A jet rearrangement reaction device and a lactam preparation method

Abstract

The application discloses a jet flow type rearrangement reaction device and a lactam preparation method, and mainly relates to the technical field of lactam production. The device comprises a reaction tube, a gas nozzle, a gas distributor and a liquid nozzle mechanism are sequentially arranged in the reaction tube from top to bottom, a liquid storage tank is arranged at the bottom end of the reactor and is communicated with the reactor, the gas nozzle is used for spraying the gas phase reactant downward, the liquid nozzle mechanism is used for spraying the liquid phase catalyst from the liquid storage tank upward, the liquid nozzle mechanism comprises at least two liquid nozzles arranged along the height direction, and an acid catalyst supplementing port is arranged at the bottom of the liquid storage tank. The application has the beneficial effects that: through the two-stage jet flow device specially designed, the micro-Bekman rearrangement reaction is carried out in the mode that the continuous liquid flow and the dispersed gas flow collide to form a foam area, the efficient contact of the gas and the liquid is realized, the reaction efficiency is remarkably improved, and the problem of uneven mixing of the reaction raw materials in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of lactam production technology, specifically a jet-type rearrangement reaction apparatus and a method for preparing lactam. Background Technology

[0002] More than 90% of the world's lactams are prepared by the Beckmann rearrangement of ketoximes. Specifically, ketoximes undergo Beckmann molecular rearrangement under the catalysis of concentrated sulfuric acid or fuming sulfuric acid to form a mixture of lactam and sulfuric acid, which is then purified to obtain high-purity lactams.

[0003] For large-scale industrial production, traditional liquid-phase reactors are either batch or fixed-bed reactors, which use stirring or circulation systems to ensure sufficient contact between reactants and catalysts. The Beckmann rearrangement is a strongly exothermic reaction. Traditional batch reactors have limited heat transfer area, easily leading to uneven stirring and localized overheating. Fixed-bed reactors also suffer from uneven internal temperature distribution. Localized overheating reduces product selectivity, increases byproducts, accelerates catalyst depletion, and in severe cases, can cause a rapid increase in pressure, posing an explosion risk.

[0004] In particular, for the cyclododecanone oxime rearrangement reaction, since the melting point of dodecylactam is higher than the reaction temperature, using stirring or circulation to intensify the reaction process easily leads to crystallization of the reaction products, resulting in changes in the rheological properties of the system, a sharp increase in stirring power, and even damage to the equipment. Even if a high-power stirrer is selected, the excessively high energy consumption is unacceptable for industrial-scale processes. Summary of the Invention

[0005] The purpose of this invention is to provide a jet-type rearrangement reaction device and a method for preparing lactams. It uses a specially designed two-stage jet device to carry out a micro-Beckmann rearrangement reaction by using the collision of continuous liquid flow and dispersed gas flow to form a foam zone. This achieves efficient gas-liquid contact, significantly improves reaction efficiency, and solves the problem of uneven mixing of reaction raw materials in the prior art.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A jet-type rearrangement reaction device includes a reaction tube, in which a gas nozzle, a gas distributor, and a liquid nozzle mechanism are arranged sequentially from top to bottom. A storage tank communicating with the bottom of the reactor is provided. The gas nozzle is used to spray gaseous reactants downward, and the liquid nozzle mechanism is used to spray liquid catalyst from the storage tank upward. The liquid nozzle mechanism includes at least two liquid nozzles arranged in a vertical direction. The bottom of the storage tank is provided with a bottom-mounted acid catalyst replenishment port.

[0008] A buffer tank is provided upstream of the reaction tube. The buffer tank is connected to a raw material inlet and a nitrogen replenishment port. The buffer tank is connected to the gas nozzle.

[0009] The upper part of the storage tank is connected to an upright exhaust pipe. The bottom end of the exhaust pipe is submerged below the liquid surface of the storage tank. The bottom side wall of the exhaust pipe is provided with an exhaust port located inside the storage tank. The top end of the exhaust pipe is provided with a gas outlet, which is connected to the buffer tank.

[0010] The exhaust pipe is provided with a packing layer, a sprayer, and a demister in sequence from bottom to top. A vacuum compressor and a gas heat exchanger are also provided between the gas outlet and the buffer tank. The vacuum compressor is provided with a condensate discharge port.

[0011] The bottom of the storage tank is connected to a circulating liquid outlet, and a circulating pipeline equipped with a circulating pump is connected to the circulating liquid outlet. A liquid heat exchanger is provided on the circulating pipeline, and the circulating pipeline is connected to the liquid nozzle mechanism for liquid supply.

[0012] The gas distributor is a sieve plate structure with its edges sealed and fixed to the inner wall of the reaction tube. The opening ratio of the gas distributor is 30%-60%, and the opening diameter is 0.5-2mm.

[0013] And / or, the inner wall of the reaction tube is covered with an anti-adhesion coating, the anti-adhesion coating being set according to the coverage area when the liquid nozzle mechanism is working;

[0014] And / or, the gas nozzle is a swirling nozzle with internal guide vanes, the nozzle diameter is 2-5mm, the spray angle is 30-60°, and the spray velocity is 8-15m / s.

[0015] A plurality of spiral plate coolers are provided in the reaction tube between the gas distributor and the liquid nozzle mechanism. The spiral plate coolers extend along the vortex line and the cooling medium flows inside. The outer surface of the spiral plate coolers is provided with a layer of micropores formed by electrochemical corrosion. The micropore diameter is 10-20 μm and the micropore depth is 30-50 μm.

[0016] The liquid nozzle mechanism includes a primary liquid nozzle and a secondary liquid nozzle arranged vertically within the reaction tube. The primary liquid nozzle is a multi-hole liquid column nozzle with a diameter of 1-3 mm, a spray angle of 50-70°, and a spray velocity of 2-3 m / s. The secondary liquid nozzle is a fine atomizing nozzle with multiple internal swirling blades, and the spray shape is a hollow cone. The secondary liquid nozzle has a diameter of 1-3 mm, a spray angle of 60-120°, and a spray velocity of 1-2 m / s. The liquid outlet temperature of the primary and secondary liquid nozzles is 50-70°C.

[0017] A method for preparing lactam, using the above-mentioned jet-type rearrangement reaction apparatus, includes the following steps: gaseous ketoxime is pulsed and sprayed downward through a gas nozzle in a swirling motion; the liquid-phase catalyst sprayed through the gas distributor and the liquid nozzle mechanism below first forms a stable foam zone, and then an atomization zone is formed below the foam zone; the reaction product enters the storage tank; after replenishing the catalyst, it is circulated back to the liquid nozzle mechanism.

[0018] The ejection temperature of the gas nozzle is 100-350℃. The gaseous ketoxime enters the gas nozzle under the protection of inert gas, and the ratio of gaseous ketoxime to inert circulating gas is 1:1 to 1:1.5.

[0019] And / or, in the foam zone, the gas-liquid ratio of the two-phase reaction is 100-160:1, and the molar ratio of catalyst to ketoxime is 1.6:1-2.5:1;

[0020] And / or, the reaction system in the foam zone is cooled.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This jet-type rearrangement reaction device utilizes a specially designed two-stage jet system. The first-stage jet uses the opposing flow of continuous liquid and dispersed gas to form a high-speed turbulent foam zone. After mixing in the foam zone, the gas and liquid phases flow downstream and are then atomized by the second-stage jet. The raw materials and catalyst undergo two microscopic Beckmann rearrangement reactions in the foam and atomization zones, which significantly improves the reaction efficiency of the lactam preparation method of this invention, enhances the heat and mass transfer process, prevents local overheating, results in low impurity content in by-products, and ensures stable product properties without altering their rheological properties. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the present invention.

[0024] Figure 2 This is a schematic diagram of a spiral plate cooler.

[0025] The labels shown in the attached diagram:

[0026] 1. Reaction tube; 2. Gas nozzle; 3. Primary liquid nozzle; 4. Secondary liquid nozzle; 5. Liquid heat exchanger; 6. Circulating pump; 7. Liquid storage tank; 8. Exhaust pipe; 9. Packing layer; 10. Sprayer; 11. Demister; 12. Vacuum compressor; 13. Gas heat exchanger; 14. Pulse buffer tank; 17. Circulating pipeline; 18. Circulating gas path; 101. Gas distributor; 102. Spiral plate cooler; 103. Anti-adhesion coating. Detailed Implementation

[0027] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0028] Lactams are important monomers for the preparation of nylon materials. They are usually prepared by the Beckmann rearrangement of ketoximes under concentrated sulfuric acid catalysis. The rearranged mixture is then purified to obtain high-purity lactams.

[0029] Existing rearrangement methods suffer from low mass and heat transfer efficiency, high catalyst loss, and high operating costs. Traditional stirred tank or fixed-bed reactors have low heat transfer efficiency, and the heat accumulation during reaction can cause localized overheating of ketoximes during rearrangement, leading to thermal condensation, carbon deposition, and coking, which affects the stable operation of the unit. Uneven mass transfer within the system can also result in excessive impurities in the generated lactam, increasing the difficulty of purification and adversely affecting subsequent polymerization.

[0030] To improve the efficiency of the Beckmann rearrangement reaction, this technology focuses on improving the reactor structure to enhance the mixing effect of raw materials.

[0031] (I) Reactor Structure

[0032] The reactor includes a reaction tube 1, which is a vertically installed reaction vessel. From top to bottom, the reaction tube 1 is equipped with a gas nozzle 2, a gas distributor 101, a spiral plate cooler 102 (two layers), a primary liquid nozzle 3, and a secondary liquid nozzle 4. The bottom end of the reaction tube 1 is provided with a liquid storage tank 7 that is sealed and connected to it.

[0033] Above the reaction tube 1 is a buffer tank connected to the material therein. The buffer tank is connected to a raw material inlet (N1) and a nitrogen supply port (N2). The raw material inlet is used to connect gaseous ketoxime, and the nitrogen supply port is used to connect inert gas. Based on the above structure, the buffer tank is used to mix gaseous ketoxime with inert circulating gas.

[0034] The top of the reaction tube 1 is equipped with a gas nozzle 2. The buffer tank and the gas nozzle 2 are connected by a pipeline with a solenoid valve. The solenoid valve is a high-speed solenoid valve, which is controlled by an external waveform generator to make the mixed gas flow out in the form of sinusoidal pulses. The pulse frequency can be adjusted in the range of 0.5-2 Hz, and the flow fluctuation amplitude is ±10% to ±20% of the reference flow rate.

[0035] The gas nozzle 2 is a swirling nozzle with internal guide vanes. Its diameter is 2-5mm, the spray angle is 30-60°, the spray velocity is 8-15m / s, and the gas temperature is controlled at 100-350℃.

[0036] A gas distributor 101 is installed 50-300 mm below the gas nozzle 2. The gas distributor 101 is a sieve plate type, and its edge is sealed and fixed to the inner wall of the reaction tube 1. The opening ratio of the gas distributor 101 is 30%-60%, and the opening diameter is 0.5-2 mm. After the pulsed airflow impacts the distributor, it is further broken up and evenly distributed, forming a stable and uniform downward airflow across the entire cross-section of the reaction tube 1.

[0037] Below the gas distributor 101, a foam zone is formed in the reaction system. A double-layered spiral plate cooler 102 is installed in this zone, such as... Figure 2 As shown, the spiral plate cooler 102 is made of corrosion-resistant metal tubes wound together, with a cooling medium flowing inside. The outer surface of the spiral tubes is electrochemically corroded to form a uniform porous microstructure with pore diameters of 10-20 μm and depths of 30-50 μm. This structure significantly increases the heat exchange area, enabling efficient in-situ removal of reaction heat and preventing localized overheating. Furthermore, it provides abundant nucleation sites for bubbles, promoting the formation of finer, more uniform foams and synergistically enhancing mass and heat transfer.

[0038] After the reaction is complete, the foam bursts, and the resulting droplets flow downwards. The inner wall of reaction tube 1, downstream of the foam zone and extending to the product outlet, is covered with an anti-adhesion coating 103. This coating is a modified ceramic coating with a static contact angle greater than 110° with the acidic catalyst, exhibiting extremely low surface energy and excellent acid resistance. It effectively prevents acidic droplets from spreading and adhering to the wall surface, promoting rapid aggregation and downward flow of the droplets. This significantly shortens the residence time of the product on the high-temperature wall surface, inhibiting the formation of heavy components and coking.

[0039] Below the foam zone, at the bottom of reaction tube 1, is the liquid nozzle mechanism. This system includes primary liquid nozzles 3 and secondary liquid nozzles 4, distributed vertically, to achieve secondary exchange in the reaction sequence. Primary liquid nozzle 3 is a multi-hole liquid column nozzle with a diameter of 1-3 mm, a spray angle of 50-70°, a spray velocity of 2-3 m / s, and a liquid outlet temperature controlled within the range of 50-70℃. Secondary liquid nozzle 4 is a multi-head fine atomizing nozzle with internal swirl blades, a diameter of 1-3 mm, a spray angle of 60-120°, a spray velocity of 1-2 m / s, and a hollow cone-shaped spray pattern. The liquid outlet temperature is also controlled within the range of 50-70℃.

[0040] The bottom of the storage tank 7 is connected to a circulating liquid outlet (N3) and a catalyst replenishment port (N4). The catalyst replenishment port replenishes acid catalyst according to the concentration of the catalyst circulating outlet. A circulation pipeline 17 with a circulation pump 6 is connected to the circulating liquid outlet. A liquid heat exchanger 5 is installed on the circulation pipeline 17. The circulation pipeline 17 is connected to the primary liquid nozzle 3 and the secondary liquid nozzle 4 for liquid supply.

[0041] The reaction products fall into the storage tank 7, and the circulating liquid is pumped to the primary liquid nozzle and the secondary liquid nozzle through the circulation pipeline 17. The liquid heat exchanger 5 is used to cool the acid catalyst, and the cooling water flow rate of the heat exchanger is adjusted according to the catalyst outlet temperature.

[0042] The storage tank 7 is also provided with a product outlet (N5), which is located above the catalyst replenishment port (N4) and the circulating liquid outlet (N3). The mixture of the reaction product lactam and part of the acid catalyst and heavy component by-products is discharged through the product outlet (N5) and enters the extraction separation and washing process.

[0043] The upper part of the storage tank 7 is connected to an upright exhaust pipe 8, which is arranged in parallel with the reaction tube 1. The bottom end of the exhaust pipe 8 is inserted below the liquid surface in the storage tank 7. An exhaust port is provided on the bottom side wall of the exhaust pipe 8. Gas and some acidic droplets in the upper part of the storage tank 7 enter the exhaust pipe 8 from the exhaust port in the form of mist.

[0044] The middle part of the exhaust pipe 8 is filled with a packing layer 9, which is a ceramic Pall ring packing or a polypropylene Pall ring. A sprayer 10 is provided above the packing layer 9. A spray water inlet (N6) is connected to the side wall of the exhaust pipe 8 above the sprayer 10 to provide spray water to the sprayer 10. The sprayer 10 and the absorbent packing layer 9 are used to purify the gas and recover the acid catalyst. A demister 11 is provided above the packing layer 9 at the top of the exhaust pipe 8 to further trap mist in the gas.

[0045] The exhaust pipe 8 is provided with a gas outlet (N7) at the top, and a circulating gas path 18 is connected to the gas outlet (N7). The circulating gas path 18 is connected to the buffer tank and circulates the treated gas to the reaction system.

[0046] The circulating gas path 18 is provided with a vacuum compressor 12 and a gas heat exchanger 13 in sequence according to the gas direction. The vacuum compressor 12 is connected to a condensate discharge port (N8). The discharged gas is pressurized by the compressor, and the condensate is discharged from the intermediate tank of the compressor unit. The non-condensable gas is cooled by the gas heat exchanger 13. After being cooled to the required temperature, it is mixed with fresh raw material gas and the circulation is completed through the buffer tank.

[0047] The cooling water flow rate of the liquid heat exchanger 5 is adjusted according to the catalyst circulation outlet temperature; the cooling water flow rate of the gas heat exchanger 13 is adjusted according to the gas inlet temperature of the reaction tube 1, thereby achieving optimized energy allocation of the entire system.

[0048] (ii) Optimize rearrangement reaction

[0049] Based on the improved reactor described above, a lactam rearrangement reaction is carried out. The reaction process, which involves reactants, gas phase, and liquid phase passing through this reactor, is a cyclic reaction. Starting from the buffer tank section, the reaction is described below according to the material sequence and flow direction.

[0050] Gas-phase ketoxime enters the buffer tank through the raw material inlet (N1), and inert gas enters the buffer tank through the nitrogen replenishment port (N2). The two are mixed evenly in the buffer tank, and after being regulated by the outlet solenoid valve, they enter the reaction tube 1 in a pulse form and are sprayed out through the gas nozzle 2 in a swirling manner. The temperature is controlled within the range of 100-350℃, and the ratio of gas-phase ketoxime to inert circulating gas is 1:1 to 1:1.5.

[0051] The gaseous ketoxime ejected by the swirling jet is evenly dispersed in the reaction tube 1 by the gas distributor 101, and forms a stable foam zone at the momentum equilibrium point with the liquid catalyst column of 50-70℃ ejected by the first-stage liquid nozzle 3 below. The gas-liquid ratio of the two-phase reaction is 100-160:1, and the molar ratio of catalyst to ketoxime is 1.6:1-2.5:1.

[0052] The foam zone is 20-50cm high and is cooled by the spiral plate cooler 102. The atomized droplets sprayed from the descending liquid flow secondary liquid nozzle 4 meet and form an atomization zone with a height of 5-10cm. The unreacted ketoxime continues to undergo rearrangement reaction with the catalyst here to ensure that the final conversion rate reaches the maximum.

[0053] After the reaction, the product enters the storage tank 7. The storage tank 7 is replenished with acid catalyst according to the concentration at the catalyst circulation outlet. The liquid phase is supplied to the primary liquid nozzle 3 and the secondary liquid nozzle 4 through the circulation liquid outlet.

[0054] The upper reaction product is discharged through the product outlet (N5) and enters the neutralization reactor and extraction tower to extract lactam;

[0055] Nitrogen and SO3 entrained with sulfuric acid mist and gaseous organic matter in the gas phase space of storage tank 7 enter the discharge pipe. SO3 and sulfuric acid mist are absorbed by demineralized water and returned to storage tank 7. Non-condensable gas is pressurized and its temperature is adjusted by vacuum compressor 12, and then mixed with new raw material gas in a buffer tank for recycling. Concentrated sulfuric acid discharged with the reaction products is replenished by 104% fuming sulfuric acid at the bottom of storage tank 7.

[0056] The improved solution has the following beneficial effects:

[0057] 1) By utilizing the collision between continuous liquid flow and dispersed gas flow to form a foam zone, the micro-Beckmann rearrangement reaction is carried out, achieving efficient gas-liquid contact, significantly improving reaction efficiency, and solving the problem of uneven mixing of reaction raw materials in the prior art.

[0058] 2) The gas and liquid phase nozzles are designed independently. By adjusting the temperature and relative flow rate, a stable foam layer is formed at the momentum equilibrium point of the gas and liquid phases, which effectively prevents the problem of increased by-products caused by local overheating.

[0059] 3) By setting up a two-stage hollow cone atomizing nozzle, the liquid phase reaction time is extended, and the raw material conversion rate and catalyst selectivity are improved.

[0060] 4) By setting up a storage tank and a catalyst circulation system, automatic replenishment and recycling of the catalyst are achieved, reducing operating costs.

[0061] 5) A demister and spray system were installed at the gas outlet, which effectively reduced the system temperature, reduced catalyst loss and pollutant generation, and improved the operational stability of the unit.

[0062] 6) The structure is simple and reliable, and the operation is flexible, making it suitable for large-scale industrial production.

[0063] Example 1:

[0064] In the lactam rearrangement reaction, cyclic ketoxime gas and nitrogen are mixed in a 1:1 ratio at 300℃ in a buffer tank. The mixture is regulated by an outlet solenoid valve and enters the upper part of the reaction tube in a 2Hz pulsating sinusoidal wave pattern with a pulsation amplitude of ±10%. The mixed gas is ejected from a swirling nozzle with a 3.5mm diameter and internal guide vanes, at a 30° spray angle and a gas velocity of 12m / s. After impacting a sieve-type distribution plate, the gas is further dispersed evenly. 98% concentrated sulfuric acid catalyst is ejected from bottom to top through a primary liquid nozzle. This primary liquid nozzle is a porous liquid column nozzle with a 2mm diameter, a 60° spray angle, and a spray velocity of 2m / s. The ejected liquid column is a solid cone shape with uniform distribution. A foam zone with a height of 35cm is formed at the momentum equilibrium point between the gas and liquid streams. The gas-liquid ratio of the two phases is 130:1, and the molar ratio of concentrated sulfuric acid to ketoxime is 3:1. A spiral plate cooler, made of HC-276 tubing, is installed in the foam zone. It is circulated with 30°C cooling water. The outer surface of the spiral tube undergoes electrochemical corrosion treatment to form a uniform porous microstructure with pore diameters of 10 μm and depths of 30 μm. After the reaction, the foam bursts, and droplets rapidly converge and flow down the inner wall of the reactor, which is coated with a modified ceramic layer. This flow mixes again with concentrated sulfuric acid sprayed from the secondary liquid nozzle. The secondary liquid nozzle is a 7-nozzle fine atomizing nozzle with internal swirl blades, a nozzle diameter of 1.5 mm, a jet velocity of 1.5 m / s, and a hollow cone spray shape, forming a 5 cm atomization zone with the descending droplets. Approximately 10% of the unreacted liquid cyclic ketoximes in the foam zone continue to undergo rearrangement reactions with the concentrated sulfuric acid. The reaction products enter a storage tank, while some products enter a neutralization reactor and an extraction tower to extract lactams. Excess concentrated sulfuric acid is mixed with the product and recycled.

[0065] Nitrogen and SO3 entrained with sulfuric acid mist and gaseous organic matter in the gas phase space of the storage tank enter the discharge pipe. SO3 and sulfuric acid mist are absorbed by demineralized water and returned to the storage tank. Non-condensable gas is pressurized and its temperature is adjusted by a vacuum compressor, and then mixed with new raw material gas in a buffer tank for recycling. Concentrated sulfuric acid discharged with the reaction products is replenished by 104% fuming sulfuric acid at the bottom of the storage tank.

[0066] Example 2:

[0067] In the lactam rearrangement reaction, cyclic ketoxime gas and nitrogen are mixed in a 1:1.5 ratio at 100℃ in a buffer tank. The mixture is regulated by an outlet solenoid valve and enters the upper part of the reaction tube in a 0.5Hz pulsating sine wave pattern, with a pulsation amplitude of ±15%. The mixed gas is ejected from a swirling nozzle with a 2mm diameter and internal guide vanes, at a 50° spray angle and a gas velocity of 8m / s. After impacting a sieve-type distribution plate, the gas is further dispersed evenly. 100% concentrated sulfuric acid catalyst is ejected from bottom to top through a primary liquid nozzle. This primary liquid nozzle is a porous liquid column nozzle with a 1mm diameter, a 50° spray angle, and a spray velocity of 1.5m / s. The ejected liquid column is a solid cone shape with uniform distribution. A foam zone with a height of 20cm is formed at the momentum equilibrium point between the gas and liquid streams. The gas-liquid ratio of the two phases is 100:1, and the molar ratio of concentrated sulfuric acid to ketoxime is 3:1. A spiral plate cooler, made of HC-276 tubing, is installed in the foam zone. It is circulated with 30°C cooling water. The outer surface of the spiral tube undergoes electrochemical corrosion treatment to form a uniform porous microstructure with pore diameters of 20 μm and depths of 35 μm. After the reaction, the foam bursts, and droplets rapidly converge and flow down the inner wall of the reactor, which is coated with a modified ceramic layer. This flow mixes again with concentrated sulfuric acid sprayed from the secondary liquid nozzle. The secondary liquid nozzle is a 7-nozzle fine atomizing nozzle with internal swirl blades, a 1 mm diameter nozzle, a jet velocity of 1 m / s, and a hollow cone spray shape, forming an 8 cm atomization zone with the descending droplets. Approximately 10% of the unreacted liquid cyclic ketoximes in the foam zone continue to undergo rearrangement reactions with the concentrated sulfuric acid. The reaction products enter a storage tank, while some products enter a neutralization reactor and an extraction tower to extract lactams. Excess concentrated sulfuric acid is mixed with the product and recycled.

[0068] Nitrogen and SO3 entrained with sulfuric acid mist and gaseous organic matter in the gas phase space of the storage tank enter the discharge pipe. SO3 and sulfuric acid mist are absorbed by demineralized water and returned to the storage tank. Non-condensable gas is pressurized and its temperature is adjusted by a vacuum compressor, and then mixed with new raw material gas in a buffer tank for recycling. Concentrated sulfuric acid discharged with the reaction products is replenished by 104% fuming sulfuric acid at the bottom of the storage tank.

[0069] Example 3:

[0070] In the lactam rearrangement reaction, cyclic ketoxime gas and nitrogen gas are mixed in a 1:1.2 ratio in a buffer tank at 350℃. The mixture is regulated by an outlet solenoid valve and enters the upper part of the reaction tube in a 1Hz pulsating sine wave pattern with a pulsation amplitude of ±20%. The mixed gas is ejected from a swirl nozzle with a 5mm diameter and internal guide vanes, a 60° spray angle, and a gas velocity of 15m / s. After impacting a sieve-type distribution plate, the gas is further dispersed evenly. 98% concentrated sulfuric acid catalyst is ejected from bottom to top through a primary liquid nozzle with a 3mm diameter, a 70° spray angle, and a spray velocity of 3m / s. The ejected liquid column is a solid cone shape with uniform distribution. A foam zone with a height of 50cm is formed at the momentum equilibrium point between the gas and liquid streams. The gas-liquid ratio of the two phases is 160:1, and the molar ratio of concentrated sulfuric acid to ketoxime is 3:1. A spiral plate cooler, made of HC-276 tubing, is installed in the foam zone. It is circulated with 30°C cooling water. The outer surface of the spiral tube undergoes electrochemical corrosion treatment to form a uniform porous microstructure with pore diameters of 15μm and depths of 50μm. After the reaction, the foam bursts, and droplets rapidly converge and flow down the inner wall of the reactor, which is coated with a modified ceramic layer. This flow mixes again with concentrated sulfuric acid sprayed from the secondary liquid nozzle. The secondary liquid nozzle is a 7-nozzle fine atomizing nozzle with internal swirl blades, a 3mm diameter nozzle, a jet velocity of 2m / s, and a hollow cone spray shape, forming a 10cm atomization zone with the descending droplets. Approximately 10% of the unreacted liquid cyclic ketoximes in the foam zone continue to undergo rearrangement reactions with the concentrated sulfuric acid. The product enters a storage tank, and a portion of the product enters a neutralization reactor and an extraction tower to extract lactams. Excess concentrated sulfuric acid is mixed with the product and recycled.

[0071] Nitrogen and SO3 entrained with sulfuric acid mist and gaseous organic matter in the gas phase space of the storage tank enter the discharge pipe. SO3 and sulfuric acid mist are absorbed by demineralized water and returned to the storage tank. Non-condensable gas is pressurized and its temperature is adjusted by a vacuum compressor, and then mixed with new raw material gas in a buffer tank for recycling. Concentrated sulfuric acid discharged with the reaction products is replenished by 104% fuming sulfuric acid at the bottom of the storage tank.

[0072] It should be noted that the above description is a further detailed explanation of the present invention in conjunction with specific embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple improvements and modifications can be made without departing from the concept of the present invention, and all such improvements and modifications should be considered to fall within the scope of protection of the present invention.

Claims

1. A jet-type rearrangement reaction device, characterized in that, The reactor includes a reaction tube, and from top to bottom, a gas nozzle, a gas distributor, and a liquid nozzle mechanism are arranged in sequence inside the reaction tube. The bottom end of the reactor is provided with a liquid storage tank connected to it. The gas nozzle is used to spray gaseous reactants downward, and the liquid nozzle mechanism is used to spray liquid catalyst from the liquid storage tank upward. The liquid nozzle mechanism includes at least two liquid nozzles arranged in a vertical direction. The bottom of the liquid storage tank is provided with a bottom acid catalyst replenishment port.

2. The jet-type rearrangement reaction device according to claim 1, characterized in that, A buffer tank is provided upstream of the reaction tube. The buffer tank is connected to a raw material inlet and a nitrogen replenishment port. The buffer tank is connected to the gas nozzle.

3. The jet-type rearrangement reaction device according to claim 2, characterized in that, The upper part of the storage tank is connected to an upright exhaust pipe. The bottom end of the exhaust pipe is submerged below the liquid surface of the storage tank. The bottom side wall of the exhaust pipe is provided with an exhaust port located inside the storage tank. The top end of the exhaust pipe is provided with a gas outlet, which is connected to the buffer tank.

4. The jet-type rearrangement reaction device according to claim 3, characterized in that, The exhaust pipe is provided with a packing layer, a sprayer, and a demister in sequence from bottom to top. A vacuum compressor and a gas heat exchanger are also provided between the gas outlet and the buffer tank. The vacuum compressor is provided with a condensate discharge port.

5. The jet-type rearrangement reaction device according to claim 1, characterized in that, The bottom of the storage tank is connected to a circulating liquid outlet, and a circulating pipeline equipped with a circulating pump is connected to the circulating liquid outlet. A liquid heat exchanger is provided on the circulating pipeline, and the circulating pipeline is connected to the liquid nozzle mechanism for liquid supply.

6. The jet-type rearrangement reaction device according to claim 1, characterized in that, The gas distributor is a sieve plate structure with its edges sealed and fixed to the inner wall of the reaction tube. The opening ratio of the gas distributor is 30%-60%, and the opening diameter is 0.5-2mm. And / or, the inner wall of the reaction tube is covered with an anti-adhesion coating, the anti-adhesion coating being set according to the coverage area when the liquid nozzle mechanism is working; And / or, the gas nozzle is a swirling nozzle with internal guide vanes, the nozzle diameter is 2-5mm, the spray angle is 30-60°, and the spray velocity is 8-15m / s.

7. The jet-type rearrangement reaction device according to claim 1, characterized in that, A plurality of spiral plate coolers are provided in the reaction tube between the gas distributor and the liquid nozzle mechanism. The spiral plate coolers extend along the vortex line and the cooling medium flows inside. The outer surface of the spiral plate coolers is provided with a layer of micropores formed by electrochemical corrosion. The micropore diameter is 10-20 μm and the micropore depth is 30-50 μm.

8. The jet-type rearrangement reaction device according to claim 1, characterized in that, The liquid nozzle mechanism includes a primary liquid nozzle and a secondary liquid nozzle arranged vertically within the reaction tube. The primary liquid nozzle is a multi-hole liquid column nozzle with a diameter of 1-3 mm, a spray angle of 50-70°, and a spray velocity of 2-3 m / s. The secondary liquid nozzle is a fine atomizing nozzle with multiple internal swirling blades, and the spray shape is a hollow cone. The secondary liquid nozzle has a diameter of 1-3 mm, a spray angle of 60-120°, and a spray velocity of 1-2 m / s. The liquid outlet temperature of the primary and secondary liquid nozzles is 50-70°C.

9. A method for preparing lactam, characterized in that, Production is carried out using a jet-type rearrangement reaction apparatus as described in any one of claims 1-9, and includes the following steps: gaseous ketoxime is pulsed and sprayed downward through a gas nozzle in a swirling manner; the liquid-phase catalyst sprayed through the gas distributor and the liquid nozzle mechanism below first forms a stable foam zone, and then an atomization zone is formed below the foam zone; the reaction product enters the storage tank; after replenishing the catalyst, it is circulated back to the liquid nozzle mechanism.

10. The method for preparing lactam according to claim 9, characterized in that, The ejection temperature of the gas nozzle is 100-350℃. The gaseous ketoxime enters the gas nozzle under the protection of inert gas, and the ratio of gaseous ketoxime to inert circulating gas is 1:1 to 1:1.

5. And / or, in the foam zone, the gas-liquid ratio of the two-phase reaction is 100-160:1, and the molar ratio of catalyst to ketoxime is 1.6:1-2.5:1; And / or, the reaction system in the foam zone is cooled.

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