Adiponitrile preparation device and method based on falling film reactor

Abstract

The invention belongs to the technical field of organic matter synthesis, and discloses an adiponitrile preparation device and method based on a falling film reactor. The stirring assembly and the falling film reactor are adopted, and the stirring assembly can achieve further uniform dispersion and rapid dehydration of liquid flowing out of the falling film tube. Meanwhile, heat supply is not needed in the stirring assembly, the temperature of the liquid can be further reduced, and side reactions after the materials enter the gas-liquid separation tank are reduced. In the reaction process, liquids such as adipic acid and adiponitrile are uniformly dispersed in a gas phase, the local concentration is prevented from being too high in the heating process, water is rapidly separated in the reaction process, and the product yield is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and relates to an adiponitrile preparation device and method based on a falling film reactor. Background Art

[0002] The reactions involved in the preparation of adiponitrile by ammoniation of adipic acid can be divided into a neutralization reaction and a nitrilation dehydration reaction. The reaction is divided into two steps: neutralization and nitrilation dehydration. The neutralization reaction rate is relatively fast. At 250 °C, the reaction half-life is 5 - 12 s; the nitrilation reaction rate is relatively slow, and the reaction half-life is ~50 min. However, both the neutralization reaction and the nitrilation dehydration process are endothermic processes with a large reaction heat. It has been found that adipic acid decomposes (>220 °C starts to decompose) to form cyclopentanone during the reaction process, and the formed cyclopentanone will undergo self-condensation at high temperatures. At the same time, a high local temperature will also cause adiponitrile to polymerize to form adiponitrile dimer.

[0003] Therefore, the control step of this process is the heat supply process, and the key is how to achieve rapid and uniform heat supply during the reaction process.

[0004] Patent CN 113264847 A discloses a method for preparing adiponitrile. The preparation method includes steps of a first hydrocyanation reaction, an isomerization reaction, and a second hydrocyanation reaction. The preparation method uses a porous polymer-nickel catalyst instead of a traditional homogeneous catalyst for the reaction. The catalyst can be recycled in the reaction system through simple separation, simplifying the catalyst separation and recovery steps. Moreover, the number of catalyst recycling times is greatly increased, reducing the catalyst cost and making industrial production easier to achieve.

[0005] Patent CN 112830878 A discloses a synthesis system and method for preparing hexamethylenediamine by hydrogenation of adiponitrile. The synthesis system includes: an adiponitrile preparation device, a microinterface intensifier, a hydrogenation reaction kettle, and a rectification column connected in sequence. Hydrogen and adiponitrile prepared from the adiponitrile preparation device are introduced into the microinterface intensifier. The synthesis system provided by the present invention optimizes the reaction route, improves the reaction separation efficiency, improves the mass transfer effect at the reaction phase interface, and thus improves the product quality and yield.

[0006] The above-disclosed adiponitrile preparation methods have complex synthesis processes, increasing production costs. Liquids such as adipic acid and adiponitrile in the reaction process cannot be evenly dispersed in the gas phase, resulting in too high a local concentration during the heating process and rapid separation of water during the reaction process, reducing the product yield. Summary of the Invention

[0007] In order to overcome the deficiencies of the prior art, the present invention provides an adiponitrile preparation device and method based on a falling film reactor, which can keep liquids such as adipic acid and adiponitrile evenly dispersed in the gas phase during the reaction process, avoid excessive local concentration during the heating process, rapidly separate water during the reaction process, and improve the product yield.

[0008] The present invention provides an adiponitrile preparation device and method based on a falling film reactor, which adopts a stirring component and a falling film reactor. The stirring component can further evenly disperse and rapidly dehydrate the liquid discharged from the falling film tube. At the same time, no heat supply is required inside the stirring component, which can further reduce the liquid temperature and reduce side reactions after the material enters the gas-liquid separation tank (the residence time in the gas-liquid separation tank is relatively long).

[0009] The above object of the present invention is achieved by the following technical solutions:

[0010] An adiponitrile preparation device based on a falling film reactor includes a falling film reactor and a stirring component; the falling film reactor is arranged above the stirring component, a mixing component for mixing materials is arranged at the top of the falling film reactor, an ammonia inlet pipeline is externally connected to the falling film reactor, a heater for heating ammonia is arranged on the ammonia inlet pipeline, and the bottom of the stirring component is connected to a gas-liquid separation tank through a pipeline.

[0011] The falling film reactor includes a plurality of falling film tubes, the falling film tubes are of a sleeve structure, and a heat exchange liquid is introduced into the sleeve of the falling film tube to control the reaction temperature of the reaction materials and ammonia in the falling film tubes.

[0012] The stirring component includes a stirring tank, a stirring paddle is arranged in the stirring tank, the stirring paddle is equipped with a motor, and the motor is a servo motor.

[0013] The stirring paddle includes a stirring rod and a plurality of blades, the plurality of blades are cross-arranged on the stirring rod, and the surface of each blade is subjected to a hydrophobic treatment. The hydrophobic treatment is not particularly limited as long as the hydrophobic function is achieved.

[0014] A plurality of through holes are arranged on the blade, and the through holes are concentrated at the free end of the blade.

[0015] An elastic membrane layer is arranged in the through hole.

[0016] The falling film reactor is also equipped with a temperature sensor.

[0017] The mixing component includes a mixing tank, the mixing tank is connected to a material tank through a pipeline, and the mixing tank is arranged above the falling film reactor. The mixing tank is also connected to the ammonia inlet pipeline through a pipeline. The material tank is also connected to a phosphoric acid tank body through a pipeline, and 75wt% phosphoric acid is placed in the phosphoric acid tank body.

[0018] Adipic acid molten liquid is placed in the material tank body.

[0019] A steam heater is also provided on the outer periphery of the gas-liquid separation tank. The steam heater includes a steam heating jacket, and a steam inlet and a steam outlet are respectively provided on both sides of the steam heating jacket.

[0020] A product detection pipeline is provided at the bottom of the gas-liquid separation tank, and a butterfly valve is also provided on the product detection pipeline. The bottom of the gas-liquid separation tank is also connected to the mixing tank of the mixing assembly through a circulation pipeline, and a circulation pump is also provided on the circulation pipeline.

[0021] A gas discharge pipeline is also provided at the top of the gas-liquid separation tank, and a condenser, an alkali washing tank, and a vacuum pump are sequentially arranged on the gas discharge pipeline.

[0022] Further, more than one falling film tube is provided, and the specific number of settings can be determined according to the specific requirements of the working conditions.

[0023] Further, a butterfly valve and a temperature sensor are provided on the ammonia inlet pipeline.

[0024] The above device is also equipped with a PLC control system. The butterfly valve, temperature sensor, motor, condenser, circulation pump, heater, vacuum pump, and steam heater are respectively connected to the PLC control system, and there is no limitation to a specific model, as long as its specific working functions can be realized.

[0025] The present invention also requests protection for a method for preparing adiponitrile using the above device: introducing the molten adipic acid solution and the catalyst into the mixing assembly to form a reaction material; introducing the reaction material and ammonia into the falling film reactor to react to obtain a gas-liquid mixture; introducing the gas-liquid mixture into the stirring assembly for reaction to obtain a reaction product; and performing gas-liquid separation on the reaction product to obtain adiponitrile.

[0026] The falling film reactor can introduce the reaction material and ammonia, and the reaction material and ammonia are mixed in the falling film reactor to form a gas-liquid mixture. The temperature sensor provided in the falling film reactor can monitor the reaction temperature; and the signal is fed back to the PLC control system to further control the reaction temperature.

[0027] The device adopts a stirring assembly + tubular falling film reactor. The falling film reactor is arranged at the upper part, and the stirring assembly is arranged at the lower part. Specifically, during use, heated ammonia is used to bring the material into the falling film tube of the falling film reactor at the inlet of the falling film reactor to uniformly disperse the liquid phase. The gas-liquid mixture from the falling film tube of the falling film reactor enters the stirring assembly at the same time to continue the reaction. After the material exits the stirring assembly, it enters the gas-liquid separation tank to obtain adiponitrile.

[0028] The beneficial effects of the present invention compared with the prior art are:

[0029] The adiponitrile preparation device based on a falling film reactor provided by the present invention keeps liquids such as adipic acid and adiponitrile evenly dispersed in the gas phase during the reaction process, avoids excessive local concentration during the heating process, rapidly separates water during the reaction process, and improves the product yield.

[0030] The adiponitrile preparation device and method based on a falling film reactor provided by the present invention adopt a combination of a stirring assembly and a falling film reactor. The stirring assembly can further evenly disperse and rapidly dehydrate the liquid flowing out of the falling film tube. At the same time, no heat supply is required inside the stirring assembly, which can further reduce the liquid temperature and reduce side reactions after the material enters the gas-liquid separation tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the present invention or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a flowchart for preparing adiponitrile based on a falling film reactor according to the present invention.

[0033] Figure 2 It is a schematic diagram of the blade structure.

[0034] Figure 3 It is a schematic diagram of the elastic membrane layer.

[0035] In the figure: 1. material tank, 2. mixing assembly, 3. falling film reactor, 4. stirring assembly, 5. gas-liquid separation tank, 6. heater, 7. circulation pipeline, 8. circulation pump, 9. storage tank, 10. condenser, 11. cooling water inlet, 12. caustic scrubber, 13. vacuum pump, 14. stirring paddle, 15. blade, 16. free end of the blade, 17. elastic membrane layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present invention belong to the protection scope of the present invention.

[0037] The present invention will be described in detail below through specific embodiments, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained from commercial channels.

[0038] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for distinction and should not be construed as indicating or implying relative importance.

[0039] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] To make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the drawings.

[0041] Embodiment 1

[0042] An adiponitrile preparation device based on a falling film reactor, comprising a falling film reactor 3 and a stirring assembly 4; the falling film reactor 3 is arranged above the stirring assembly 4, a mixing assembly 2 for mixing materials is arranged at the top of the falling film reactor 3, the falling film reactor 3 is externally connected to an ammonia inlet pipeline, a heater 6 for heating ammonia is arranged on the ammonia inlet pipeline, and the bottom of the stirring assembly 4 is connected to a gas-liquid separation tank 5 through a pipeline.

[0043] The falling film reactor 3 includes a plurality of falling film tubes, the falling film tubes are of a casing structure, and a heat exchange liquid is introduced into the casing of the falling film tubes to control the reaction temperature of the reaction materials and ammonia in the falling film tubes. The reaction temperature in the falling film tubes is monitored by a temperature sensor, and the signal is fed back to the PLC control system. If the temperature is higher than the reaction temperature, an instruction is given by the PLC to adjust and lower the temperature of the heat exchange liquid. If the temperature is lower than the reaction temperature, an instruction is given by the PLC to adjust and increase the temperature of the heat exchange liquid.

[0044] The stirring assembly 4 includes a stirring tank, a stirring paddle 14 is arranged in the stirring tank, and the stirring paddle 14 is equipped with a motor, and the motor is a servo motor.

[0045] The stirring paddle 14 includes a stirring rod and a plurality of blades 15, the plurality of blades 15 are cross-arranged on the stirring rod, and the surface of each blade 15 is subjected to a hydrophobic treatment. The hydrophobic treatment is not particularly limited as long as the hydrophobic function is achieved.

[0046] A plurality of through holes are arranged on the blade 15, and the through holes are concentrated at the free end 16 of the blade.

[0047] An elastic membrane layer 17 is arranged in the through hole.

[0048] The falling film reactor 3 is also equipped with a temperature sensor.

[0049] The mixing assembly 2 includes a mixing tank. The mixing tank is connected to the material tank 1 through a pipeline, and the mixing tank is arranged above the falling film reactor 3. The mixing tank is also connected to the ammonia inlet pipeline through a pipeline. The material tank 1 is also connected to the phosphoric acid tank body through a pipeline, and 75wt% phosphoric acid is placed in the phosphoric acid tank body.

[0050] Adipic acid molten liquid is placed in the material tank 1.

[0051] A steam heater is also arranged on the outer periphery of the gas-liquid separation tank 5. The steam heater includes a steam heating sleeve, and a steam inlet and a steam outlet are respectively arranged on both sides of the steam heating sleeve.

[0052] A product detection pipeline is arranged at the bottom of the gas-liquid separation tank 5, and a butterfly valve is also arranged on the product detection pipeline. The bottom of the gas-liquid separation tank 5 is also connected to the mixing tank of the mixing assembly 2 through a circulation pipeline 7, and a circulation pump 8 is also arranged on the circulation pipeline 7.

[0053] A gas discharge pipeline is also arranged at the top of the gas-liquid separation tank 5, and a condenser 10, an alkali washing tank 12, and a vacuum pump 13 are sequentially arranged on the gas discharge pipeline.

[0054] More than one falling film tube is arranged, and the specific number of arrangements can be set according to the specific requirements of the working conditions.

[0055] A butterfly valve and a temperature sensor are arranged on the ammonia inlet pipeline.

[0056] The above device is also equipped with a PLC control system. The butterfly valve, temperature sensor, motor, condenser 10, circulation pump 8, heater 6, vacuum pump 13, and steam heater are respectively connected to the PLC control system, and a specific model is not limited, as long as its specific working functions can be realized.

[0057] The present invention also claims a method for preparing adiponitrile by using the above device: introducing adipic acid molten liquid and a catalyst into the mixing assembly 2 to be mixed to form a reaction material; introducing the reaction material and ammonia into the falling film reactor 3 to react to obtain a gas-liquid mixture; introducing the gas-liquid mixture into the stirring assembly 4 to react to obtain a reaction product; and performing gas-liquid separation on the reaction product to obtain adiponitrile.

[0058] The falling film reactor 3 can introduce the reaction material and ammonia. The reaction material and ammonia are mixed in the falling film reactor 3 to form a gas-liquid mixture. The temperature sensor arranged in the falling film reactor 3 can monitor the reaction temperature; and the signal is fed back to the PLC control system to further control the reaction temperature.

[0059] In this embodiment, a stirring assembly + tubular falling film reactor 3 is adopted. The falling film reactor 3 is arranged at the upper part, and the stirring assembly 4 is arranged at the lower part. The reaction materials flow into the falling film reactor 3 by themselves, and the heated ammonia gas is used to bring the reaction materials into the falling film tube at the inlet of the falling film reactor 3, so that the liquid phase is uniformly dispersed, and the gas-liquid is fully mixed and reacted in the falling film tube. The temperature sensor and the PLC control system can control the reaction temperature between 200 - 220 °C. The gas-liquid mixture flowing out of the falling film tube enters the stirring assembly 4 at the same time to continue the reaction. After the materials flow out of the stirring assembly 4, they enter the gas-liquid separation tank 5, and are sampled and analyzed from the bottom of the gas-liquid separation tank 5 to calculate the single-pass conversion rate. If the multi-pass conversion rate is to be investigated, a circulating pump 8 and a circulating pipeline 7 can be used to circulate the materials for the test.

[0060] The stirring assembly 4 can further uniformly disperse the liquid flowing out of the falling film tube and quickly dehydrate it. At the same time, no heat supply is required inside the stirring assembly 4, which can further reduce the liquid temperature and reduce the side reactions after the materials enter the gas-liquid separation tank 5 (the residence time in the gas-liquid separation tank is relatively long). By adopting a specially defined gas-carrying liquid mixing feeding method, the liquid in the falling film tube can be dispersed as uniformly as possible, and at the same time, by precisely controlling the temperature, the occurrence of side reactions can be reduced.

[0061] The above-described embodiments are only the preferred embodiments of the present invention, and not all the feasible embodiments of the present invention. For those of ordinary skill in the art, any obvious changes made without departing from the principles and spirit of the present invention should be considered to be included within the protection scope of the claims of the present invention. Although the present invention has been described above with reference to the embodiments, various improvements can be made to it and its components can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no technical conflict, the various features in the disclosed embodiments of the present invention can be combined with each other in any way. The exhaustive description of these combinations is omitted in this specification only for the sake of saving space and resources. Therefore, the present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A device for preparing adiponitrile based on a falling film reactor, characterized in that, it includes a falling film reactor (3) and a stirring assembly (4); the falling film reactor (3) is arranged above the stirring assembly (4), a mixing assembly (2) for mixing materials is arranged at the top of the falling film reactor (3), the falling film reactor (3) is externally connected to an ammonia inlet pipeline, a heater (6) for heating ammonia is arranged on the ammonia inlet pipeline, and the bottom of the stirring assembly (4) is connected to a gas-liquid separation tank (5) through a pipeline.

2. The device for preparing adiponitrile based on a falling film reactor according to claim 1, characterized in that, the falling film reactor (3) includes a plurality of falling film tubes, the falling film tubes are of a sleeve structure, and a heat exchange liquid is introduced into the sleeve of the falling film tube to control the reaction temperature of the reaction materials and ammonia in the falling film tube.

3. The device for preparing adiponitrile based on a falling film reactor according to claim 1, characterized in that, the stirring assembly (4) includes a stirring tank, a stirring paddle (14) is arranged in the stirring tank, and the stirring paddle (14) is equipped with a motor.

4. The device for preparing adiponitrile based on a falling film reactor according to claim 1, characterized in that, the mixing assembly (2) includes a mixing tank, the mixing tank is connected to a material tank (1) through a pipeline, and the mixing tank is arranged above the falling film reactor (3); the mixing tank is also connected to the ammonia inlet pipeline through a pipeline.

5. The device for preparing adiponitrile based on a falling film reactor according to claim 1, characterized in that, a steam heater is further arranged on the outer periphery of the gas-liquid separation tank (5), the steam heater includes a steam heating sleeve, and a steam inlet and a steam outlet are respectively arranged on both sides of the steam heating sleeve.

6. The device for preparing adiponitrile based on a falling film reactor according to claim 1, characterized in that, a product detection pipeline is arranged at the bottom of the gas-liquid separation tank (5), and a butterfly valve is further arranged on the product detection pipeline.

7. The device for preparing adiponitrile based on a falling film reactor according to claim 1, characterized in that, the bottom of the gas-liquid separation tank (5) is further connected to the mixing tank of the mixing assembly (2) through a circulation pipeline (7), and a circulation pump (8) is further arranged on the circulation pipeline (7).

8. The device for preparing adiponitrile based on a falling film reactor according to claim 3, characterized in that, the stirring paddle (14) includes a stirring rod and a plurality of blades (15), the plurality of blades (15) are cross-arranged on the stirring rod, and the surface of each blade (15) is treated with hydrophobic treatment.

9. The device for preparing adiponitrile based on a falling film reactor according to claim 8, characterized in that, a plurality of through holes are arranged on the blade (15), and the through holes are concentrated at the free end (16) of the blade; an elastic membrane layer (17) is arranged in the through holes.

10. A method for preparing adiponitrile by using the device for preparing adiponitrile based on a falling film reactor according to any one of claims 1-9, characterized in that, Introduce the molten adipic acid solution and the catalyst into the mixing assembly (2) to form a reaction material by mixing; introduce the reaction material and ammonia gas into the falling film reactor (3) to react to obtain a gas-liquid mixture; introduce the gas-liquid mixture into the stirring assembly (4) for reaction to obtain a reaction product; perform gas-liquid separation on the reaction product to obtain adiponitrile.

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