a third delivery pump 26 is installed on the pipeline between the concentrated water storage tank 10 and the pure water pipeline 5.

[0030] The concentrated water storage tank 10 is equipped with a level gauge 27, which is electrically connected to the control system.

[0031] A fifth control valve 28 is provided on the pipeline between the concentrated water storage tank 10 and the pure water pipeline 5, and a sixth control valve 29 is provided at the inlet of the pure water pipeline 5. The fifth control valve 28 and the sixth control valve 29 are electrically connected to the control system.

[0032] The specific steps for doing this are as follows:

[0033] Open the sixth control valve 29 of the pure water pipeline 5. Pure water enters the primary salt-forming reactor 1 after being metered by the first flow meter 11. Hexamethylenediamine is metered by the second flow meter 12, and adipic acid is metered by the fourth flow meter 14, and they enter the primary salt-forming reactor 1 simultaneously. Start the agitator and the first circulation pump 15 of the primary salt-forming reactor 1, and open the first control valve 16 to allow the materials to circulate and mix through the external circulation pipeline. The first pH meter 18 provides real-time feedback on the pH value. The control system adjusts the amount of hexamethylenediamine and adipic acid added according to the value to stabilize the pH at 6.5±0.5.

[0034] Once the pH in the primary salt-forming reactor 1 stabilizes at 6.5±0.5, close the first control valve 16 and open the second control valve 17. The material then enters the secondary salt-forming reactor 2 via the first circulation pump 15. Start the agitator and the second circulation pump 19 in the secondary salt-forming reactor 2, and open the third control valve 21 to circulate the material through the external circulation pipeline. Simultaneously, add hexamethylenediamine to the secondary salt-forming reactor 2 through the hexamethylenediamine pipeline 6. Monitor the amount added using the third flow meter 13 and the pH value using the second pH meter 23, precisely adjusting the pH to 7.45±0.15.

[0035] When the second pH meter 23 in the secondary salt-forming reactor 2 shows a pH of 7.45±0.15, and the online concentration meter 20 monitors a concentration of 55%, the third control valve 21 is closed and the fourth control valve 22 is opened, and the material enters the refined salt storage tank 3 for buffering via the second circulation pump 19.

[0036] Start the first transfer pump 24 to send the material in the refined salt storage tank 3 into the concentrator 4. After concentrating to 85%, the concentrated liquid enters the polymerization process unit 8 through the concentrated liquid outlet. The wastewater generated by the concentration is sent to the condenser 9 through the second transfer pump 25. After condensation, it enters the concentrated water storage tank 10.

[0037] The liquid level in the concentrated water storage tank 10 is monitored by the liquid level gauge 27. When the liquid level is higher than the threshold, the sixth control valve 29 is closed, the fifth control valve 28 and the third transfer pump 26 are opened, and the concentrated water enters the primary salt-forming kettle 1 for reuse through the pure water pipeline 5. When the liquid level is lower than the threshold, the fifth control valve 28 and the third transfer pump 26 are closed, the sixth control valve 29 is opened, and pure water is added through the pure water pipeline 5.

[0038] By repeating the above steps, continuous salt production is achieved through the coordinated control of various flow meters, control valves, and monitoring instruments by the control system.

Claims

1. A continuous salt-forming apparatus for nylon 66, characterized in that, The system includes a primary salt-forming kettle (1), a secondary salt-forming kettle (2), a refined salt storage tank (3), and a concentrator (4) connected in sequence. The inlet of the primary salt-forming kettle (1) is connected to a pure water pipeline (5), a hexamethylenediamine pipeline (6), and an adipic acid pipeline (7), respectively. The inlet of the secondary salt-forming kettle (2) is also connected to a hexamethylenediamine pipeline (6). Both the primary salt-forming kettle (1) and the secondary salt-forming kettle (2) are connected to an external circulation pipeline. The concentrated liquid outlet of the concentrator (4) is connected to the polymerization process unit (8) through a pipeline. The waste liquid outlet of the concentrator (4) is connected to the condenser (9) and the concentrated water storage tank (10) in sequence through a pipeline. The outlet of the concentrated water storage tank (10) is connected to the pure water pipeline (5) through a pipeline. The outlet of the pipeline connecting to the pure water pipeline (5) is located before the inlet of the first flow meter (11) on the pure water pipeline (5). The system also includes a control system.

2. The nylon 66 continuous salt-forming apparatus according to claim 1, characterized in that, A second flow meter (12) is installed on the pipeline from the hexamethylenediamine pipeline (6) to the feed inlet of the primary salt-forming reactor (1), a third flow meter (13) is installed on the pipeline from the hexamethylenediamine pipeline (6) to the feed inlet of the secondary salt-forming reactor (2), and a fourth flow meter (14) is installed on the adipic acid pipeline (7). The first flow meter (11), the second flow meter (12), the third flow meter (13) and the fourth flow meter (14) are electrically connected to the control system.

3. The nylon 66 continuous salt-forming apparatus according to claim 1, characterized in that, The outlet pipeline of the primary salt-forming reactor (1) is equipped with a first circulation pump (15). The outlet of the first circulation pump (15) is connected to two paths. One path is connected to the external circulation pipeline of the primary salt-forming reactor (1) through a pipeline equipped with a first control valve (16), and the other path is connected to the feed port of the secondary salt-forming reactor (2) through a pipeline equipped with a second control valve (17). The external circulation pipeline of the primary salt-forming reactor (1) is also equipped with a first pH meter (18). The first control valve (16), the second control valve (17) and the first pH meter (18) are electrically connected to the control system.

4. The nylon 66 continuous salt-forming apparatus according to claim 1, characterized in that, The outlet pipeline of the secondary salt-forming kettle (2) is equipped with a second circulation pump (19), and the outlet pipeline of the second circulation pump (19) is equipped with an online concentration meter (20). The outlet of the online concentration meter (20) is connected in two ways. One way is connected to the external circulation pipeline of the secondary salt-forming kettle (2) through a pipeline equipped with a third control valve (21), and the other way is connected to the feed inlet of the refined salt storage tank (3) through a pipeline equipped with a fourth control valve (22). The external circulation pipeline of the secondary salt-forming kettle (2) is also equipped with a second pH meter (23). The online concentration meter (20), the third control valve (21), the fourth control valve (22) and the second pH meter (23) are electrically connected to the control system respectively.

5. The nylon 66 continuous salt-forming apparatus according to claim 1, characterized in that, A first delivery pump (24) is installed on the pipeline between the refined salt storage tank (3) and the concentrator (4), a second delivery pump (25) is installed on the pipeline between the concentrator (4) and the condenser (9), and a third delivery pump (26) is installed on the pipeline between the concentrated water storage tank (10) and the pure water pipeline (5).

6. The nylon 66 continuous salt-forming apparatus according to claim 1, characterized in that, The concentrated water storage tank (10) is equipped with a level gauge (27), which is electrically connected to the control system.

7. The nylon 66 continuous salt-forming apparatus according to claim 1, characterized in that, A fifth control valve (28) is provided on the pipeline between the concentrated water storage tank (10) and the pure water pipeline (5), and a sixth control valve (29) is provided at the inlet of the pure water pipeline (5). The fifth control valve (28) and the sixth control valve (29) are electrically connected to the control system respectively.

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