A multi-stage fixed bed gas phase amination continuous reaction complete system

Abstract

The application discloses a kind of multistage fixed bed gas phase amination continuous reaction complete system, belong to multistage fixed bed gas phase amination technical field, including following module: raw material processing module, for pressurizing and converting liquid ammonia and alcohol into gas phase state;Multi-stage reaction module;Gas-liquid separation module;Circulation pressurization module;Product refining module;Energy integration module;The application breaks the inherent contradiction of conversion rate and selectivity mutual restriction by the function differentiation and synergistic coupling of three reaction zones;First reaction zone is accurately anchored bed inlet temperature by inlet temperature adjustment function, limit adiabatic temperature rise at a level much lower than existing process, inhibit the chain amplification of side reaction caused by "fly temperature";Second reaction zone breaks the thermodynamic equilibrium limit of single-stage reaction by interstage feed and enhanced mixing function;Third reaction zone is stable in the window interval of side reaction inhibition by constant temperature control function, and intercept upstream impurities.

Description

Technical Field

[0001] This invention relates to the field of multi-stage fixed-bed gas-phase amination technology, and more specifically, to a complete system for continuous multi-stage fixed-bed gas-phase amination reaction. Background Technology

[0002] Gas-phase amination is the core process for preparing aliphatic amines. Industrially, a single-stage adiabatic fixed-bed reactor is commonly used, where alcohols and ammonia undergo a gas-phase hydrogen-induced reaction under the action of a catalyst to produce primary amines. This reaction is strongly exothermic, with a single-stage adiabatic temperature rise reaching 80–120°C. Localized overheating of the bed can easily lead to "runaway" temperatures, resulting in a surge of side reactions such as dehydrogenation and cyclization. The selectivity for primary amines is typically only 80%–85%. Simultaneously, limited by thermodynamic equilibrium, the single-pass conversion rate is only 60%–70%. Industrially, an excess ammonia-to-alcohol ratio of 5–10 times is used to drive equilibrium, causing a large amount of unreacted ammonia and alcohol to enter the separation system, increasing the load on ammonia recovery towers and azeotropic distillation towers. The load is extremely high, resulting in high steam consumption and equipment investment. In terms of energy utilization, the existing process only recovers the waste heat of the high-temperature section through a waste heat boiler, while the heat in the medium-temperature section is directly lost, and the system thermal efficiency is usually less than 60%. The gas-liquid separation process uses wire mesh or cyclone separators, and the efficiency of removing submicron-sized droplets decreases with operating time. The entrained material corrodes the compressor impeller, becoming a common cause of unplanned shutdowns. The catalyst slowly deactivates due to carbon buildup, requiring shutdown for unloading and high-temperature carbon burning regeneration, with a regeneration cycle of 48 to 72 hours. Frequent thermal shocks reduce the catalyst life to generally no more than 2 years, and a large number of defective products during start-up and shutdown further reduce the plant's operating rate.

[0003] Therefore, we have made improvements to this and proposed a multi-stage fixed-bed gas-phase amination continuous reaction system. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, the purpose of this invention is to provide a complete set of multi-stage fixed-bed gas-phase amination continuous reaction system.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: it includes the following modules: The raw material processing module is used to pressurize liquid ammonia and alcohols and convert them into a gaseous state. The multi-stage reaction module consists of a first reaction zone, a second reaction zone, and a third reaction zone connected in series. The first reaction zone is equipped with an inlet temperature regulation function, the second reaction zone is equipped with an interstage feeding and enhanced mixing function, and the third reaction zone is equipped with a constant temperature control function. The gas-liquid separation module is used to separate reaction products into gaseous and liquid streams. A circulating pressurization module is used to pressurize the gaseous stream and send it back to the raw material processing module; The product refining module is used to separate the liquid phase stream into product stream and return stream; An energy integration module is used to recover the heat released by the reaction and convert it into the mechanical energy and cooling required within the system.

[0006] Preferably, the inlet temperature regulation function of the first reaction zone is achieved by injecting a circulating medium with a temperature lower than that of the reaction stream into the feed stream, so as to control the inlet temperature of the catalyst bed within a set range and reduce the temperature rise of the reaction zone caused by the exothermic reaction to a predetermined level; a resistance monitoring function is provided at the outlet of the first reaction zone to feed back the bed status signal to the system control terminal.

[0007] Preferably, the interstage feeding and enhanced mixing function of the second reaction zone includes: receiving unreacted streams from the first reaction zone and injecting supplementary preheated alcohol vapor and cooling medium to achieve component and temperature regulation; simultaneously, applying a supersonic jet effect to the mixture stream, causing the supplementary liquid to be torn into micro-scale droplets and instantly and completely vaporized in an alternating flow field of shock waves and expansion waves, with the adiabatic compression temperature rise caused by the shock wave serving as an internal heat source for raising the temperature of the supplementary stream to the reaction activation energy; the enhanced mixed stream enters the second reaction zone for deep conversion, where the temperature rise is limited to below a predetermined level, and the output of the second reaction zone merges with the unreacted material from the first reaction zone before entering the third reaction zone.

[0008] Preferably, the constant temperature control function of the third reaction zone is achieved by adjusting the heat exchange rate between the reaction zone and the external heat medium to maintain the reaction temperature near the set point; the third reaction zone also has an adsorption filtration function to intercept impurities entrained in the upstream stream; each of the three reaction zones is equipped with on / off control and pressure release functions, and the interstage pressure drop design value is, for example, 0.05 MPa; the outlet of the third reaction zone is equipped with a composition monitoring function to obtain the content information of target components and by-products in the product in real time and transmit the information to the system control terminal to adjust the feed rate and cooling medium injection rate.

[0009] Preferably, the raw material processing module includes a pressurization function, a metering function, a two-stage heat exchange function, and an evaporation function. Liquid ammonia and alcohols are pressurized to, for example, 3.0-3.5 MPa by the pressurization function, and then transported by the metering function into the first stage of the two-stage heat exchange function. They are preheated by the sensible heat of the high-temperature reaction products from the third reaction zone. The preheated liquid enters the evaporation function and is converted into vapor under pressure. The vapor enters the second stage of the two-stage heat exchange function and mixes with the reflux gas from the circulating pressurization module to form a homogeneous reaction mixture with an adjustable ammonia-to-alcohol molar ratio in the range of 4:1 to 6:1, which is then sent to the first reaction zone.

[0010] Preferably, the energy integration module includes a three-stage heat utilization function: the first-stage heat utilization function receives the high-temperature reaction product stream from the third reaction zone, transfers its heat to the working medium to generate low-pressure steam, and at the same time, the temperature of the reaction product drops to a first intermediate temperature; the second-stage heat utilization function uses the reaction product at the first intermediate temperature to preheat the liquid ammonia and alcohols entering the raw material processing module, so that the reaction product is further reduced to a second intermediate temperature; the third-stage heat utilization function cools the reaction product at the second intermediate temperature to the target temperature with a cooling medium and then sends it to the gas-liquid separation module.

[0011] Preferably, the gas-liquid separation module includes a high-pressure separation function and an ultrasonic coalescence demisting function; the high-pressure separation function is used to separate the cooled reaction products into a gaseous stream and a liquid stream under high pressure; the ultrasonic coalescence demisting function is set on the outlet channel of the gaseous stream, and by applying a traveling wave sound field, the fine droplets entrained in the gaseous stream migrate, collide and coalesce into large droplets under the action of sound radiation force, and then naturally settle back to the high-pressure separation zone; the gaseous stream after demisting enters the enrichment function, selectively discharges some inert gas to maintain the stability of the partial pressure of the active atmosphere in the system, and the gaseous stream enriched with active components enters the circulation pressurization module to be pressurized to the threshold and then returns to the raw material processing module.

[0012] Preferably, the liquid phase stream outlet of the gas-liquid separation module is connected to a hydraulic expansion functional unit, and there is a direct mechanical work transmission coupling relationship between the hydraulic expansion functional unit and the circulating pressurization module; the high-pressure liquid phase stream from the high-pressure separation function enters the hydraulic expansion functional unit, outputs mechanical work through the depressurization process and provides part of the driving power for the circulating pressurization module, and at the same time, the temperature of the liquid phase stream is significantly reduced after isentropic expansion. This low-temperature stream is introduced into the top condensation function of the product refining module as the only cold source, completely replacing the external refrigeration supply; The model for the work done and temperature drop during the isentropic expansion process is as follows: ; in, The output shaft power, The mass flow rate of the liquid stream. This is the inlet liquid phase enthalpy. For isentropic efficiency, and These are the inlet pressure and the outlet pressure, respectively. The equivalent adiabatic index of the liquid. For the actual temperature drop, This refers to the inlet temperature.

[0013] Preferably, the product refining module receives the liquid phase stream after it has been depressurized and cooled by the hydraulic expansion function unit, and separates it into a light component vapor stream and a heavy component liquid stream within the refining function; the light component vapor stream is condensed by the top condensation function and then sent to the reflux separation function, and the reflux phase rich in unreacted substances is completely sent back to the inlet of the raw material processing module, realizing a zero-emission liquid phase closed loop of unreacted substances.

[0014] Preferably, it also includes a microwave energy input module. When the resistance of any reaction zone reaches the set trigger value, the system control terminal automatically reduces the feed load of the reaction zone and isolates it from the main process through a bypass. Then, the microwave energy input is started for in-situ regeneration. The microwave frequency is selected according to the difference in dielectric properties between the carbon deposits and the catalytically active substances in the reaction zone, so that the carbon deposits preferentially absorb microwave energy to heat up to the vaporization temperature and are removed. At the same time, the temperature of the catalytically active substances is maintained at a temperature much lower than their sintering temperature, shortening the regeneration cycle to 6-8 hours. After completion, it switches back to the main process to realize alternating regeneration and continuous operation. The microwave selective heating power calculation model is as follows: ; in, The microwave power absorbed by the object being heated. This is the microwave operating frequency. The vacuum permittivity, The effective dielectric loss factor of the object being heated. Let be the root-mean-square electric field strength inside the cavity. This refers to the catalyst bed volume; Energy closed-loop efficiency is expressed as: ; in, For global energy efficiency, The increase in chemical energy carried by the target product. The heat is converted from the mechanical work recovered by hydraulic expansion. To calculate the calorific value of the refrigeration capacity for isentropic expansion, The sum of physical and chemical heat introduced by fresh raw materials. This is the heat equivalent to the net electrical power consumed by the circulating booster module after deducting the recovered power. The calorific value is calculated based on the electrical energy consumed by microwave regeneration.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By functional differentiation and synergistic coupling of the three-stage reaction zones, the inherent contradiction between conversion rate and selectivity is broken; the first reaction zone precisely anchors the bed inlet temperature through the inlet temperature regulation function, limiting the adiabatic temperature rise to a level far lower than that of existing processes, thus suppressing the chain amplification of side reactions caused by "runaway temperature"; the second reaction zone breaks through the thermodynamic equilibrium limitation of single-stage reaction through interstage feeding and enhanced mixing functions; the third reaction zone stabilizes the reaction temperature within the window range where side reactions are suppressed through the constant temperature control function, and intercepts upstream impurities.

[0016] 2. By organically combining the energy integration module with the hydraulic expansion function, a full-spectrum energy self-recovery system covering high, medium and low temperature grades and including mechanical work and cooling output is constructed; the low-pressure steam by-product of high-temperature reaction is directly supplied to the raw material evaporation and distillation reboiling, the medium-temperature waste heat is used to preheat the feed, and the high-pressure liquid phase outputs mechanical work through hydraulic expansion to provide part of the power for the circulation pressurization. At the same time, isentropic expansion cooling becomes the only cold source for the top condensation of the distillation, replacing the external chilled water. Attached Figure Description

[0017] Figure 1 This application provides an architecture diagram of a multi-stage fixed-bed gas-phase amination continuous reaction system. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] A multi-stage fixed-bed gas-phase amination continuous reaction system includes the following modules: The raw material processing module is used to pressurize liquid ammonia and alcohols and convert them into a gaseous state. The multi-stage reaction module consists of a first reaction zone, a second reaction zone, and a third reaction zone connected in series. The first reaction zone is equipped with an inlet temperature regulation function, the second reaction zone is equipped with interstage feeding and enhanced mixing functions, and the third reaction zone is equipped with a constant temperature control function. The gas-liquid separation module is used to separate reaction products into gaseous and liquid streams. The circulating booster module is used to pressurize the gaseous stream and send it back to the raw material processing module; The product refining module is used to separate the liquid phase stream into the product stream and the return stream; An energy integration module is used to recover the heat released by the reaction and convert it into the mechanical energy and cooling required within the system. The discharge port of the raw material processing module is connected to the inlet of the multi-stage reaction module, the discharge port of the multi-stage reaction module is connected to the inlet of the gas-liquid separation module, the gas phase outlet of the gas-liquid separation module is connected to the inlet of the circulation booster module, the outlet of the circulation booster module is connected to the reflux inlet of the raw material processing module, the liquid phase outlet of the gas-liquid separation module is connected to the inlet of the product refining module, and the reflux outlet of the product refining module is connected to the reflux inlet of the raw material processing module. The energy integration module has an energy transfer coupling relationship with the multi-stage reaction module, the circulation booster module, and the product refining module, respectively. The above connections constitute a continuous closed-loop system in which the material circulation path and the energy circulation path are nested.

[0020] Furthermore, the inlet temperature regulation function of the first reaction zone is achieved by injecting a circulating medium with a temperature lower than that of the reaction stream into the feed stream, so as to control the inlet temperature of the catalyst bed within a set range (e.g., 180℃±2℃) and reduce the temperature rise of the reaction zone caused by the exothermic reaction to a predetermined level (e.g., ≤25℃); a resistance monitoring function is provided at the outlet of the first reaction zone to feed back the bed status signal to the system control terminal.

[0021] Furthermore, the interstage feeding and enhanced mixing function of the second reaction zone includes: receiving unreacted streams from the first reaction zone and injecting supplementary preheated alcohol vapor and cooling medium to achieve component and temperature regulation; simultaneously, applying a supersonic jet effect (Mach number > 1.2) to the mixed stream, causing the supplementary liquid to be torn into micro-scale droplets and instantly vaporized completely in the alternating flow field of shock waves and expansion waves, and the adiabatic compression temperature rise caused by the shock wave serves as an internal heat source for raising the temperature of the supplementary stream to the reaction activation energy; the stream after enhanced mixing enters the second reaction zone for deep conversion, and the temperature rise of this reaction zone is limited to below a predetermined level; the output of the second reaction zone merges with the unreacted material of the first reaction zone and enters the third reaction zone.

[0022] Furthermore, the constant temperature control function of the third reaction zone is achieved by adjusting the heat exchange rate between the reaction zone and the external heat medium, maintaining the reaction temperature near the set point; the third reaction zone also has an adsorption filtration function to intercept impurities entrained in the upstream stream; each of the three reaction zones is equipped with on / off control and pressure release functions, and the interstage pressure drop design value is, for example, 0.05 MPa; the outlet of the third reaction zone is equipped with a composition monitoring function to obtain the content information of target components and by-products in the product in real time and transmit this information to the system control terminal to adjust the feed rate of the pre-stage and the injection rate of the cooling medium.

[0023] Furthermore, the raw material processing module includes pressurization, metering, two-stage heat exchange, and evaporation functions. Liquid ammonia and alcohols are pressurized to, for example, 3.0-3.5 MPa via the pressurization function, then metered (with a control accuracy of, for example, ±0.2%) and transported into the first stage of the two-stage heat exchange function. They are preheated using the sensible heat of the high-temperature reaction products from the third reaction zone. The preheated liquid then enters the evaporation function and is converted into vapor under pressure. This vapor enters the second stage of the two-stage heat exchange function and mixes with the reflux gas from the circulating pressurization module to form a homogeneous reaction mixture with an adjustable ammonia-to-alcohol molar ratio in the range of 4:1 to 6:1, which is then sent to the first reaction zone.

[0024] Furthermore, the energy integration module includes a three-stage heat utilization function: the first-stage heat utilization function receives the high-temperature reaction product stream from the third reaction zone, transfers its heat to the working medium to generate low-pressure steam, and at the same time, the temperature of the reaction product drops to the first intermediate temperature; the second-stage heat utilization function uses the reaction product at the first intermediate temperature to preheat the liquid ammonia and alcohols entering the raw material processing module, so that the reaction product is further reduced to the second intermediate temperature; the third-stage heat utilization function cools the reaction product at the second intermediate temperature to the target temperature with a cooling medium and then sends it to the gas-liquid separation module; the total thermal efficiency of the three-stage heat utilization is ≥92%, and part of the low-pressure steam produced is used for heating the evaporation function, part is used for reboiling heating the product refining module, and all the steam condensate is returned to the heat medium circulation in the third reaction zone.

[0025] Furthermore, the gas-liquid separation module includes a high-pressure separation function and an ultrasonic coalescence demisting function. The high-pressure separation function is used to separate the cooled reaction products into gaseous and liquid phases under high pressure. The ultrasonic coalescence demisting function is located on the outlet channel of the gas phase. By applying a traveling wave sound field, the fine droplets entrained in the gas phase migrate, collide, and coalesce into larger droplets under the action of sound radiation force, and then naturally settle back to the high-pressure separation zone. The gas phase after demisting enters the enrichment function, selectively discharging some inert gases to maintain the stability of the partial pressure of the active atmosphere in the system. The gas phase after enriching the active components enters the circulation pressurization module to be pressurized to the threshold and then returned to the raw material processing module, so that the total recycling rate of ammonia is ≥99.2%.

[0026] Furthermore, the liquid phase stream outlet of the gas-liquid separation module is connected to a hydraulic expansion functional unit. There is a direct mechanical work transmission coupling relationship between the hydraulic expansion functional unit and the circulating booster module. The high-pressure liquid phase stream from the high-pressure separation function enters the hydraulic expansion functional unit, outputs mechanical work through the depressurization process, and provides part of the driving power for the circulating booster module. At the same time, the temperature of the liquid phase stream is significantly reduced (down to -15℃ to -20℃) after isentropic expansion. This low-temperature stream is introduced into the top condensation function of the product refining module as the only cold source, completely replacing the external refrigeration supply. The model for the work done and temperature drop during the isentropic expansion process is as follows: ; in, The output shaft power, The mass flow rate of the liquid stream. This is the inlet liquid phase enthalpy. The isentropic efficiency can be taken as 0.75-0.82. and The inlet pressure (3.0 MPa) and outlet pressure (0.5 MPa) are respectively. The equivalent adiabatic index of the liquid. For the actual temperature drop, The inlet temperature is 313K.

[0027] Furthermore, the product refining module receives the liquid phase stream after pressure and temperature reduction by the hydraulic expansion functional unit, and separates it into a light component vapor stream and a heavy component liquid stream within the refining function. The light component vapor stream is condensed by the top condensation function (using the low-temperature stream as a cold source) and then sent to the reflux separation function. The reflux phase rich in unreacted substances is completely returned to the inlet of the raw material processing module, achieving a closed-loop liquid phase with zero discharge of unreacted substances. The heavy component liquid stream is sent out of the system as the target product with a purity of ≥99.5%. The low-pressure steam generated by the energy integration module is supplied to the evaporation function of the raw material processing module on one side and to the reboiling heating function on the other side. All the steam condensate is returned to the heat medium system of the third reaction zone, forming a closed-loop heat medium cycle.

[0028] Furthermore, it also includes a microwave energy input module. When the resistance of any reaction zone reaches a set trigger value (e.g., 150% of the design value), the system control terminal automatically reduces the feed load of that reaction zone and isolates it from the main process through a bypass. Then, it starts microwave energy input for in-situ regeneration. The microwave frequency is selected according to the difference in dielectric properties between the carbon deposits and the catalytically active materials in the reaction zone (supporting dual-frequency switching between 2.45GHz and 915GHz). This allows the carbon deposits to preferentially absorb microwave energy and heat up to the vaporization temperature (600-700℃) for removal. At the same time, the temperature of the catalytically active material is maintained at a temperature far below its sintering temperature. The regeneration cycle is shortened to 6-8 hours. After completion, it switches back to the main process to achieve alternating regeneration and continuous operation. The microwave selective heating power calculation model is as follows: ; in, The microwave power absorbed by the object being heated. The operating frequency is microwave (2.45GHz or 915GHz). The vacuum permittivity, The effective dielectric loss factor of the heated object (12-18 for carbon deposits, 0.6-0.8 for catalysts). Let be the root-mean-square electric field strength inside the cavity. The catalyst bed volume; the system adjusts... and carbon deposit area For the catalytically active material region 80-120 times; Energy closed-loop efficiency is expressed as: ; in, For global energy efficiency, The increase in chemical energy carried by the target product. The heat is converted from the mechanical work recovered by hydraulic expansion. To calculate the calorific value of the refrigeration capacity for isentropic expansion, The sum of physical and chemical heat introduced by fresh raw materials. This is the heat equivalent to the net electrical power consumed by the circulating booster module after deducting the recovered power. The calorific value is calculated for the electrical energy consumed in microwave regeneration. It accounts for 40% of the total energy consumption of the cycle booster module. The top condenser of the refining module consumes zero external cooling energy. Power is supplied by low-pressure steam reforming, a byproduct of the energy integration module, ultimately ≥0.92; The raw material processing module, multi-stage reaction module, gas-liquid separation module, product refining module, circulating pressurization module and energy integration module are connected by controlled on / off logistics channels and energy transfer channels to form a fully continuous closed-loop production system of "raw material vaporization input → multi-stage reaction conversion → high-pressure gas-liquid separation → hydraulic expansion power generation and self-cooling → refining separation and full return of unreacted materials → gas phase pressurization and reuse → heat cascade matching → microwave-assisted alternating regeneration".

[0029] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0030] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A multi-stage fixed-bed gas-phase amination continuous reaction system, characterized in that, Includes the following modules: The raw material processing module is used to pressurize liquid ammonia and alcohols and convert them into a gaseous state. The multi-stage reaction module consists of a first reaction zone, a second reaction zone, and a third reaction zone connected in series. The first reaction zone is equipped with an inlet temperature regulation function, the second reaction zone is equipped with an interstage feeding and enhanced mixing function, and the third reaction zone is equipped with a constant temperature control function. The gas-liquid separation module is used to separate reaction products into gaseous and liquid streams. A circulating pressurization module is used to pressurize the gaseous stream and send it back to the raw material processing module; The product refining module is used to separate the liquid phase stream into product stream and return stream; An energy integration module is used to recover the heat released by the reaction and convert it into the mechanical energy and cooling required within the system.

2. The multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 1, characterized in that, The inlet temperature regulation function of the first reaction zone is achieved by injecting a circulating medium with a temperature lower than that of the reaction stream into the feed stream, so as to control the inlet temperature of the catalyst bed within the set range and reduce the temperature rise of the reaction zone caused by the exothermic reaction to a predetermined level; a resistance monitoring function is provided at the outlet of the first reaction zone to feed back the bed status signal to the system control terminal.

3. The multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 2, characterized in that, The interstage feeding and enhanced mixing function of the second reaction zone includes: receiving unreacted streams from the first reaction zone and injecting supplementary preheated alcohol vapor and cooling medium to achieve component and temperature regulation; simultaneously, applying a supersonic jet to the mixture stream, causing the supplementary liquid to be torn into micro-scale droplets and instantly vaporized completely in an alternating flow field of shock waves and expansion waves, with the adiabatic compression temperature rise caused by the shock wave serving as an internal heat source to raise the temperature of the supplementary stream to the reaction activation energy; the enhanced mixed stream enters the second reaction zone for deep conversion, where the temperature rise is limited to below a predetermined level; the output of the second reaction zone merges with the unreacted material from the first reaction zone and enters the third reaction zone.

4. The multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 3, characterized in that, The constant temperature control function of the third reaction zone is achieved by adjusting the heat exchange rate between the reaction zone and the external heat medium to maintain the reaction temperature near the set point. The third reaction zone also has an adsorption and filtration function to intercept impurities carried in the upstream material. The three reaction zones are equipped with on / off control and pressure release functions, and the interstage pressure drop design value is, for example, 0.05 MPa. The outlet of the third reaction zone is equipped with a composition monitoring function to obtain the content information of target components and by-products in the product in real time and transmit the information to the system control terminal to adjust the feed rate and cooling medium injection rate.

5. A multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 4, characterized in that, The raw material processing module includes a pressurization function, a metering function, a two-stage heat exchange function, and an evaporation function. Liquid ammonia and alcohols are pressurized to, for example, 3.0-3.5 MPa by the pressurization function, and then transported by the metering function into the first stage of the two-stage heat exchange function. They are preheated by the sensible heat of the high-temperature reaction products from the third reaction zone. The preheated liquid then enters the evaporation function and is converted into vapor under pressure. This vapor enters the second stage of the two-stage heat exchange function and mixes with the reflux gas from the circulating pressurization module to form a homogeneous reaction mixture with an adjustable ammonia-to-alcohol molar ratio in the range of 4:1 to 6:1, which is then sent to the first reaction zone.

6. The multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 1, characterized in that, The energy integration module includes a three-stage heat utilization function: the first-stage heat utilization function receives the high-temperature reaction product stream from the third reaction zone, transfers its heat to the working medium to generate low-pressure steam, and at the same time, the temperature of the reaction product drops to a first intermediate temperature; the second-stage heat utilization function uses the reaction product at the first intermediate temperature to preheat the liquid ammonia and alcohols entering the raw material processing module, so that the reaction product is further reduced to a second intermediate temperature; the third-stage heat utilization function cools the reaction product at the second intermediate temperature to the target temperature with a cooling medium and then sends it to the gas-liquid separation module.

7. A multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 6, characterized in that, The gas-liquid separation module includes a high-pressure separation function and an ultrasonic coalescence demisting function. The high-pressure separation function is used to separate the cooled reaction products into a gas phase stream and a liquid phase stream under high pressure. The ultrasonic coalescence demisting function is set on the outlet channel of the gas phase stream. By applying a traveling wave sound field, the fine liquid droplets entrained in the gas phase migrate, collide, and coalesce into larger droplets under the action of sound radiation force, and then naturally settle back to the high-pressure separation zone. The gas phase stream after demisting enters the enrichment function, selectively discharges some inert gas to maintain the stability of the partial pressure of the active atmosphere in the system, and the gas phase stream enriched with active components enters the circulation pressurization module to be pressurized to the threshold and then returned to the raw material processing module.

8. A multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 7, characterized in that, The liquid phase stream outlet of the gas-liquid separation module is connected to a hydraulic expansion functional unit. There is a direct mechanical work transmission coupling relationship between the hydraulic expansion functional unit and the circulating pressurization module. The high-pressure liquid phase stream from the high-pressure separation function enters the hydraulic expansion functional unit, outputs mechanical work through the depressurization process, and provides part of the driving power for the circulating pressurization module. At the same time, the temperature of the liquid phase stream is significantly reduced after isentropic expansion. This low-temperature stream is introduced into the top condensation function of the product refining module as the only cold source, completely replacing the external refrigeration supply. The model for the work done and temperature drop during the isentropic expansion process is as follows: in, The output shaft power, The mass flow rate of the liquid stream. This is the inlet liquid phase enthalpy. For isentropic efficiency, and These are the inlet pressure and the outlet pressure, respectively. The equivalent adiabatic index of the liquid. For the actual temperature drop, This refers to the inlet temperature.

9. A multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 8, characterized in that, The product refining module receives the liquid phase stream after it has been depressurized and cooled by the hydraulic expansion function unit, and separates it into a light component vapor stream and a heavy component liquid stream within the refining function. The light component vapor stream is condensed by the top condensation function and then sent to the reflux separation function. The reflux phase rich in unreacted substances is completely returned to the inlet of the raw material processing module, realizing a closed-loop liquid phase with zero discharge of unreacted substances.

10. A multi-stage fixed-bed gas-phase amination continuous reaction system according to claim 9, characterized in that, It also includes a microwave energy input module. When the resistance of any reaction zone reaches the set trigger value, the system control terminal automatically reduces the feed load of the reaction zone and isolates it from the main process through a bypass. Then, the microwave energy input is started for in-situ regeneration. The microwave frequency is selected based on the difference in dielectric properties between the carbon deposits and the catalytically active materials in the reaction zone, so that the carbon deposits preferentially absorb microwave energy and are removed by heating up to the vaporization temperature. At the same time, the temperature of the catalytically active material is maintained at a temperature much lower than its sintering temperature, shortening the regeneration cycle to 6-8 hours. After completion, the process is switched back to the main process to achieve alternating regeneration and continuous operation. The microwave selective heating power calculation model is as follows: ； in, The microwave power absorbed by the object being heated. This is the microwave operating frequency. The vacuum permittivity, The effective dielectric loss factor of the object being heated. Let be the root-mean-square electric field strength inside the cavity. This refers to the catalyst bed volume; Energy closed-loop efficiency is expressed as: ； in, For global energy efficiency, The increase in chemical energy carried by the target product. The heat is converted from the mechanical work recovered by hydraulic expansion. To calculate the calorific value of the refrigeration capacity for isentropic expansion, The sum of physical and chemical heat introduced by fresh raw materials. This is the heat equivalent to the net electrical power consumed by the circulating booster module after deducting the recovered power. The calorific value is calculated based on the electrical energy consumed by microwave regeneration.

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