Ammonium sulfate circulating caprolactam production device

Abstract

The utility model relates to a caprolactam production device with ammonium sulfate circulation. Comprising a cyclohexanone-oxime storage tank, the cyclohexanone-oxime storage tank is connected with a caprolactam preparation unit through a rearrangement reaction unit, and the caprolactam preparation unit is connected with an ammonium sulfate recycling unit; the ammonium sulfate recycling unit comprises multiple stages of ammonium sulfate decomposition parts which are connected in series, tail end gas phase outlets of the multiple stages of ammonium sulfate decomposition parts are connected with the nicotinic acid preparation part, and the nicotinic acid preparation part is connected with the rearrangement reaction unit; through the process design, the problem of treating the byproduct ammonium sulfate by an enterprise can be solved, the consumption of raw material liquid ammonia and sulfuric acid is reduced, the investment of assorted construction of sulfur acid making by the enterprise is reduced, the operation cost of a caprolactam production enterprise is reduced, and the profitability of the enterprise is improved; and the production load of caprolactam is insufficient.

Description

Technical Field

[0001] The utility model relates to the field of caprolactam production, in particular to a caprolactam production device with ammonium sulfate circulation. Background Art

[0002] In 2019, there were 18 major caprolactam production companies in my country, with a total production capacity exceeding 4 million tons, but actual output was less than 3 million tons. The industry's operating rate was 70%, and the industry was concentrated in the eastern coastal areas and coal-rich regions. According to statistics, my country's total caprolactam production capacity will reach 6.47 million tons / year by the end of 2023, with the industry's operating rate maintained at 70%-80%. Caprolactam is produced from cyclohexanone oxime via Beckmann rearrangement. Currently, there are two rearrangement process technologies: vapor-phase rearrangement and liquid-phase rearrangement. The liquid-phase rearrangement process is mature and stable, with a single unit producing far more capacity than the vapor-phase process. Currently, there are no vapor-phase rearrangement plants in China, and all other processes use the liquid-phase rearrangement process. However, the liquid-phase Beckmann rearrangement process uses nicotinic acid as a catalyst, requiring post-reaction ammonia neutralization treatment, resulting in a large amount of ammonium sulfate as a by-product. According to statistics, 1.5-1.6 tons of ammonium sulfate are produced per ton of caprolactam. Dealing with this by-product has become a burden on existing caprolactam plants. When inventory reaches a certain level, companies resort to load reduction or maintenance measures.

[0003] Based on this, how to solve the problem of large amounts of by-product ammonium sulfate has become a technical problem that needs to be solved urgently. Utility Model Content

[0004] In order to make up for the above deficiencies, the utility model provides a caprolactam production device with ammonium sulfate circulation to solve the technical problems existing in the prior art.

[0005] The technical solution adopted by the utility model to solve its technical problems is:

[0006] A caprolactam production device with ammonium sulfate circulation comprises a cyclohexanone oxime storage tank connected to a caprolactam preparation unit via a rearrangement reaction unit, and the caprolactam preparation unit is connected to an ammonium sulfate recycling unit; the ammonium sulfate recycling unit comprises a multi-stage ammonium sulfate decomposition section arranged in series, the terminal gas phase outlet of the multi-stage ammonium sulfate decomposition section is connected to a nicotinic acid preparation section, and the nicotinic acid preparation section is connected to the rearrangement reaction unit.

[0007] The beneficial effects of the utility model are as follows: in the utility model, the cyclohexanone oxime in the cyclohexanone oxime storage tank enters the caprolactam preparation unit through the rearrangement reaction unit to prepare caprolactam, and at the same time, the by-product ammonium sulfate enters the multi-stage ammonium sulfate decomposition unit to produce SO3 gas, and nicotinic acid, a catalyst for the rearrangement reaction, is prepared based on the SO3 gas, so as to achieve the purpose of reusing ammonium sulfate and reducing the cost of caprolactam preparation, and can solve the problem of limited caprolactam production load caused by the accumulation of a large amount of ammonium sulfate.

[0008] Preferably, the multi-stage ammonium sulfate decomposition section includes an ammonium sulfate primary decomposition device and an ammonium sulfate secondary decomposition device, the gas phase outlet of the ammonium sulfate primary decomposition device is connected to the caprolactam preparation unit through an ammonia circulation section, the liquid phase outlet of the ammonium sulfate primary decomposition device is connected to the inlet of the ammonium sulfate secondary decomposition device, the liquid phase outlet of the ammonium sulfate secondary decomposition device is connected to the circulation inlet of the ammonium sulfate primary decomposition device through a circulation pump, and the gas phase outlet of the ammonium sulfate secondary decomposition device is connected to the nicotinic acid preparation section.

[0009] Preferably, the nicotinic acid preparation unit includes a fuming sulfuric acid device, the gas phase outlet of the ammonium sulfate secondary decomposition device is connected to the fuming sulfuric acid device through a third tee, the fuming sulfuric acid device is connected to the rearrangement reaction unit through a fifth tee, and the third end of the fifth tee is connected to the nicotinic acid raw material tank; the third end of the third tee is connected to the sulfuric acid condenser through a second mixer, the inlet of the second mixer is also connected to the water vapor storage tank, and the liquid phase outlet of the sulfuric acid condenser is connected to the liquid phase inlet of the fuming sulfuric acid device through a sulfuric acid water cooler.

[0010] The gas phase outlets of the oleum device and the sulfuric acid condenser are respectively connected to the tail gas treatment device.

[0011] Preferably, the rearrangement reaction unit includes an outlet of the cyclohexanone oxime storage tank connected to the primary rearrangement reactor and the secondary rearrangement reactor respectively through a first tee, the bottom circulation outlet of the primary rearrangement reactor is connected to the circulation inlet at the top of the primary rearrangement reactor through a seventh tee, a primary circulation pump and a primary cooler, the outlet at the top of the primary rearrangement reactor is connected to the secondary rearrangement reactor, and the third end of the seventh tee is connected to the fifth tee.

[0012] Preferably, the bottom circulation outlet of the secondary rearrangement reactor is connected to the circulation inlet at the top of the secondary rearrangement reactor through a second tee, a secondary circulation pump and a secondary cooler, the third end of the second tee is connected to the outlet at the top of the primary rearrangement reactor, and the outlet at the top of the secondary rearrangement reactor is connected to the caprolactam preparation unit.

[0013] Preferably, the caprolactam preparation unit includes a first mixer connected to the upper outlet of the secondary rearrangement reactor, the inlet of the first mixer is also connected to the ammonia circulation unit, the outlet of the first mixer is connected to the inlet of the neutralization reactor, the outlet of the neutralization reactor is connected to the inlet of the ammonium sulfate separator, the upper outlet of the ammonium sulfate separator is connected to the crude caprolactam tank, and the bottom outlet of the ammonium sulfate separator is connected to the ammonium sulfate primary decomposition device through an ammonium sulfate pump.

[0014] Preferably, the bottom circulation outlet of the neutralization reactor is connected to the circulation inlet of the first mixer through a neutralization circulation pump and a neutralization cooler.

[0015] Preferably, the ammonia circulation section includes an ammonia absorption tower connected to the gas phase outlet of the primary decomposition device of ammonium sulfate, a desalted water inlet connected to the desalted water storage tank is provided at the upper part of the ammonia absorption tower, and the liquid phase outlet at the bottom of the ammonia absorption tower is connected to the inlet of the first mixer through an ammonia pump.

[0016] Preferably, a sixth tee and a first valve are sequentially provided between the ammonia water pump and the inlet of the first mixer, and the third end of the sixth tee is connected to the circulation inlet in the ammonia water absorption tower through the second valve.

[0017] According to the above scheme, a caprolactam production device with ammonium sulfate circulation is made. The rearrangement reaction unit and the caprolactam preparation unit are provided to realize the production of caprolactam. The ammonium sulfate obtained by the caprolactam neutralization and crystallization device is decomposed to obtain ammonia and SO3 gas. The ammonia is absorbed by the ammonia circulation unit and the absorbed ammonia water is reused in the first mixer. At the same time, nicotinic acid is prepared from the SO3 gas and used as a catalyst in the rearrangement reaction. The specific process is that SO3 is absorbed and condensed by steam to obtain concentrated sulfuric acid, and the concentrated sulfuric acid absorbs excess SO3 to obtain nicotinic acid. Nicotinic acid continues to react as a catalyst for the Beckmann rearrangement reaction of the caprolactam device. The utility model can solve the problem of enterprises dealing with by-product ammonium sulfate through the above process design, and reduce the consumption of raw materials liquid ammonia and sulfuric acid, reduce the investment of enterprises in the construction of supporting sulfuric acid, reduce the operating costs of caprolactam production enterprises, improve the profitability of enterprises, and solve the defect of insufficient caprolactam production load. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a structural diagram of the present utility model.

[0020] In the figure: 1. Cyclohexanone oxime storage tank; 2. First tee; 3. Primary rearrangement reactor; 4. Seventh tee; 5. Primary circulation pump; 6. Primary cooler; 7. Secondary rearrangement reactor; 8. Second tee; 9. Secondary circulation pump; 10. Secondary cooler; 11. Neutralization cooler; 12. Neutralization circulation pump; 13. First mixer; 14. Neutralization reactor; 15. Ammonium sulfate separator; 16. Ammonium sulfate pump; 17. Crude caprolactam tank; 18. Ammonium sulfate Primary decomposition device; 19. Ammonia absorption tower; 20. Desalted water storage tank; 21. Ammonia pump; 22. Sixth tee; 23. Ammonium sulfate secondary decomposition device; 24. Third tee; 25. Water vapor storage tank; 26. Second mixer; 27. Sulfuric acid water cooler; 28. Sulfuric acid condenser; 29. Oleum device; 30. First valve; 31. Tail gas treatment device; 32. Nicotinic acid raw material tank; 33. Fifth tee; 34. Circulation pump; 35. Second valve. DETAILED DESCRIPTION

[0021] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] The following is combined with Figure 1 The present application is further described in detail. The utility model is a caprolactam production device with ammonium sulfate circulation, which includes a cyclohexanone oxime storage tank 1, which is connected to a caprolactam preparation unit via a rearrangement reaction unit, and the caprolactam preparation unit is connected to an ammonium sulfate recycling unit; the ammonium sulfate recycling unit includes a multi-stage ammonium sulfate decomposition section arranged in series, the terminal gas phase outlet of the multi-stage ammonium sulfate decomposition section is connected to a nicotinic acid preparation section, and the nicotinic acid preparation section is connected to the rearrangement reaction unit. The rearrangement reactor used in the rearrangement reaction unit described in the present invention is preferably a new generation Beckmann rearrangement technology, which has the characteristics of high product purity and low steam energy consumption in the preparation of caprolactam. Furthermore, in the process of producing caprolactam, the by-product ammonium sulfate enters the multi-stage ammonium sulfate decomposition section, and the SO3 gas obtained by the decomposition of ammonium sulfate is allowed to enter the nicotinic acid preparation section for the preparation of nicotinic acid. At the same time, nicotinic acid can be used as a catalyst in the rearrangement reactor. The above process can effectively solve the problem of a large amount of ammonium sulfate that cannot be handled. At the same time, the reflux of nicotinic acid into the device can effectively save the purchase of catalysts, thereby reducing the production cost of caprolactam, and has obvious economic and social benefits.

[0023] Furthermore, the multi-stage ammonium sulfate decomposition section includes an ammonium sulfate primary decomposition device 18 and an ammonium sulfate secondary decomposition device 23. The gas phase outlet of the ammonium sulfate primary decomposition device 18 is connected to the caprolactam preparation unit through an ammonia circulation section, the liquid phase outlet of the ammonium sulfate primary decomposition device 18 is connected to the inlet of the ammonium sulfate secondary decomposition device 23, the liquid phase outlet of the ammonium sulfate secondary decomposition device 23 is connected to the circulation inlet of the ammonium sulfate primary decomposition device 18 through a circulation pump 34, and the gas phase outlet of the ammonium sulfate secondary decomposition device 23 is connected to the nicotinic acid preparation section. By setting up the ammonium sulfate primary decomposition device 18, ammonium sulfate can be decomposed into ammonia gas, which is then allowed to enter the ammonia circulation unit to be reused. By utilizing the gaseous ammonia for neutralization, the water in the raw materials can be reduced, thereby achieving the characteristic of low wastewater volume of the entire device. This not only solves the environmental protection problem of caprolactam enterprises in treating by-product ammonium sulfate, but also reduces the consumption of liquid ammonia, thereby achieving the purpose of reducing the production cost of caprolactam. The ammonium sulfate primary decomposition device 18 described in the present invention includes an ammonium sulfate primary decomposition reactor, etc., which can be directly purchased on the market, so it is not described in detail. The ammonium sulfate secondary decomposition device 23 includes an ammonium sulfate secondary decomposition reactor, etc., which can be directly purchased on the market, so it is not described in detail.

[0024] Furthermore, the nicotinic acid preparation section includes a fuming sulfuric acid device 29, the gas phase outlet of the ammonium sulfate secondary decomposition device 23 is connected to the fuming sulfuric acid device 29 through a third tee 24, the fuming sulfuric acid device 29 is connected to the rearrangement reaction unit through a fifth tee 33, and the third end of the fifth tee 33 is connected to the nicotinic acid raw material tank 32; the third end of the third tee 24 is connected to the sulfuric acid condenser 28 through a second mixer 26, the inlet of the second mixer 26 is also connected to the water vapor storage tank 25, and the liquid phase outlet of the sulfuric acid condenser 28 is connected to the liquid phase inlet of the fuming sulfuric acid device 29 through a sulfuric acid water cooler 27. The present invention utilizes the SO3 gas obtained by decomposing ammonium sulfate to enter the second mixer 26 and absorb water from the water vapor storage tank 25, and cooperates with the sulfuric acid condenser 28 to prepare concentrated sulfuric acid, and then sends the concentrated sulfuric acid to the oleum device 29 to combine with the SO3 gas to produce nicotinic acid, so as to achieve the characteristics of treating by-products and reducing costs; the oleum device 29 described in the present invention includes a nicotinic acid absorption reactor, etc., which can be directly purchased on the market and therefore will not be described in detail.

[0025] Furthermore, the gas phase outlets of the fuming sulfuric acid device 29 and the sulfuric acid condenser 28 are respectively connected to an exhaust gas treatment device 31. The exhaust gas treatment device 31 described in the present invention can be a conventional acidic exhaust gas treatment device, preferably using a hydrogen peroxide treatment process to achieve the purpose of reducing air pollution and achieving clean and efficient operation. The exhaust gas treatment device 31 described in the present invention includes an exhaust gas water scrubber, a washing liquid circulation pump, a dilute acid buffer tank, etc., which can be directly purchased on the market and are therefore not described in detail.

[0026] Furthermore, the rearrangement reaction unit includes an outlet of the cyclohexanone oxime storage tank 1 connected to the primary rearrangement reactor 3 and the secondary rearrangement reactor 7 respectively through the first tee 2, the bottom circulation outlet of the primary rearrangement reactor 3 is connected to the circulation inlet at the top of the primary rearrangement reactor 3 through the seventh tee 4, the primary circulation pump 5 and the primary cooler 6, the outlet at the top of the primary rearrangement reactor 3 is connected to the secondary rearrangement reactor 7, and the third end of the seventh tee 4 is connected to the fifth tee 33.

[0027] Furthermore, the bottom circulation outlet of the secondary rearrangement reactor 7 is connected to the circulation inlet at the top of the secondary rearrangement reactor 7 through the second tee 8, the secondary circulation pump 9 and the secondary cooler 10, the third end of the second tee 8 is connected to the outlet at the top of the primary rearrangement reactor 3, and the outlet at the top of the secondary rearrangement reactor 7 is connected to the caprolactam preparation unit.

[0028] Furthermore, the caprolactam preparation unit includes a first mixer 13 connected to the upper outlet of the secondary rearrangement reactor 7, the inlet of the first mixer 13 is also connected to the ammonia circulation part, the outlet of the first mixer 13 is connected to the inlet of the neutralization reactor 14, the outlet of the neutralization reactor 14 is connected to the inlet of the ammonium sulfate separator 15, the upper outlet of the ammonium sulfate separator 15 is connected to the crude caprolactam tank 17, and the bottom outlet of the ammonium sulfate separator 15 is connected to the ammonium sulfate primary decomposition device 18 through an ammonium sulfate pump 16.

[0029] Furthermore, the bottom circulation outlet of the neutralization reactor 14 is connected to the circulation inlet of the first mixer 13 through the neutralization circulation pump 12 and the neutralization cooler 11 .

[0030] Furthermore, the ammonia circulation unit includes an ammonia absorption tower 19 connected to the gas phase outlet of the primary ammonium sulfate decomposition device 18. A desalted water inlet is provided at the top of the ammonia absorption tower 19, connected to a desalted water storage tank 20. The liquid phase outlet at the bottom of the ammonia absorption tower 19 is connected to the inlet of the first mixer 13 via an ammonia pump 21. The ammonium sulfate decomposition described in this utility model enables the recycling and reuse of ammonia and sulfuric acid, reducing ammonia and sulfuric acid consumption and significantly lowering production costs for the enterprise.

[0031] Furthermore, a sixth tee 22 and a first valve 30 are sequentially provided between the ammonia water pump 21 and the inlet of the first mixer 13 , and a third end of the sixth tee 22 is connected to the circulation inlet of the ammonia water absorption tower 19 through a second valve 35 .

[0032] The working principle of the utility model is as follows: The process of the utility model mainly involves rearrangement reaction, ammonium sulfate synthesis, ammonium sulfate primary decomposition reaction and ammonium sulfate secondary decomposition reaction. The reaction principle is as follows:

[0033] (1) Rearrangement reaction:

[0034] (2) Ammonium sulfate synthesis: 2NH3+H2SO4→(NH4)2SO4;

[0035] (3) Ammonium sulfate primary decomposition reaction:

[0036] Fe2O3+3(NH4)2SO4→Fe2(SO4)3+6NH3+3H2O;

[0037] (4) Secondary decomposition reaction of ammonium sulfate: Fe2(SO4)3→Fe2O3+3SO3

[0038] Its specific working principle is as follows: the raw material cyclohexanone oxime from the cyclohexanone oxime storage tank 1 enters the primary rearrangement reactor 3 and the secondary rearrangement reactor 7 respectively through the first tee 2; one stream of the rearranged liquid from the primary rearrangement reactor 3 enters the secondary rearrangement reactor 7 through the second tee 8, the secondary circulation pump 9, and the secondary cooler 10 in sequence, while the other stream of the rearranged liquid passes through the seventh tee 4, the primary circulation pump 5, and the primary cooler 6 in sequence and circulates back to the primary rearrangement reactor 3. One stream of the rearranged liquid from the secondary rearrangement reactor 7 merges with the rearranged liquid from the primary rearrangement reactor 3 and passes through the second tee 8, the secondary circulation pump 9, and the secondary cooler 10 in sequence and circulates back to the secondary rearrangement reactor 7, while the other stream enters the first mixer 13 through a pipeline; the primary rearrangement reactor 3 has an operating temperature of 30-150°C and an operating pressure of 0.01-1.0 MPa, while the secondary rearrangement reactor 7 has an operating temperature of 40-165°C and an operating pressure of 0.01-1.0 MPa. The material coming out of the first mixer 13 is transported to the neutralization reactor 14 via a pipeline; the crude caprolactam and ammonium sulfate mixture at the top of the neutralization reactor 14 is transported to the ammonium sulfate separator 15 via a pipeline, and the mixed liquid at the bottom of the neutralization reactor 14 is sequentially passed through the neutralization circulation pump 12 and the neutralization cooler 11 and then enters the first mixer 13. The operating temperature of the neutralization reactor 14 is 30-130°C, and the operating pressure is 0.01-1.0 MPa. The crude caprolactam at the top of the ammonium sulfate separator 15 is separated from the ammonium sulfate and enters the crude caprolactam tank 17. The ammonium sulfate at the bottom is transported to the ammonium sulfate primary decomposition device 18 via an ammonium sulfate pump 16; the operating temperature of the ammonium sulfate primary decomposition device 18 is 380-460°C, and the operating pressure is 0.01-0.6 MPa.The ammonia gas from the top of the ammonium sulfate primary decomposition device 18 enters the ammonia absorption tower 19 through a pipeline, and the desalted water from the desalted water tank 20 enters the ammonia absorption tower 19 through a pipeline. The ammonia water from the bottom of the ammonia absorption tower 19 is sequentially circulated back to the ammonia absorption tower 19 through an ammonia pump 21 and a sixth tee 22 to absorb ammonia gas in a cycle. When the ammonia water reaches a predetermined concentration, it is transported into the first mixer 13 through the ammonia pump 21 and the sixth tee 22. The bottom material of the ammonium sulfate primary decomposition device 18 is sent to the ammonium sulfate secondary decomposition device 23 through a pipeline, and the bottom material of the ammonium sulfate secondary decomposition device 23 is returned to the ammonium sulfate primary decomposition device 18 through a circulation pump 34. The secondary decomposition unit 23 operates at a temperature of 600-750°C and a pressure of 0.01-0.5 MPa. SO₃ gas from the top of the ammonium sulfate secondary decomposition unit 23 flows through a third tee 24, with one stream and water vapor from a water vapor storage tank 25 respectively entering a second mixer 26 via a pipeline, and another stream is piped to an oleum unit 29. The gas-liquid mixture exiting the second mixer 26 flows through a pipeline into a sulfuric acid condenser 28. The concentrated sulfuric acid at the bottom of the sulfuric acid condenser 28 is condensed in a sulfuric acid condenser 27 and then enters the oleum unit 29. The acid gas from the top of the sulfuric acid condenser 28 and the acid gas from the oleum unit 29 flow through a fourth tee 30 and enter an exhaust gas treatment unit 31. Nicotinic acid from the bottom of the oleum unit 29 and nicotinic acid from a nicotinic acid raw material tank 32 enter a fifth tee 33 and then flow through a pipeline to a seventh tee 4. This utility model produces ammonia and SO₃ by decomposing ammonium sulfate. It not only solves the environmental problem of caprolactam enterprises dealing with by-product ammonium sulfate, but also reduces the consumption of liquid ammonia and sulfuric acid raw materials in the equipment. For enterprises in areas with scarce sulfur resources, it reduces the investment in sulfur-based acid production equipment, reduces the overall operating costs of caprolactam production enterprises, and improves the profitability of enterprises.

[0039] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the present invention as claimed.

Claims

1. A caprolactam production device with ammonium sulfate circulation, characterized in that: The device comprises a cyclohexanone oxime storage tank (1), the cyclohexanone oxime storage tank (1) is connected to a caprolactam preparation unit via a rearrangement reaction unit, and the caprolactam preparation unit is connected to an ammonium sulfate recycling unit; The ammonium sulfate recycling unit comprises a multi-stage ammonium sulfate decomposition section arranged in series, wherein the terminal gas phase outlet of the multi-stage ammonium sulfate decomposition section is connected to the nicotinic acid preparation section, and the nicotinic acid preparation section is connected to the rearrangement reaction unit.

2. The caprolactam production device with ammonium sulfate circulation according to claim 1, characterized in that: The multi-stage ammonium sulfate decomposition section comprises an ammonium sulfate primary decomposition device (18) and an ammonium sulfate secondary decomposition device (23), wherein the gas phase outlet of the ammonium sulfate primary decomposition device (18) is connected to the caprolactam preparation unit via an ammonia circulation section, the liquid phase outlet of the ammonium sulfate primary decomposition device (18) is connected to the inlet of the ammonium sulfate secondary decomposition device (23), the liquid phase outlet of the ammonium sulfate secondary decomposition device (23) is connected to the circulation inlet of the ammonium sulfate primary decomposition device (18) via a circulation pump (34), and the gas phase outlet of the ammonium sulfate secondary decomposition device (23) is connected to the nicotinic acid preparation section.

3. The caprolactam production device with ammonium sulfate circulation according to claim 2, characterized in that: The nicotinic acid preparation unit includes a fuming sulfuric acid device (29), a gas phase outlet of an ammonium sulfate secondary decomposition device (23) is connected to the fuming sulfuric acid device (29) via a third tee (24), the fuming sulfuric acid device (29) is connected to a rearrangement reaction unit via a fifth tee (33), and a third end of the fifth tee (33) is connected to a nicotinic acid raw material tank (32); The third end of the third tee (24) is connected to the sulfuric acid condenser (28) through the second mixer (26), the inlet of the second mixer (26) is also connected to the water vapor storage tank (25), and the liquid phase outlet of the sulfuric acid condenser (28) is connected to the liquid phase inlet of the oleum device (29) through the sulfuric acid water cooler (27).

4. The caprolactam production device with ammonium sulfate circulation according to claim 3, characterized in that: The gas phase outlets of the oleum device (29) and the sulfuric acid condenser (28) are respectively connected to the tail gas treatment device (31).

5. The caprolactam production device with ammonium sulfate circulation according to claim 3, characterized in that: The rearrangement reaction unit comprises an outlet of a cyclohexanone oxime storage tank (1) connected to a primary rearrangement reactor (3) and a secondary rearrangement reactor (7) respectively through a first tee (2); a bottom circulation outlet of the primary rearrangement reactor (3) connected to a circulation inlet at the top of the primary rearrangement reactor (3) through a seventh tee (4), a primary circulation pump (5) and a primary cooler (6); the outlet at the top of the primary rearrangement reactor (3) connected to the secondary rearrangement reactor (7); and a third end of the seventh tee (4) connected to a fifth tee (33).

6. The caprolactam production device with ammonium sulfate circulation according to claim 5, characterized in that: The bottom circulation outlet of the secondary rearrangement reactor (7) is connected to the circulation inlet of the upper part of the secondary rearrangement reactor (7) through the second tee (8), the secondary circulation pump (9) and the secondary cooler (10), the third end of the second tee (8) is connected to the outlet of the upper part of the primary rearrangement reactor (3), and the outlet of the upper part of the secondary rearrangement reactor (7) is connected to the caprolactam preparation unit.

7. The caprolactam production device with ammonium sulfate circulation according to claim 6, characterized in that: The caprolactam preparation unit comprises a first mixer (13) connected to the upper outlet of the secondary rearrangement reactor (7), the inlet of the first mixer (13) is also connected to the ammonia circulation unit, the outlet of the first mixer (13) is connected to the inlet of the neutralization reactor (14), the outlet of the neutralization reactor (14) is connected to the inlet of an ammonium sulfate separator (15), the upper outlet of the ammonium sulfate separator (15) is connected to a crude caprolactam tank (17), and the bottom outlet of the ammonium sulfate separator (15) is connected to an ammonium sulfate primary decomposition device (18) via an ammonium sulfate pump (16).

8. The caprolactam production device with ammonium sulfate circulation according to claim 7, characterized in that: The bottom circulation outlet of the neutralization reactor (14) is connected to the circulation inlet of the first mixer (13) through the neutralization circulation pump (12) and the neutralization cooler (11).

9. The caprolactam production device with ammonium sulfate circulation according to claim 7, characterized in that: The ammonia circulation section includes an ammonia absorption tower (19) connected to the gas phase outlet of the ammonium sulfate primary decomposition device (18); a desalted water inlet connected to a desalted water storage tank (20) is provided at the top of the ammonia absorption tower (19); and a liquid phase outlet at the bottom of the ammonia absorption tower (19) is connected to the inlet of the first mixer (13) via an ammonia pump (21).

10. The caprolactam production device with ammonium sulfate circulation according to claim 9, characterized in that: A sixth tee (22) and a first valve (30) are sequentially provided between the ammonia water pump (21) and the inlet of the first mixer (13); a third end of the sixth tee (22) is connected to a circulation inlet in the ammonia water absorption tower (19) via a second valve (35).

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