Reaction system and method for preparing adiponitrile through adipic acid ammonolysis reaction

Abstract

The invention relates to a reaction system and method for preparing adiponitrile through adipic acid ammonolysis reaction, the reaction system comprises an ammonia gas preheater, a batching tank, a supergravity nitrile reactor, a falling film evaporation reaction separator and a separation tower, the batching tank is connected and communicated with the supergravity nitrile reactor through a feeding pipeline; the ammonia gas preheater is connected and communicated with the top of the super-gravity nitrile reactor through a gas inlet pipeline, and the bottom of the super-gravity nitrile reactor is connected and communicated with the top of the super-gravity nitrile reactor through a first circulating pipeline; a central pipe of the supergravity nitrile reactor is connected and communicated with the top of the falling film evaporation reaction separator through a gas outlet pipeline, the first circulating pipeline is connected with a balance pipeline used for being connected with the falling film evaporation reaction separator, and the side part of the falling film evaporation reaction separator is connected and communicated with the separation tower through a side line. According to the invention, the coking tendency in the reactor is greatly reduced, the energy consumption is reduced, the side reaction is reduced, and the product conversion rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical industry, in particular to a reaction system and method for preparing adiponitrile through adipic acid ammoniation reaction. BACKGROUND

[0002] The nitrilation reactor in the existing technology for preparing adiponitrile through adipic acid ammoniation has the problems of small reaction interface, high interface temperature, easy coking, high energy consumption and the like, which affect the long-period operation and economic benefits of the device.

[0003] The nitrilation reactor is the core equipment for producing adiponitrile, and its operation effect directly affects the operation period and economic benefits of the device. Based on the above problems, the development of a new type of efficient nitrilation reaction system is particularly important in the development of the technology for preparing adiponitrile through adipic acid ammoniation.

[0004] The patent for invention with the application publication number CN120227816A discloses a supergravity adiponitrile production system and method. The supergravity adiponitrile production system comprises a supergravity nitrilation reactor, a separation tower, a semi-nitrile evaporator and a refining device. The middle part of the supergravity nitrilation reactor is communicated with the lower part of the separation tower through a main pipeline, and the top part thereof is communicated with a main ammonia gas pipeline. The top part of the separation tower is respectively communicated with an ammonia recovery pipeline and a water recovery pipeline, and the upper part thereof is communicated with the refining device through a pipeline. The top part of the semi-nitrile evaporator is respectively communicated with the bottom part of the separation tower, the main pipeline and the main ammonia gas pipeline through pipelines. The refining device comprises a crude nitrile water washing tank, a decanter, a dehydrator, a top tower and a tail tower which are sequentially communicated through pipelines. The top part of the crude nitrile water washing tank is communicated with the upper part of the separation tower through a pipeline. The lower part of the top tower is communicated with the upper part of the dehydrator through a pipeline I, and the top part of the dehydrator is communicated with a product pipeline. Buffer tanks are respectively fixedly installed on the pipeline I and the product pipeline. Condensers are respectively fixedly installed on the pipeline I and the product pipeline. The two condensers are respectively located at positions between the top tower and one of the buffer tanks on the pipeline I and between the dehydrator and the other buffer tank on the product pipeline. The top parts of the two condensers are respectively communicated with vacuum pipelines. The refining device further comprises a refined adiponitrile storage tank which is communicated with the product pipeline. The lower parts of the top tower and the dehydrator are respectively connected in parallel with reboilers. The bottom part of the dehydrator is communicated with the middle part of the top tower through a pipeline II, and a top tower feed tank is fixedly installed on the pipeline II. The bottom part of the crude nitrile water washing tank is communicated with the top part of the decanter through a pipeline III, and a filter is fixedly installed on the pipeline III.

[0005] The application patent with the application publication number CN120189887A discloses a device for continuously preparing adiponitrile by using supergravity adipic acid, which comprises a falling film assembly, a supergravity assembly, a separation assembly, a mixing assembly and a heater. The bottom of the falling film assembly is connected with the top of the supergravity assembly. The separation assembly is arranged at the lower end of the supergravity assembly and is connected with the supergravity assembly. The heater and the mixing assembly are respectively connected with the inlet of the falling film assembly. The heater is used for heating the ammonia gas for reacting with the reactant in the mixing assembly and sending the ammonia gas into the falling film assembly. The reactant is formed by mixing adipic acid melt and a catalyst. The falling film assembly comprises one or more falling film tubes and a temperature control unit connected with the falling film tubes. The falling film tube is a sleeve structure. The falling film tube contains the reactant and the ammonia gas. The sleeve contains heat exchange liquid. The temperature control unit controls the reaction temperature of the reactant and the ammonia gas by adjusting the temperature of the heat exchange liquid. The falling film assembly further comprises a pressure sensor and a closing door arranged at the inlet of the falling film assembly and a driver arranged on the falling film assembly. The driver is connected with the pressure sensor and drives the closing door to open and close the inlet of the falling film assembly according to the pressure signal of the pressure sensor. SUMMARY

[0006] In order to solve one or more of the technical problems existing in the prior art, the application provides a reaction system and method for preparing adiponitrile by adipic acid ammoniation reaction.

[0007] The technical scheme for solving the above technical problem is as follows: the application provides a reaction system for preparing adiponitrile by adipic acid ammoniation reaction, which comprises an ammonia gas preheater, a batching tank, a supergravity nitrilation reactor, a falling film evaporation reaction separator and a separation tower. The batching tank is connected and communicated with the supergravity nitrilation reactor through a feed pipe. The ammonia gas preheater is connected and communicated with the top of the supergravity nitrilation reactor through a gas inlet pipe. The bottom of the supergravity nitrilation reactor is connected and communicated with the top of itself through a first circulation pipe. The central pipe of the supergravity nitrilation reactor is connected and communicated with the top of the falling film evaporation reaction separator through a gas outlet pipe. The first circulation pipe is connected with a balance pipe for connecting with the falling film evaporation reaction separator. The side of the falling film evaporation reaction separator is connected and communicated with the separation tower through a side line.

[0008] The application has the following beneficial effects: the application sets the supergravity nitrilation reactor, the falling film evaporation reaction separator and the separation tower. The supergravity reaction system uses adipic acid ammoniation method to prepare adiponitrile, strengthens the reaction gas-liquid mass transfer and micro mixing, greatly reduces the coking tendency in the reactor, reduces the energy consumption, reduces the side reaction, improves the product conversion rate, prolongs the stable operation period of the device, greatly reduces the excessive discharge of ammonia gas, thereby reducing the ammonia gas post-treatment cost and the comprehensive preparation cost of adiponitrile.

[0009] On the basis of the above technical scheme, the application can be further improved as follows.

[0010] Further, the first circulation pipeline is sequentially provided with a circulation tank, a reaction circulation pump and a circulation heater along the material circulation direction, the balance pipeline is connected to the first circulation pipeline between the circulation heater and the supergravity nitrilation reactor, and the balance pipeline is in communication with the first circulation pipeline; and the feed pipeline is provided with a preheating circulation pump.

[0011] The beneficial effect of the above further scheme is that the circulation tank can be used as a buffer for the reaction process, so as to avoid the reaction product from directly entering the reaction circulation pump and causing cavitation or cavitation of the reaction circulation pump.

[0012] Further, the bottom of the falling film evaporation reaction separator is connected and communicated with the top of itself through a second circulation pipeline, the second circulation pipeline is provided with a falling film evaporation circulation pump, and a semi-nitrile extraction pipeline is connected to the second circulation pipeline between the falling film evaporation circulation pump and the top of the falling film evaporation reaction separator.

[0013] Further, the bottom of the separation tower is connected and communicated with the side of the falling film evaporation reaction separator through a reflux pipeline.

[0014] Further, the reflux pipeline is connected with a crude adiponitrile extraction pipeline.

[0015] Further, the top of the separation tower is connected with a tower top condenser through a condensing pipeline, the exhaust port of the tower top condenser is connected with a tail gas exhaust pipeline, and the condensate discharge port of the tower top condenser is communicated with the inside of the separation tower through a condensing reflux pipeline.

[0016] Further, the condensing reflux pipeline extends into the separation tower from the side of the separation tower and is connected with a spray head.

[0017] Further, the application further comprises a heating system for heating the batching tank, the circulation tank, the falling film evaporation reaction separator and the separation tower, respectively.

[0018] The beneficial effect of the above further scheme is that the heating system can provide heat for the entire reaction process.

[0019] The application further provides a reaction method for preparing adiponitrile through ammoniation reaction of adipic acid, which is realized by using the reaction system for preparing adiponitrile through ammoniation reaction of adipic acid as described above, and comprises the following steps: S1, opening the material valve at the top of the batching tank, adding adipic acid, diluent and catalyst, and closing the material valve; S2 heats the batching tank, circulating tank, circulating heater, falling film evaporation reaction separator and separation tower through the heating system, so that adipic acid and catalyst are heated to a molten state, and ammonia is preheated to above 160°C through the ammonia preheater. S3, open the valves on the feed line, gas inlet line, first circulation line, gas outlet line and balance line, as well as the circulation pump in the reaction system, and start the hypergravity nitrification reactor to allow adipic acid, catalyst and ammonia to enter the hypergravity nitrification reactor for reaction. S4, the temperature of the circulating tank and the circulating heater is maintained at 220~250℃ by the heating system, and the bottom temperature of the falling film evaporation reaction separator and the separation tower is maintained at 290~320℃ by the heating system; S5, after the preset reaction time, open the valve on the crude adiponitrile collection pipeline connected to the reflux pipeline at the bottom of the separation tower returning to the falling film evaporation reactor to receive the crude adiponitrile product; open the valve on the semi-nitrile collection pipeline connected to the second circulation pipeline at the bottom of the falling film evaporation reactor to receive the semi-nitrile byproduct.

[0020] The beneficial effects of the present invention are: the method of the present invention for preparing adiponitrile by adipic acid ammoniation reaction can overcome the defects of the prior art, such as excessive by-product tar, coking, and reduced reaction efficiency.

[0021] Furthermore, the mass ratio of adipic acid to diluent is 1:1~5, the mass ratio of adipic acid to catalyst is 1:0.001~0.004, and the mass ratio of adipic acid to ammonia is 1:1.5~3.

[0022] The beneficial effects of adopting the above-mentioned further scheme are: by using a reasonable concentration of adipic acid and the ratio of reaction raw materials, the reaction process can be stabilized, and the coking phenomenon can be further reduced.

[0023] This invention provides a reaction system and method for the efficient preparation of adiponitrile from adipic acid via ammoniation. The process involves steps including raw material preheating, high-gravity nitrification reaction, falling film evaporation separation, and dehydration. The reaction system utilizes a high-gravity nitrification reactor to enhance gas-liquid mass transfer, improve micro-mixing, reduce coking tendency, minimize side reactions, and increase product conversion rate. Furthermore, the system separates high-boiling-point byproducts such as semi-nitriles using a falling film evaporation separator, further improving the purity of adiponitrile. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the reaction system for preparing adiponitrile by adipic acid amination reaction according to the present invention; Figure 2 This is a flowchart of a reaction method for preparing adiponitrile by amination of adipic acid according to the present invention.

[0025] The attached diagram lists the components represented by each number as follows: 1. Ammonia preheater; 11. Inlet pipe; 2. Batching tank; 21. Feed pipeline; 22. Preheating circulation pump; 3. High-gravity nitrification reactor; 31. First circulation pipeline; 32. Gas outlet pipeline; 33. Balance pipeline; 34. Circulation tank; 35. Reaction circulation pump; 36. Circulation heater; 4. Falling film evaporator / reactor; 41. Side line; 42. Second circulation pipeline; 43. Falling film evaporator circulation pump; 5. Separation tower; 51. Reflux pipeline; 52. Crude adiponitrile collection pipeline; 53. Condensation pipeline; 54. Tower top condenser; 55. Tail gas discharge pipe; 56. Condensation reflux pipe; 57. Nozzle. Detailed Implementation

[0026] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0027] Example 1 like Figure 1 As shown, a reaction system for preparing adiponitrile by amination of adipic acid in this embodiment includes an ammonia preheater 1, a mixing tank 2, a hypergravity nitrification reactor 3, a falling film evaporation separator 4, and a separation tower 5. The mixing tank 2 is connected to and communicates with the hypergravity nitrification reactor 3 via a feed pipe 21. The ammonia preheater 1 is connected to and communicates with the top of the hypergravity nitrification reactor 3 via an inlet pipe 11. The bottom of the hypergravity nitrification reactor 3 is connected to and communicates with its top via a first circulation pipe 31. The central pipe of the hypergravity nitrification reactor 3 is connected to and communicates with the top of the falling film evaporation separator 4 via an outlet pipe 32. A balance pipe 33 for connecting to the falling film evaporation separator 4 is connected to the first circulation pipe 31. The side of the falling film evaporation separator 4 is connected to and communicates with the separation tower 5 via a side line 41.

[0028] A preferred embodiment of this invention includes a heating system for the amination reaction of adipic acid to prepare adiponitrile. This heating system is used to heat the mixing tank 2, the circulating tank 34, the falling film evaporator separator 4, and the separation tower 5, respectively. By providing the heating system, heat can be supplied for the entire reaction process. Specifically, the heating system may include a heating control unit and a heat-insulating jacket. A heat-insulating jacket can be installed over each piece of equipment or tank requiring heating, and the heating temperature of the heat-insulating jacket can be controlled by the heating control unit. Specifically, heating oil circulation can be used for heating.

[0029] Specifically, in this embodiment, the ammonia preheater 1 is used to preheat ammonia to above 160°C and then transport it to the hypergravity nitrification reactor 3. The hypergravity nitrification reactor 3 operates at a slightly positive pressure and at an operating temperature of 200°C to 260°C. Inside the hypergravity nitrification reactor, excess ammonia reacts with molten adipic acid under catalytic conditions to produce adiponitrile and its byproducts.

[0030] The ultragravity nitrification reactor, falling film evaporation reaction separator, and separation tower in this embodiment can all be commonly used equipment for the preparation of adiponitrile by the adipic acid amination reaction.

[0031] This embodiment utilizes a hypergravity nitrification reactor, falling film evaporation reaction separator, and separation tower to prepare adiponitrile via adipic acid ammoniation in a hypergravity reaction system. This enhances gas-liquid mass transfer and micro-mixing, significantly reduces coking tendency within the reactor, lowers energy consumption, reduces side reactions, improves product conversion rate, and extends the stable operation cycle of the device. Simultaneously, it can significantly reduce excessive ammonia emissions, thereby reducing ammonia post-treatment costs and lowering the overall manufacturing cost of adiponitrile.

[0032] Example 2 Based on Example 1, in this example, the first circulation pipeline 31 is sequentially equipped with a circulation tank 34, a reaction circulation pump 35, and a circulation heater 36 along the material circulation direction. The balance pipeline 33 is connected to the first circulation pipeline 31 between the circulation heater 36 and the hypergravity nitrification reactor 3, and the balance pipeline 33 is in communication with the first circulation pipeline 31. A preheating circulation pump 22 is provided on the feed pipeline 21. By setting up the circulation tank, it can serve as a buffer for the reaction process, preventing reaction products from directly entering the reaction circulation pump and causing cavitation or cavitation of the reaction circulation pump.

[0033] Specifically, in this embodiment, the preheating circulation pump 22 transports the preheated mixture in the batching tank 2 to a molten state to the high-gravity nitrification reactor. The circulating heater 36 can be self-heating, i.e., it has its own heating function, or it can be heated by a heating system.

[0034] In this embodiment, the reactants are returned to the hypergravity nitrification reactor 3 via the circulation tank 34 and the reaction circulation pump 35 to form a reaction cycle. The concentration of adipic acid in the reactants is controlled by controlling the circulation volume, thereby adjusting the reaction efficiency and reducing the tendency to coke.

[0035] Example 3 Based on Example 1 or Example 2, such as Figure 1 As shown, in this embodiment, the bottom of the falling film evaporation reaction separator 4 is connected to its top via a second circulation pipeline 42. A falling film evaporation circulation pump 43 is provided on the second circulation pipeline 42, and a semi-nitrile extraction pipeline is connected to the second circulation pipeline 42 between the falling film evaporation circulation pump 43 and the top of the falling film evaporation reaction separator 4.

[0036] In this embodiment, the gas extracted from the central tube of the supergravity nitrification reactor enters the falling film evaporation reaction separator for separation. The operating temperature inside the falling film evaporation reaction separator is 260℃~320℃. High-boiling-point semi-nitriles and other byproducts are separated at the bottom of the falling film evaporation reaction separator and extracted through the side line of the falling film evaporation circulation pump. The gas phase enters the separation tower.

[0037] In this embodiment, the liquid reactant pumped by the reaction circulation pump 35 enters the falling film evaporation reaction separator 4 for separation. The side stream of the falling film evaporation circulation pump collects high-boiling-point semi-nitriles and other byproducts, while crude adiponitrile enters the separation tower in gaseous form.

[0038] Example 4 Based on any of the above embodiments, such as Figure 1 As shown, in this embodiment, the bottom of the separation tower 5 is connected and communicates with the side of the falling film evaporation reaction separator 4 via a reflux pipe 51 (specifically, it is connected and communicates with the lower side of the falling film evaporation reaction separator 4). A crude adiponitrile collection pipe 52 is connected to the reflux pipe 51.

[0039] Example 5 Based on any of the above embodiments, such as Figure 1 As shown, in this embodiment, the top of the separation tower 5 is connected to a tower top condenser 54 via a condensation pipe 53. The exhaust port of the tower top condenser 54 is connected to a tail gas discharge pipe 55, and the condensate discharge port of the tower top condenser 54 is connected to the interior of the separation tower 5 via a condensate reflux pipe 56. The condensate reflux pipe 56 extends into the separation tower 5 from its side and is connected to a nozzle 57.

[0040] Specifically, the condensate reflux pipe 56 can be extended into the separation tower from the upper side wall of the separation tower 5.

[0041] In this embodiment, the top condenser 54 condenses and refluxes the material, the bottom material is returned to the bottom of the falling film evaporation reaction separator, and gases such as ammonia and water vapor are processed by the tail gas absorption device. Crude adiponitrile product is collected from the bottom of the separation tower.

[0042] The tower top condenser 54 in this embodiment can be a commonly used condenser for preparing adiponitrile by adipic acid ammoniation reaction, and condensation can be achieved by winding condensation pipes around the shell.

[0043] Example 6 This embodiment provides a reaction method for preparing adiponitrile by amination of adipic acid, which is implemented using a reaction system for preparing adiponitrile by amination of adipic acid as described in any of the above embodiments, and includes the following steps: S1, open the material valve at the top of the mixing tank 2, add adipic acid, diluent and catalyst, and close the material valve; S2, the heating system heats the batching tank 2, the circulating tank 34, the circulating heater 36, the falling film evaporation reaction separator 4 and the separation tower 5, so that the adipic acid and the catalyst are heated to a molten state (for example, it can be heated to 160°C, at which point the thermometer on the top of the batching tank 2 shows 160°C), and the ammonia is preheated to above 160°C by the ammonia preheater 1; S3, open the valves on the feed pipe 21, air inlet pipe 11, first circulation pipe 31, air outlet pipe 32 and balance pipe 33 as well as the circulation pump in the reaction system, and start the supergravity nitrification reactor 3 to allow adipic acid, catalyst and ammonia to enter the supergravity nitrification reactor 3 for reaction. S4, the temperature of the circulating tank 34 and the circulating heater 36 is maintained at 220°C (the thermometers at the top of the circulating tank 34 and the circulating heater 36 show 220°C) by the heating system, and the bottom temperature of the falling film evaporation reaction separator 4 and the separation tower 5 is maintained at 290°C by the heating system. S5, after the preset reaction time, open the valve on the crude adiponitrile collection pipeline 52 connected to the reflux pipeline 51 at the bottom of the separation tower 5 to the falling film evaporation reaction separator 4, and receive the crude adiponitrile product; open the valve on the semi-nitrile collection pipeline connected to the second circulation pipeline 42 at the bottom of the falling film evaporation reaction separator 4, and receive the semi-nitrile byproduct.

[0044] In this embodiment, high-boiling-point semi-nitriles and other byproducts are collected from the side stream of the falling film evaporation circulating pump. Ammonia and water vapor are discharged from the top condenser and sent to the tail gas absorption unit for treatment. The top condenser condenses and refluxes the product, and crude adiponitrile is collected from the bottom of the separation tower.

[0045] Specifically, the mass ratio of adipic acid to diluent is 1:2.5, the mass ratio of adipic acid to catalyst is 1:0.0025, and the mass ratio of adipic acid to ammonia is 1:2.5. Using appropriate adipic acid concentrations and reactant ratios can stabilize the reaction process and further reduce coking.

[0046] The method for preparing adiponitrile by adipic acid ammoniation in this embodiment can overcome the defects of existing technologies, such as excessive by-product tar, coking, and reduced reaction efficiency.

[0047] Example 7 This embodiment provides a reaction method for preparing adiponitrile by amination of adipic acid, which is implemented using a reaction system for preparing adiponitrile by amination of adipic acid as described in any of the above embodiments, and includes the following steps: S1, open the material valve at the top of the mixing tank 2, add adipic acid, diluent and catalyst, and close the material valve; S2, through the heating system, the batching tank 2, the circulating tank 34, the circulating heater 36, the falling film evaporation reaction separator 4 and the separation tower 5 are heated to the molten state of adipic acid and catalyst (for example, it can be heated to 180°C, at which point the thermometer on the top of the batching tank 2 shows 180°C), and the ammonia is preheated to above 160°C through the ammonia preheater 1; S3, open the valves on the feed pipe 21, air inlet pipe 11, first circulation pipe 31, air outlet pipe 32 and balance pipe 33 as well as the circulation pump in the reaction system, and start the supergravity nitrification reactor 3 to allow adipic acid, catalyst and ammonia to enter the supergravity nitrification reactor 3 for reaction. S4, the temperature of the circulating tank 34 and the circulating heater 36 is maintained at 230°C (the thermometer at the top of the circulating tank 34 and the circulating heater 36 shows 230°C) by the heating system, and the bottom temperature of the falling film evaporation reaction separator 4 and the separation tower 5 is maintained at 300°C by the heating system. S5, after the preset reaction time, open the valve on the crude adiponitrile collection pipeline 52 connected to the reflux pipeline 51 at the bottom of the separation tower 5 to the falling film evaporation reaction separator 4, and receive the crude adiponitrile product; open the valve on the semi-nitrile collection pipeline connected to the second circulation pipeline 42 at the bottom of the falling film evaporation reaction separator 4, and receive the semi-nitrile byproduct.

[0048] In this embodiment, high-boiling-point semi-nitriles and other byproducts are collected from the side stream of the falling film evaporation circulating pump. Ammonia and water vapor are discharged from the top condenser and sent to the tail gas absorption unit for treatment. The top condenser condenses and refluxes the product, and crude adiponitrile is collected from the bottom of the separation tower.

[0049] Specifically, the mass ratio of adipic acid to diluent is 1:2.5, the mass ratio of adipic acid to catalyst is 1:0.0025, and the mass ratio of adipic acid to ammonia is 1:2.5. Using appropriate adipic acid concentrations and reactant ratios can stabilize the reaction process and further reduce coking.

[0050] The method for preparing adiponitrile by adipic acid ammoniation in this embodiment can overcome the defects of existing technologies, such as excessive by-product tar, coking, and reduced reaction efficiency.

[0051] Example 8 This embodiment provides a reaction method for preparing adiponitrile by amination of adipic acid, which is implemented using a reaction system for preparing adiponitrile by amination of adipic acid as described in any of the above embodiments, and includes the following steps: S1, open the material valve at the top of the mixing tank 2, add adipic acid, diluent and catalyst, and close the material valve; S2, through the heating system, the batching tank 2, the circulating tank 34, the circulating heater 36, the falling film evaporation reaction separator 4 and the separation tower 5 are heated to the molten state of adipic acid and catalyst (for example, it can be heated to 200°C, at which point the thermometer on the top of the batching tank 2 shows 200°C), and the ammonia is preheated to above 160°C through the ammonia preheater 1; S3, open the valves on the feed pipe 21, air inlet pipe 11, first circulation pipe 31, air outlet pipe 32 and balance pipe 33 as well as the circulation pump in the reaction system, and start the supergravity nitrification reactor 3 to allow adipic acid, catalyst and ammonia to enter the supergravity nitrification reactor 3 for reaction. S4, the temperature of the circulating tank 34 and the circulating heater 36 is maintained at 250°C (the thermometer at the top of the circulating tank 34 and the circulating heater 36 shows 250°C) by the heating system, and the bottom temperature of the falling film evaporation reaction separator 4 and the separation tower 5 is maintained at 320°C by the heating system. S5, after the preset reaction time, open the valve on the crude adiponitrile collection pipeline 52 connected to the reflux pipeline 51 at the bottom of the separation tower 5 to the falling film evaporation reaction separator 4, and receive the crude adiponitrile product; open the valve on the semi-nitrile collection pipeline connected to the second circulation pipeline 42 at the bottom of the falling film evaporation reaction separator 4, and receive the semi-nitrile byproduct.

[0052] In this embodiment, high-boiling-point semi-nitriles and other byproducts are collected from the side stream of the falling film evaporation circulating pump. Ammonia and water vapor are discharged from the top condenser and sent to the tail gas absorption unit for treatment. The top condenser condenses and refluxes the product, and crude adiponitrile is collected from the bottom of the separation tower.

[0053] Specifically, the mass ratio of adipic acid to diluent is 1:2.5, the mass ratio of adipic acid to catalyst is 1:0.0025, and the mass ratio of adipic acid to ammonia is 1:2.5. Using appropriate adipic acid concentrations and reactant ratios can stabilize the reaction process and further reduce coking.

[0054] The method for preparing adiponitrile by adipic acid ammoniation in this embodiment can overcome the defects of existing technologies, such as excessive by-product tar, coking, and reduced reaction efficiency.

[0055] Example 9 Based on Example 7, the mass ratio of adipic acid to diluent is 1:1, the mass ratio of adipic acid to catalyst is 1:0.001, the mass ratio of adipic acid to ammonia is 1:1.5, and the rest is the same as in Example 7.

[0056] Example 10 Based on Example 7, the mass ratio of adipic acid to diluent is 1:5, the mass ratio of adipic acid to catalyst is 1:0.004, the mass ratio of adipic acid to ammonia is 1:3, and the rest is the same as in Example 7.

[0057] Test case Experiments were conducted on the coking phenomenon and conversion rate during the preparation of adiponitrile using the reaction methods of Examples 6 to 10.

[0058] An experiment was conducted using a centrifugal reactor to prepare adiponitrile via ammoniation. The reaction conditions were: adipic acid feed rate of 1 kg / h, reaction temperature of 220℃~250℃, and ammonia flow rate of 0.35 kg / h~0.69 kg / h. The highest conversion rate of adipic acid obtained was over 98%, and there was virtually no coking inside the centrifugal reactor after 72 hours of reaction during the preparation of adiponitrile.

[0059] The experimental results show that the present invention can significantly reduce the tendency of coking in the reactor, reduce energy consumption, reduce side reactions, and improve product conversion rate. At the same time, the supergravity nitrification reactor used can significantly reduce the excess ammonia, reduce the cost of ammonia post-treatment, and reduce the overall manufacturing cost of adiponitrile.

[0060] In the description of this invention, it should be understood that the terms "center", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0061] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A reaction system for the preparation of adiponitrile by amination of adipic acid, characterized in that, The system includes an ammonia preheater, a mixing tank, a high-gravity nitrification reactor, a falling film evaporation reaction separator, and a separation tower. The mixing tank is connected to and communicates with the high-gravity nitrification reactor via a feed pipeline. The ammonia preheater is connected to and communicates with the top of the high-gravity nitrification reactor via an inlet pipeline. The bottom of the high-gravity nitrification reactor is connected to and communicates with its top via a first circulation pipeline. The central pipe of the high-gravity nitrification reactor is connected to and communicates with the top of the falling film evaporation reaction separator via an outlet pipeline. The first circulation pipeline is connected to a balance pipeline for connection with the falling film evaporation reaction separator. The side of the falling film evaporation reaction separator is connected to and communicates with the separation tower via a side line.

2. The reaction system for preparing adiponitrile by amination of adipic acid according to claim 1, characterized in that, The first circulation pipeline is provided with a circulation tank, a reaction circulation pump and a circulation heater in sequence along the material circulation direction. The balance pipeline is connected to the first circulation pipeline between the circulation heater and the supergravity nitrification reactor. The balance pipeline is connected to the first circulation pipeline. The feed pipeline is provided with a preheating circulation pump.

3. The reaction system for preparing adiponitrile by amination of adipic acid according to claim 1, characterized in that, The bottom of the falling film evaporation reaction separator is connected to its top via a second circulation pipeline. A falling film evaporation circulation pump is installed on the second circulation pipeline, and a semi-nitrile extraction pipeline is connected between the falling film evaporation circulation pump and the top of the falling film evaporation reaction separator.

4. The reaction system for preparing adiponitrile by amination of adipic acid according to claim 1, characterized in that, The bottom of the separation tower is connected to and communicates with the side of the falling film evaporation reaction separator via a reflux pipeline.

5. The reaction system for preparing adiponitrile by amination of adipic acid according to claim 4, characterized in that, The return pipeline is connected to a crude adiponitrile extraction pipeline.

6. The reaction system for preparing adiponitrile by amination of adipic acid according to claim 1, characterized in that, The top of the separation tower is connected to a tower top condenser via a condensation pipe. The exhaust port of the tower top condenser is connected to a tail gas discharge pipe. The condensate discharge port of the tower top condenser is connected to the interior of the separation tower via a condensate reflux pipe.

7. The reaction system for preparing adiponitrile by amination of adipic acid according to claim 6, characterized in that, The condensate reflux pipe extends from the side of the separation tower into the separation tower and is connected to a nozzle.

8. The reaction system for preparing adiponitrile by amination of adipic acid according to claim 1, characterized in that, It also includes a heating system for heating the batching tank, the circulating tank, the falling film evaporation reaction separator, and the separation tower, respectively.

9. A reaction method for preparing adiponitrile by amination of adipic acid, characterized in that, This is achieved using the reaction system for the preparation of adiponitrile by amination of adipic acid as described in any one of claims 1 to 8. Includes the following steps: S1, open the material valve at the top of the mixing tank, add adipic acid, diluent and catalyst, and close the material valve; S2 heats the batching tank, circulating tank, circulating heater, falling film evaporation reaction separator and separation tower through the heating system, so that adipic acid and catalyst are heated to a molten state, and ammonia is preheated to above 160°C through the ammonia preheater. S3, open the valves on the feed line, gas inlet line, first circulation line, gas outlet line and balance line, as well as the circulation pump in the reaction system, and start the hypergravity nitrification reactor to allow adipic acid, catalyst and ammonia to enter the hypergravity nitrification reactor for reaction. S4, the temperature of the circulating tank and the circulating heater is maintained at 220~250℃ by the heating system, and the bottom temperature of the falling film evaporation reaction separator and the separation tower is maintained at 290~320℃ by the heating system; S5, after the preset reaction time, open the valve on the crude adiponitrile collection pipeline connected to the reflux pipeline at the bottom of the separation tower returning to the falling film evaporation reaction separator, and receive the crude adiponitrile product; Open the valve on the semi-nitrile collection pipeline connected to the second circulation pipeline at the bottom of the falling film evaporator to receive the semi-nitrile byproduct.

10. The reaction method for preparing adiponitrile by amination of adipic acid according to claim 9, characterized in that, The mass ratio of adipic acid to diluent is 1:1~5, the mass ratio of adipic acid to catalyst is 1:0.001~0.004, and the mass ratio of adipic acid to ammonia is 1:1.5~3.

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