An extraction separation system for use in a caprolactam production process

Abstract

This invention relates to the field of chemical technology, and specifically discloses an extraction and separation system for caprolactam production. The system includes a circulating working fluid tank, a crude caprolactam oil tank, a heat exchanger, a transfer pump, and an extraction device. A first feed pipe connects the outlet at the bottom of the circulating working fluid tank to the inlet at the top of the crude caprolactam oil tank. A processing structure is installed on the first feed pipe. The circulating working fluid in the tank flows sequentially through the first feed pipe to a circulating working fluid precision filter, a static mixer, a circulating working fluid buffer and pressure stabilizing tank, and a circulating working fluid defoaming and fine filter, completing impurity filtration, homogenization, flow and pressure stabilization, and defoaming and fine filtration purification before being transported to the crude caprolactam oil tank for thorough mixing with the crude caprolactam oil. This solves the problems of impurities in the circulating working fluid, uneven mixing, fluctuations in transport pressure, and entrainment of air bubbles.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to an extraction and separation system for use in the production process of caprolactam. Background Technology

[0002] The caprolactam production reaction tail gas deliquescence and separation unit is a key pretreatment device in the caprolactam production process. Its core function is to separate crude caprolactam oil and other liquid impurities entrained in the reaction tail gas, providing qualified materials for subsequent extraction and refining processes.

[0003] A search of Chinese patent publication number "CN222854670U" reveals an "extraction device" that simultaneously sets up a first extraction component and a second extraction component in the same extraction device. The two sets of extraction components can perform different operations on the same material, which can significantly improve the extraction yield and shorten the extraction time, thereby improving the extraction efficiency.

[0004] Based on the above search and existing technology findings, the aforementioned patent has certain defects: In actual caprolactam production, the crude caprolactam oil after dehydration and separation of the reaction tail gas often comes from multiple feed sources, and the material composition and pH fluctuate. Directly entering the extraction unit can easily lead to unstable process parameters, affecting the extraction effect. At the same time, in caprolactam production, insufficient temperature will reduce the solubility of the material in the solvent, weakening the interphase mass transfer effect, while excessive temperature can easily cause emulsification problems, resulting in poor separation effect. The temperature control method of this device is difficult to balance the contradiction between mass transfer improvement and emulsification control. Moreover, the crude caprolactam oil after dehydration and separation of the reaction tail gas often comes from multiple feed sources, and the material composition, pH, flow rate and impurity content all fluctuate significantly. In addition, the material often contains solid impurities and bubbles. The device does not have pre-treatment structures such as pre-filtration, homogenization mixing, flow stabilization and pressure stabilization, and defoaming fine filtration. Even if the dual extraction unit has excellent efficiency, it is difficult to make up for the separation quality shortcomings caused by insufficient material pretreatment, which can easily lead to a decrease in extraction and separation accuracy. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides an extraction and separation system for caprolactam production processes, which solves the technical problem of inconvenient use of existing equipment.

[0007] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: An extraction and separation system for caprolactam production includes a circulating working liquid tank, a crude caprolactam oil tank, a heat exchanger, a transfer pump, and an extraction device. The circulating working liquid tank is used to supply circulating working liquid to the crude caprolactam oil tank to mix the crude caprolactam oil, adjust its pH value, and optimize the extraction effect, while reducing equipment operation fluctuations caused by multiple feed sources.

[0008] Preferably, a first conveying pipe is connected between the outlet at the bottom of the circulating working fluid tank and the inlet at the top of the crude caprolactam oil tank. The first conveying pipe is used to stably convey the circulating working fluid, so as to mix the crude caprolactam oil with the circulating working fluid.

[0009] Preferably, a second feed pipe is connected between the outlet at the bottom of the crude caprolactam oil tank and the inlet at the top of the heat exchanger; a third feed pipe is connected between the outlet at the bottom of the heat exchanger and one of the inlets at the top of the delivery pump; the second feed pipe is used to transport the crude caprolactam oil; the heat exchanger is used to regulate the temperature of the crude caprolactam oil to improve the solubility of the material in the solvent; and a fourth feed pipe is connected between the outlet of the delivery pump and the inlet at the top of the extraction device.

[0010] Preferably, the second feed pipe is equipped with a first temperature control valve, which is used to control the subsequent conveying direction of the crude caprolactam oil flowing through the heat exchanger to regulate the material temperature. A branch pipe is connected between the second feed pipe and one of the inlets at the top of the conveying pump. The branch pipe is used to allow the crude caprolactam oil to be conveyed directly to the conveying pump across the heat exchanger to reduce conveying resistance and equipment wear. The first temperature control valve is located on the second feed pipe section between the branch pipe and the heat exchanger. A second temperature control valve is provided on the branch pipe near the outlet of the second feed pipe. The first temperature control valve and the second temperature control valve work together and pass through the branch pipe to switch the conveying path of the crude caprolactam oil.

[0011] Preferably, the first feed pipe is equipped with a processing structure, which can realize impurity filtration, homogenization mixing, flow and pressure stabilization, and defoaming and fine filtration purification of the circulating working fluid. The processing structure includes a circulating working fluid precision filter, a static mixer, a circulating working fluid buffer and pressure stabilizing tank, and a circulating working fluid defoaming and fine filter. The outlet of the circulating working fluid tank and the inlet of the circulating working fluid precision filter are connected through the first feed pipe. The outlet of the circulating working fluid precision filter and the inlet of the static mixer are connected through the first feed pipe. The outlet of the static mixer and the inlet of the circulating working fluid buffer and pressure stabilizing tank are connected through the first feed pipe. The outlet of the circulating working fluid buffer and pressure stabilizing tank and the inlet of the circulating working fluid defoaming and fine filter are connected through the first feed pipe. The outlet of the circulating working fluid defoaming and fine filter and the inlet of the crude caprolactam oil tank are connected through the first feed pipe.

[0012] Preferably, a pipe filter is installed on the second feed pipe. The pipe filter can filter solid impurities in the crude caprolactam oil, avoid pipe blockage, and protect the downstream heat exchanger and delivery pump for stable operation. The outlet of the crude caprolactam oil tank is connected to the inlet of the pipe filter through the second feed pipe.

[0013] Preferably, the fourth feed pipe is equipped with a pre-extraction demulsifier, which can break the emulsification tendency of the material and prevent the extract from overflowing. The outlet of the conveying pump is connected to the inlet of the pre-extraction demulsifier through the fourth feed pipe, and the outlet of the pre-extraction demulsifier is connected to the inlet of the extraction device through the fourth feed pipe.

[0014] Preferably, the extraction device is provided with an outlet pipe and an outlet clarifier at the outlet end. The outlet pipe is fixedly connected between the outlet end of the extraction device and the inlet end of the outlet clarifier. The outlet clarifier can perform static phase separation on the extracted material, improve the material separation purity, and reduce the load on subsequent processes.

[0015] (III) Beneficial Effects Firstly, the circulating working fluid in the circulating working fluid tank is stably transported to the crude caprolactam oil tank through the first feed pipe, where it is fully mixed with the crude caprolactam oil in the tank. The alkalinity of the circulating working fluid is used to adjust the pH value of the crude caprolactam oil, while reducing equipment operation fluctuations caused by multiple feed sources. This can achieve the beneficial effects of improving subsequent extraction and ensuring stable operation of the unit, avoiding process fluctuation problems caused by multiple feeds. Secondly, the mixed crude caprolactam oil is transported through the second feed pipe. When the material temperature does not meet the process requirements, the first temperature control valve is opened and the second temperature control valve is closed. After the material temperature is regulated by the heat exchanger, it is transported to the delivery pump through the third feed pipe, which improves the solubility of the material in the solvent. This can achieve the beneficial effect of optimizing the extraction effect, solve the problem of low solubility and poor extraction and separation quality caused by insufficient material temperature, and meet the separation quality requirements under high-load production. Thirdly, by coordinating the operation of the first and second temperature control valves, when the material temperature is suitable for the process requirements, the first temperature control valve is closed and the second temperature control valve is opened, so that the material is directly transported to the conveying pump through the branch pipe. This can reduce the discharge resistance of the conveying pump, avoid the ineffective operation of the heat exchanger, reduce equipment wear and energy consumption, and reduce the load on subsequent processes such as benzene distillation and back extraction. Fourthly: The circulating working fluid in the circulating working fluid tank flows through the first conveying pipe sequentially through the circulating working fluid precision filter, static mixer, circulating working fluid buffer and pressure stabilizing tank, and circulating working fluid defoaming fine filter, completing impurity filtration, homogenization mixing, flow stabilization and pressure stabilization, and defoaming fine filtration purification before being conveyed to the crude caprolactam oil tank for thorough mixing with the crude caprolactam oil. This solves the problems of impurities, uneven mixing, conveying pressure fluctuations, and air bubble entrainment in the circulating working fluid, ensuring stable conveying of the circulating working fluid, improving the mixing uniformity of the crude caprolactam oil, and providing stable and reliable material conditions for subsequent extraction processes. Fifthly: After the mixed crude caprolactam oil flows out of the crude caprolactam oil tank, it is transported to the pipe filter through the second conveying pipe to complete the filtration of solid impurities. This avoids the blockage of the second conveying pipe caused by solid impurities, as well as the wear and jamming of the heat exchanger and conveying pump. It effectively protects the stable operation of downstream equipment, extends the service life of the equipment, and ensures the continuous and smooth material conveying process. Sixth: The material is transported to the pre-extraction demulsifier via the fourth feed pipe through the delivery pump to break the emulsification tendency and avoid flooding of the extract liquid. After pretreatment, it is sent to the extraction device to complete the extraction and separation. In addition, the rotation speed of the extraction device is increased and the amount of solvent benzene is reduced to improve the solubility of the material. This avoids flooding and incomplete emulsification separation during the extraction process, improves the extraction mass transfer efficiency and separation effect, reduces the amount of solvent benzene used, and optimizes the overall extraction process. Seventh: After extraction, the material is transported through the discharge pipe at the discharge end of the extraction device to the discharge clarifier for static phase separation, thereby achieving further deep purification of the extracted material, effectively improving the purity of material separation, reducing the processing load of subsequent processes, and improving the overall production process efficiency and final product quality. Attached Figure Description

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0017] Figure 1 This is a planar structural diagram of the present invention.

[0018] Legend: 11. Circulating working fluid tank; 12. Crude caprolactam oil tank; 13. Heat exchanger; 14. Transfer pump; 15. Extraction device; 16. First feed pipe; 17. Second feed pipe; 18. Third feed pipe; 19. Fourth feed pipe; 21. First temperature control valve; 22. Branch pipe; 23. Second temperature control valve; 24. Circulating working fluid precision filter; 25. Static mixer; 26. Buffer and pressure stabilizing tank; 27. Defoaming fine filter; 28. Pipe filter; 29. ​​Pre-extraction demulsifier; 31. Discharge pipe; 32. Discharge clarifier and separator. Detailed Implementation

[0019] This application provides an extraction and separation system for caprolactam production, effectively solving the technical problem of inconvenient operation of existing equipment. The system uses a circulating working fluid tank to stably transport the circulating working fluid to the crude caprolactam oil tank via a first feed pipe, where it is thoroughly mixed with the crude caprolactam oil. The alkalinity of the circulating working fluid is used to adjust the pH value of the crude caprolactam oil, while simultaneously reducing equipment operation fluctuations caused by multiple feed sources. This achieves the beneficial effects of improving subsequent extraction and ensuring stable operation of the equipment, avoiding process fluctuations caused by multiple feeds. The mixed crude caprolactam oil is transported via a second feed pipe. When the material temperature does not meet the process requirements, the first temperature control valve is opened and the second temperature control valve is closed. The control valve allows the material to be transported to the transfer pump through the third feed pipe after the temperature of the heat exchanger is regulated. This increases the solubility of the material in the solvent, thereby optimizing the extraction effect and solving the problems of low solubility and poor extraction and separation quality caused by insufficient material temperature. It meets the separation quality requirements under high-load production. Furthermore, through the coordinated action of the first and second temperature control valves, when the material temperature is suitable for the process requirements, the first temperature control valve is closed and the second temperature control valve is opened, allowing the material to be directly transported to the transfer pump through the branch pipe. This reduces the discharge resistance of the transfer pump, avoids ineffective operation of the heat exchanger, reduces equipment wear and energy consumption, and reduces the load on subsequent processes such as benzene distillation and back-extraction.

[0020] Example like Figure 1 As shown, the technical solution in this application embodiment effectively solves the technical problem of inconvenience in using existing devices. The overall idea is as follows: To address the problems existing in the prior art, the present invention provides an extraction and separation system for caprolactam production process, including a circulating working liquid tank 11, a crude caprolactam oil tank 12, a heat exchanger 13, a transfer pump 14, and an extraction device 15. The circulating working liquid tank 11 is used to deliver circulating working liquid to the crude caprolactam oil tank 12 to mix the crude caprolactam oil, adjust its pH value, and optimize the extraction effect, while reducing equipment operation fluctuations caused by multiple feed sources.

[0021] A first conveying pipe 16 is connected between the outlet at the bottom of the circulating working fluid tank 11 and the inlet at the top of the crude caprolactam oil tank 12. The first conveying pipe 16 is used to stably convey the circulating working fluid, so as to mix the crude caprolactam oil with the circulating working fluid. The circulating working fluid in the circulating working fluid tank 11 is stably transported to the crude caprolactam oil tank 12 through the first feed pipe 16, where it is fully mixed with the crude caprolactam oil in the tank. The alkalinity of the circulating working fluid is used to adjust the pH value of the crude caprolactam oil, while reducing equipment operation fluctuations caused by multiple feed sources. This can achieve the beneficial effects of improving subsequent extraction and ensuring stable operation of the unit, avoiding process fluctuation problems caused by multiple feeds.

[0022] A second feed pipe 17 is connected between the discharge port at the bottom of the crude caprolactam oil tank 12 and the inlet at the top of the heat exchanger 13. A third feed pipe 18 is connected between the discharge port at the bottom of the heat exchanger 13 and one of the inlets at the top of the transfer pump 14. The second feed pipe 17 is used to transport crude caprolactam oil. The heat exchanger 13 is used to regulate the temperature of the crude caprolactam oil to improve the solubility of the material in the solvent. A fourth feed pipe 19 is connected between the discharge port of the transfer pump 14 and the inlet at the top of the extraction device 15. The mixed crude caprolactam oil is transported through the second feed pipe 17. When the material temperature does not meet the process requirements, the first temperature control valve 21 is opened and the second temperature control valve 23 is closed. After the material temperature is regulated by the heat exchanger 13, it is transported to the transfer pump 14 through the third feed pipe 18, which improves the solubility of the material in the solvent. This can achieve the beneficial effect of optimizing the extraction effect, solve the problem of low solubility and poor extraction and separation quality caused by insufficient material temperature, and meet the separation quality requirements under high-load production.

[0023] The second feed pipe 17 is equipped with a first temperature control valve 21. The first temperature control valve 21 is used to control the subsequent conveying direction of the crude caprolactam oil flowing through the heat exchanger 13 in order to regulate the material temperature. A branch pipe 22 is connected between the second feed pipe 17 and one of the feed ports at the top of the conveying pump 14. The branch pipe 22 is used to allow the crude caprolactam oil to be conveyed directly to the conveying pump 14 across the heat exchanger 13 in order to reduce conveying resistance and equipment wear. The first temperature control valve 21 is located on the section of the second feed pipe 17 between the branch pipe 22 and the heat exchanger 13. A second temperature control valve 23 is provided on the branch pipe 22 near the port of the second feed pipe 17. The first temperature control valve 21 and the second temperature control valve 23 work together and pass through the branch pipe 22 to switch the conveying path of the crude caprolactam oil. By coordinating the operation of the first temperature control valve 21 and the second temperature control valve 23, when the material temperature is suitable for the process requirements, the first temperature control valve 21 is closed and the second temperature control valve 23 is opened, so that the material is directly transported to the conveying pump 14 through the branch pipe 22. This can reduce the discharge resistance of the conveying pump 14 and avoid the ineffective operation of the heat exchanger 13, thereby reducing equipment wear and energy consumption, and reducing the load on subsequent processes such as benzene distillation and back extraction.

[0024] The first feed pipe 16 is equipped with a processing structure that can filter impurities, homogenize, stabilize flow and pressure, and defoam and finely filter the circulating working fluid. The processing structure includes a circulating working fluid precision filter 24, a static mixer 25, a circulating working fluid buffer and pressure stabilizing tank 26, and a circulating working fluid defoaming and fine filter 27. The outlet of the circulating working fluid tank 11 and the inlet of the circulating working fluid precision filter 24 are connected via the first feed pipe 16. The feed inlet is connected to the feed inlet of the static mixer 25 via a first feed pipe 16. The discharge outlet of the static mixer 25 is connected to the feed inlet of the circulating working fluid buffer and pressure stabilizing tank 26 via a first feed pipe 16. The discharge outlet of the circulating working fluid buffer and pressure stabilizing tank 26 is connected to the feed inlet of the circulating working fluid defoaming and fine filter 27 via a first feed pipe 16. The discharge outlet of the circulating working fluid defoaming and fine filter 27 is connected to the feed inlet of the crude caprolactam oil tank 12 via a first feed pipe 16. The circulating working fluid in the circulating working fluid tank 11 flows through the first feed pipe 16 sequentially through the circulating working fluid precision filter 24, static mixer 25, circulating working fluid buffer and pressure stabilizing tank 26, and circulating working fluid defoaming fine filter 27, completing impurity filtration, homogenization mixing, flow stabilization and pressure stabilization, and defoaming fine filtration purification before being transported to the crude caprolactam oil tank 12 to be fully mixed with the crude caprolactam oil. This solves the problems of impurities, uneven mixing, pressure fluctuations, and air bubble entrainment in the circulating working fluid, ensuring stable circulating working fluid delivery, improving the mixing uniformity of the crude caprolactam oil, and providing stable and reliable material conditions for subsequent extraction processes.

[0025] The second feed pipe 17 is equipped with a feed filter 28, which can filter solid impurities in crude caprolactam oil, prevent pipeline blockage and protect the subsequent heat exchanger 13 and delivery pump 14 to operate stably. The outlet of crude caprolactam oil tank 12 is connected to the inlet of feed filter 28 through the second feed pipe 17. After the mixed crude caprolactam oil flows out of the crude caprolactam oil tank 12, it is transported through the second conveying pipe 17 to the pipe material filter 28 to complete the filtration of solid impurities. This avoids the problem of solid impurities causing blockage of the second conveying pipe 17 and wear and jamming of the heat exchanger 13 and the conveying pump 14. It effectively protects the stable operation of downstream equipment, extends the service life of equipment, and ensures the continuous and smooth material conveying process.

[0026] The fourth feed pipe 19 is equipped with a pre-extraction demulsifier 29, which can break the emulsification tendency of the material and prevent the extract liquid from overflowing. The discharge port of the conveying pump 14 is connected to the inlet of the pre-extraction demulsifier 29 through the fourth feed pipe 19, and the discharge port of the pre-extraction demulsifier 29 is connected to the inlet of the extraction device 15 through the fourth feed pipe 19. The material is conveyed by the conveying pump 14 through the fourth conveying pipe 19 to the pre-extraction demulsifier 29 for pretreatment to break emulsification tendency and avoid flooding of the extract liquid. After pretreatment, it is sent to the extraction device 15 to complete the extraction and separation. In addition, the rotation speed of the extraction device 15 is increased and the amount of solvent benzene is reduced to improve the solubility of the material, thereby avoiding flooding and incomplete emulsification separation during the extraction process, improving the extraction mass transfer efficiency and separation effect, reducing the amount of solvent benzene used, and optimizing the overall extraction process.

[0027] The discharge end of the extraction device 15 is provided with a discharge pipe 31 and a discharge clarifier 32. The discharge pipe 31 is fixedly connected between the discharge end of the extraction device 15 and the inlet end of the discharge clarifier 32. The discharge clarifier 32 can perform static phase separation on the extracted material, improve the material separation purity, and reduce the load of subsequent processes. After extraction, the material is transported through the discharge pipe 31 at the discharge end of the extraction device 15 to the discharge clarifier 32 for static phase separation, thereby achieving further deep purification of the extracted material, effectively improving the material separation purity, reducing the processing load of subsequent processes, and improving the overall production process efficiency and final product quality.

[0028] Working principle: The circulating working fluid in the circulating working fluid tank 11 flows sequentially through the first feed pipe 16, passing through the circulating working fluid precision filter 24, static mixer 25, circulating working fluid buffer and pressure stabilizing tank 26, and circulating working fluid defoaming fine filter 27. After impurity filtration, homogenization mixing, flow stabilization and pressure stabilization, and defoaming fine filtration purification, it is transported to the crude caprolactam oil tank 12, where it is fully mixed with the crude caprolactam oil. The mixed crude caprolactam oil flows out from the bottom of the crude caprolactam oil tank 12, is transported through the second feed pipe 17, and passes through the pipe material filter 28 to filter solid impurities, preventing pipeline blockage and protecting the stable operation of the subsequent heat exchanger 13 and transfer pump 14. The filtered material is flexibly switched in its conveying path through the coordinated action of the first temperature control valve 21 and the second temperature control valve 23. When the material temperature does not meet the process requirements, the first temperature control valve 21 is opened and the second temperature control valve 23 is closed. The material enters the heat exchanger 13 through the second feed pipe 17, and after temperature adjustment, it is transported to the transfer pump 14 through the third feed pipe 18. The extraction process optimizes the extraction effect by increasing the material temperature to improve the solubility of the material in the solvent. When the material temperature meets the process requirements, the first temperature control valve 21 is closed and the second temperature control valve 23 is opened. The material is directly transported to the transfer pump 14 via the branch pipe 22, which reduces the discharge resistance of the transfer pump 14 and avoids the ineffective operation of the heat exchanger 13, thus reducing equipment wear and energy consumption. The transfer pump 14 transports the material to the pre-extraction demulsifier 29 via the fourth feed pipe 19. After pretreatment to remove emulsification tendency and prevent flooding of the extract, the material is sent to the extraction device 15 for extraction and separation. At the same time, the rotation speed of the extraction device 15 can be appropriately increased and the amount of solvent benzene can be appropriately reduced, thereby increasing the solubility of the material in the solvent and improving the extraction effect. After extraction, the material is transported to the discharge clarifier 32 via the discharge pipe 31 at the discharge end of the extraction device 15. The discharge clarifier 32 performs static phase separation on the extracted material, improving the material separation purity and reducing the load on subsequent processes.

[0029] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An extraction and separation system for use in a caprolactam production process, comprising a circulating working liquid tank (11), characterized in that, It also includes a crude caprolactam oil tank (12), a heat exchanger (13), a transfer pump (14), and an extraction device (15). The circulating working fluid tank (11) is used to deliver circulating working fluid to the crude caprolactam oil tank (12) to mix the crude caprolactam oil, adjust its pH value and optimize the extraction effect, while reducing equipment operation fluctuations caused by multiple feed sources. A first conveying pipe (16) is connected between the outlet at the bottom of the circulating working liquid tank (11) and the inlet at the top of the crude caprolactam oil tank (12). The first feed pipe (16) is equipped with a processing structure, which can realize impurity filtration, homogenization mixing, flow stabilization and pressure stabilization and defoaming fine filtration purification of the circulating working fluid.

2. The extraction and separation system for caprolactam production as described in claim 1, characterized in that, The first feed pipe (16) is used to stably transport the circulating working fluid, so as to mix the crude caprolactam oil with the circulating working fluid.

3. The extraction and separation system for caprolactam production as described in claim 2, characterized in that, A second feed pipe (17) is connected between the discharge port at the bottom of the crude caprolactam oil tank (12) and the inlet at the top of the heat exchanger (13); a third feed pipe (18) is connected between the discharge port at the bottom of the heat exchanger (13) and one of the inlets at the top of the conveying pump (14). The second feed pipe (17) is used to transport crude caprolactam oil, and the heat exchanger (13) is used to regulate the temperature of the crude caprolactam oil in order to improve the solubility of the material in the solvent.

4. An extraction and separation system for caprolactam production as described in any one of claims 1-3, characterized in that, A fourth feed pipe (19) is connected between the outlet of the delivery pump (14) and the inlet at the top of the extraction device (15).

5. The extraction and separation system for caprolactam production as described in claim 3, characterized in that, The second conveying pipe (17) is provided with a first temperature control valve (21). The first temperature control valve (21) is used to control the subsequent conveying direction of the crude caprolactam oil flowing through the heat exchanger (13) in order to adjust the material temperature. A branch pipe (22) is connected between the second conveying pipe (17) and one of the feed inlets at the top of the conveying pump (14). The branch pipe (22) is used to allow crude caprolactam oil to be directly transported across the heat exchanger (13) to the transfer pump (14) in order to reduce the transport resistance and equipment wear.

6. The extraction and separation system for caprolactam production as described in claim 5, characterized in that, The first temperature control valve (21) is located on the second feed pipe (17) section between the branch pipe (22) and the heat exchanger (13). The branch pipe (22) is provided with a second temperature control valve (23) near the pipe opening of the second feed pipe (17). The first temperature control valve (21) and the second temperature control valve (23) work together and pass through the branch pipe (22) to switch the delivery path of crude caprolactam oil.

7. The extraction and separation system for caprolactam production as described in claim 1, characterized in that, The processing structure includes a circulating working fluid precision filter (24), a static mixer (25), a circulating working fluid buffer and pressure stabilizing tank (26), and a circulating working fluid defoaming and fine filter (27). The outlet of the circulating working fluid tank (11) is connected to the inlet of the circulating working fluid precision filter (24) via a first feed pipe (16), and the outlet of the circulating working fluid precision filter (24) is connected to the inlet of the static mixer (25) via the first feed pipe (16). The outlet of the static mixer (25) is connected to the inlet of the circulating working fluid buffer and pressure stabilizing tank (26) via a first conveying pipe (16). The outlet of the circulating working fluid buffer and pressure stabilizing tank (26) is connected to the inlet of the circulating working fluid defoaming and fine filter (27) via a first conveying pipe (16). The outlet of the circulating working fluid defoaming and fine filter (27) is connected to the inlet of the crude caprolactam oil tank (12) via a first conveying pipe (16).

8. The extraction and separation system for caprolactam production as described in claim 3, characterized in that, A pipe filter (28) is installed on the pipeline of the second feed pipe (17). The pipe filter (28) can filter solid impurities in crude caprolactam oil, avoid pipeline blockage and protect the subsequent heat exchanger (13) and delivery pump (14) to operate stably. The outlet of the crude caprolactam oil tank (12) is connected to the inlet of the pipe filter (28) through the second feed pipe (17).

9. The extraction and separation system for caprolactam production as described in claim 4, characterized in that, The fourth feed pipe (19) is equipped with a pre-extraction demulsifier (29). The pre-extraction demulsifier (29) can break the emulsification tendency of the material and avoid the overflow of the extract. The outlet of the conveying pump (14) is connected to the inlet of the pre-extraction demulsifier (29) through the fourth feed pipe (19). The outlet of the pre-extraction demulsifier (29) is connected to the inlet of the extraction device (15) through the fourth feed pipe (19).

10. The extraction and separation system for caprolactam production as described in claim 9, characterized in that, The extraction device (15) is provided with an outlet pipe (31) and an outlet clarifier (32) at the outlet end. The outlet pipe (31) is fixedly connected between the outlet end of the extraction device (15) and the inlet end of the outlet clarifier (32). The outlet clarifier (32) can perform static phase separation on the extracted material, improve the material separation purity, and reduce the load of subsequent processes.

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