Process system and method for producing acrylonitrile
By optimizing the process system of propylene ammoxidation, and adopting reasonable layout and catalyst management, the problems of low conversion rate and high energy consumption were solved, achieving efficient and low-cost acrylonitrile production, and ensuring the safety and environmental friendliness of the system.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SHANGHAI REZEL KEHUA ENG DESIGN CO LTD
- Filing Date
- 2025-04-23
- Publication Date
- 2026-07-23
AI Technical Summary
The existing propylene ammoxidation process for producing acrylonitrile has low conversion rate, high energy consumption, and the catalyst is carried downstream, leading to unstable downstream operation. The catalyst replacement process in the reactor is also complex.
A process system including an ammonia-propylene reactor, a heating device, an ammonia-propylene mixer, a cyclone separator, and a filter was designed. The reaction conversion rate and product yield were improved through reasonable layout and catalyst management. The heat exchanger and superheater with external heat extraction and back-mixing were used to optimize energy consumption. The superheated steam generated by the incinerator was used to drive the air compressor to achieve flexible replacement and replenishment of the catalyst.
It improves reaction conversion and product yield, reduces energy consumption and operating costs, ensures system safety and environmental friendliness, and simplifies catalyst operation.
Smart Images
Figure CN2025090597_23072026_PF_FP_ABST
Abstract
Description
A process system and method for producing acrylonitrile Technical Field
[0001] This invention relates to the field of acrylonitrile production technology, and more particularly to a process system and method for producing acrylonitrile. Background Technology
[0002] Acrylonitrile is the main raw material for producing polyacrylonitrile fiber (acrylic fiber). Acrylic fiber is known for its excellent properties such as softness, warmth, and light resistance. In addition, the demand for high-performance fibers in special fields such as industrial filtration and outdoor products will further promote the application of acrylonitrile in the field of synthetic fibers. Acrylonitrile is also copolymerized with butadiene to produce nitrile rubber, which has good oil resistance, abrasion resistance, and heat resistance, and is widely used in products such as seals and conveyor belts in the automotive, aerospace, and petrochemical industries. As a key component in the production of ABS resin (acrylonitrile-butadiene-styrene copolymer), ABS resin has high strength, high toughness, and good processing performance, and is widely used in many fields such as electronics, automotive parts, and building materials. Acrylonitrile is also used to produce a variety of fine chemical products, such as water-resistant agents, adhesives, coatings, and carbon fibers.
[0003] Acrylonitrile was first produced industrially in the 1840s, using hydrogen cyanide reacting with ethylene oxide or acetylene. In 1960, Sohio Corporation in the United States pioneered and developed the propylene ammoxidation process (Sohio process), which was quickly adopted. After years of development, the production technology of acrylonitrile has become increasingly mature and perfected. Today, more than 95% of the world's acrylonitrile is produced using the Sohio process.
[0004] In recent years, the main technology for acrylonitrile production in China has been the propylene ammoxidation process, which accounts for over 90% of the global market share. The propylene ammoxidation process uses propylene and ammonia as raw materials to produce acrylonitrile, with acetonitrile and hydrogen cyanide as byproducts. This technology features readily available raw materials, simple processes, stable operation, and convenient product refining. However, current drawbacks include low conversion rates, high energy consumption, catalyst carryover to downstream processes leading to instability, and complex catalyst replacement processes in the reactor. Summary of the Invention
[0005] This invention aims to solve the problems of low conversion rate, high energy consumption, catalyst carryover to downstream processes leading to unstable downstream operation, and complex catalyst replacement process in the reactor in the current ammoxidation method for producing acrylonitrile, and provides a process system and method for producing acrylonitrile.
[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows:
[0007] A process system for producing acrylonitrile includes an ammonia-propylene reactor connected to a heating device and an ammonia-propylene mixer, the heating device being connected to an air compressor; the ammonia-propylene mixer being connected to a propylene superheater and an ammonia superheater, the propylene superheater being connected to a propylene evaporator, and the ammonia superheater being connected to an ammonia evaporator.
[0008] Specifically, the heating device includes, but is not limited to, a heating furnace.
[0009] Furthermore, the air compressor is equipped with an air filter, which can filter out impurities in the air, prevent contamination of the catalyst, and indirectly improve the reaction conversion rate and product yield.
[0010] Furthermore, the ammonia-propylene reactor is equipped with a heat exchanger connected to an air compressor. The heat exchanger adopts an external heat exchange and back-mixing method, and the heat load of the ammonia-propylene reactor is adjusted by compressed air. This method is convenient to operate, easy to control, and has a significant heat exchange effect.
[0011] Furthermore, the heat exchanger is connected to a fresh catalyst tank and a spent catalyst tank.
[0012] Furthermore, the heat exchanger is connected to a heat exchange steam drum, the heat exchange steam drum is connected to a superheater, and the top of the heat exchange steam drum is connected to an incinerator.
[0013] Furthermore, the ammonia-propylene reactor is equipped with a primary cyclone separator and a secondary cyclone separator, with the secondary cyclone separator connected to the primary cyclone separator, and the efficiency of the cyclone catalyst is 99%.
[0014] Furthermore, the ammonia-propylene reactor is connected to a filter and a catalyst collection tank, with the bottom of the filter connected to the catalyst collection tank, which in turn is connected to a fresh catalyst tank and a spent catalyst tank.
[0015] Specifically, the filtered catalyst is sampled and analyzed. If the performance is stable, the filtered catalyst is added to the ammonia-propylene reactor through the catalyst collection tank. If the catalyst performance is poor, it is unloaded into the waste catalyst tank. The operation is flexible and easy to use. When adding catalyst to the ammonia-propylene reactor, fresh catalyst is added to the ammonia-propylene reactor through the catalyst collection tank.
[0016] Furthermore, a superheater is connected to the top of the filter, and the superheater is connected to the absorption tower.
[0017] Specifically, lowering the temperature of the reaction products by using a superheater helps the downstream absorption tower absorb acrylonitrile products.
[0018] Furthermore, the top of the absorption tower is connected to an incinerator, which is equipped with an incinerator steam drum.
[0019] The present invention also provides a method for producing acrylonitrile, comprising the following steps:
[0020] Step 1: Propylene and ammonia are pumped into the propylene evaporator and ammonia evaporator respectively to vaporize propylene and ammonia. The vaporized propylene and ammonia are then passed through a heater and superheated before entering the ammonia-propylene mixer for uniform mixing. After mixing, the mixture enters the ammonia-propylene reactor.
[0021] Step 2: After the raw material air is compressed by the air compressor, the compressed air enters the bottom of the ammonia-propylene reactor through the heating device and mixes with propylene and ammonia. The mixed gas fluidizes the catalyst bed and reacts simultaneously.
[0022] The present invention has the following beneficial effects:
[0023] 1. This invention adopts a rationally laid-out process system for producing acrylonitrile, which has a simple structure, small footprint, and low investment cost. The raw materials, liquid propylene and ammonia, are pumped from the liquid raw material tank area into the propylene and ammonia evaporators. After being superheated by the heat exchanger, the vaporized propylene and ammonia gases enter the ammonia-propylene mixer for uniform mixing. After mixing, they enter the ammonia-propylene reactor. On the other hand, the raw material air is taken from the atmosphere. After being filtered, the air enters the air compressor. The air compressed by the air compressor is started and enters the bottom of the ammonia-propylene reactor through the heating device, where it is mixed with propylene and ammonia.
[0024] 2. The catalyst carried by the reaction product of this invention is filtered through a filter and then sent to the ammonia-propylene reactor through a catalyst collection tank. If the catalyst activity in the ammonia-propylene reactor decreases or there is too much fine powder, the catalyst in the catalyst collection tank can be unloaded to the waste catalyst tank and fresh catalyst can be added to the ammonia-propylene reactor. The replacement and replenishment of catalysts are flexible and easy to use, ensuring the reaction conversion rate and product yield. The tail gas of the acrylonitrile production process system is incinerated, which is environmentally friendly.
[0025] 3. In this invention, deoxygenated water enters the superheater for heating before entering the heat extraction steam drum, simultaneously lowering the temperature of the reaction products and improving heat utilization. Hot water in the heat extraction steam drum enters the heat extractor through pipes. In addition, 4.0 MPa saturated steam is generated by extracting the reaction heat from the ammonia-propylene reactor. This 4.0 MPa saturated steam enters the heat extraction steam drum through pipes. The saturated steam from the heat extraction steam drum merges with the saturated steam from the incinerator steam drum through pipes and enters the superheating section of the incinerator for superheating, ultimately producing 4.0 MPa superheated steam. This 4.0 MPa superheated steam is used to drive the air compressor 8. The system produces superheated steam as a byproduct, resulting in low energy consumption and low overall operating costs.
[0026] 4. The incinerator of this invention is safe, reliable, environmentally friendly, produces steam, and has low operating costs. The ammonia-propylene reactor includes a cyclone separator to separate the catalyst carried in the products; a filter to filter the catalyst carried in the reaction products; an air filter to filter impurities from the air, preventing catalyst contamination; an ammonia-propylene mixer to fully mix propylene and ammonia, ensuring uniform feed mixing and improving reaction conversion and yield; a catalyst collection tank to collect filtered catalyst, replenishing it to the ammonia-propylene reactor or directly discharging it to a waste catalyst tank, improving catalyst utilization efficiency and offering convenient operation; a heat exchanger using an external heat exchange and back-mixing method, offering convenient operation, easy control, safety, high heat utilization, steam production, low energy consumption, and low operating costs. The heat exchanger can also serve as a catalyst replacement and replenishment transfer device for the reactor, offering convenient and flexible operation; a superheater allows deoxygenated water to pass through, lowering the temperature of the reaction products while raising the temperature of the deoxygenated water, saving energy, reducing consumption, and improving thermal efficiency; and separate evaporators and superheaters for propylene and ammonia, effectively increasing feed temperature without interference, ensuring easy operation and control. Attached Figure Description
[0027] Figure 1 is a flowchart of Embodiment 1 provided by the present invention;
[0028] Figure 2 is a flowchart of Embodiment 2 provided by the present invention;
[0029] The attached diagram shows the following components and their corresponding names: 1-Ammonia-propylene reactor; 2-Propylene evaporator; 3-Propylene superheater; 4-Ammonia evaporator; 5-Ammonia superheater; 6-Ammonia-propylene mixer; 7-Heater; 8-Air compressor; 9-Heating device; 10-Filter; 11-Catalyst collection tank; 12-Fresh catalyst tank; 13-Waste catalyst tank; 14-Superheater; 15-Absorber tower; 16-Heater steam drum; 17-Incinerator; 18-Incinerator steam drum; 101-First-stage cyclone separator; 102-Second-stage cyclone separator; 103-Air filter. Detailed Implementation
[0030] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.
[0031] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0032] Example 1
[0033] As shown in Figure 1, this embodiment provides a process system for producing acrylonitrile, including an ammonia-propylene reactor 1. The bottom of the ammonia-propylene reactor 1 is connected to a heating device 9, which is connected to an air compressor 8. An air filter 103 is installed at the inlet of the air compressor 8. Before entering the air compressor 8, the air passes through the air filter 103 to filter out impurities carried in the air, thus not affecting the reaction effect. The filtration effect is obvious. When the heating device 9 is started, it can increase the temperature of the compressed air and shorten the start-up time. During normal production, it can be set up as a cross-line or as a compressed air channel. In the event of shutdown or accident, it is used to burn off the catalyst to maintain the temperature of the ammonia-propylene reactor 1 and to cooperate with the unloading of the catalyst so that the unloaded catalyst is in a regenerated state.
[0034] In this embodiment, the ammonia-propylene reactor 1 is connected to an ammonia-propylene mixer 6 at the bottom. The ammonia-propylene mixer 6 is connected to a propylene superheater 3 and an ammonia superheater 5. The propylene superheater 3 is connected to a propylene evaporator 2, and the ammonia superheater 5 is connected to an ammonia evaporator 4. The raw material liquid propylene is pumped from the propylene spherical tank in the liquid raw material tank area into the propylene evaporator 2, and the propylene is controlled to vaporize at 0°C. The vaporized propylene gas is superheated by the propylene superheater 3. The raw material liquid ammonia is pumped from the ammonia spherical tank in the liquid raw material tank area into the ammonia evaporator 4, and the ammonia is controlled to vaporize at 7°C. The vaporized ammonia is superheated by the ammonia superheater 5, and then mixed evenly with the superheated propylene in the ammonia-propylene mixer 6 before entering the ammonia-propylene reactor 1.
[0035] In this embodiment, a heat exchanger 7 is installed outside the ammonia-propylene reactor 1. The heat exchanger 7 is a back-mixing type and is connected to an air compressor 8. The heat load of the ammonia-propylene reactor 1 is adjusted by compressed air. The two streams of fluidized compressed air provide significant heat exchange effect, are easy to control, and are convenient to operate. The heat exchanger 7 is connected to a fresh catalyst tank 12 and a spent catalyst tank 13. The connection of the heat exchanger 7 to the fresh catalyst tank: If the ammonia-propylene reactor 1 lacks catalyst or has insufficient catalyst, the catalyst can be replenished to the heat exchanger through the fresh catalyst tank. The catalyst storage capacity of the heat exchanger 7 is fixed, and the replenished catalyst (equivalent to excess catalyst) will directly enter the ammonia-propylene reactor 1 to supply the reaction in the ammonia-propylene reactor 1. The connection of the heat exchanger 7 to the spent catalyst tank: The temperature of the ammonia-propylene reactor 1 is generally relatively high. During the catalyst unloading process, the temperature of the catalyst unloading pipeline may rise, even exceeding the design limit. In order to avoid damage to the catalyst pipeline and equipment, the catalyst can be unloaded from the heat exchanger 7.
[0036] In this embodiment, the ammonia-propylene reactor 1 is equipped with a primary cyclone separator 101 and a secondary cyclone separator 102. The efficiency of the cyclone separator for catalyst separation is 99%. A filter 10 is connected to the top of the ammonia-propylene reactor 1, and a superheater 14 and an absorption tower 15 are connected to the top of the filter 10 in sequence. The number of filters 10 can be 3 to 6 depending on the needs of the device, with a catalyst filtration efficiency of over 99%. The combination of the cyclone separator and the filter results in a total efficiency of over 99.99%, indicating good catalyst removal. The ammonia-propylene reactor 1 is connected to the filter 10 and the catalyst collection tank 11. The bottom of the filter 10 is connected to the catalyst collection tank 11. The catalyst collection tank 11 is connected to the fresh catalyst tank 12 and the waste catalyst tank 13. The catalyst in the collection tank 11 is sampled and analyzed. The direction of the catalyst in the collection tank 11 is determined according to the analysis results. When the catalyst activity is high, the catalyst in the collection tank 11 is directly fed into the ammonia-propylene reactor 1. When the activity is low or there is a lot of fine powder, the catalyst in the collection tank 11 is directly discharged to the waste catalyst tank 13. When the amount of catalyst in the ammonia-propylene reactor 1 is low, fresh catalyst can be added to the catalyst collection tank 11 through the fresh catalyst tank 12. Finally, the fresh catalyst in the collection tank 11 can enter the ammonia-propylene reactor 1 through the pipeline.
[0037] Example 2
[0038] As shown in Figure 2, the upper end of the superheater 14 is connected to the heat extraction steam drum 16, and the heat extraction steam drum 16 is connected to the heat extractor 7; the lower end of the superheater 14 is connected to the absorption tower 15, and the top of the absorption tower 15 is connected to the incinerator 17, which is equipped with an incinerator steam drum 18; the deoxygenated water enters the superheater 14 for heating and then enters the heat extraction steam drum 16, which simultaneously lowers the temperature of the reaction products and improves the heat utilization rate. The hot water in the heat extraction steam drum 16 enters the heat extractor 7 through a pipeline; in addition, the reaction heat of the ammonia-propylene reactor 1 is used to produce 4.0 MPa saturated steam, which enters the heat extraction steam drum 16 through a pipeline. The saturated steam in the heat extraction steam drum 16 merges with the saturated steam in the incinerator steam drum 18 through a pipeline and enters the superheating section of the incinerator 17 for superheating, ultimately producing 4.0 MPa superheated steam, which is used to drive the air compressor 8.
[0039] In this embodiment, the exhaust gas from the absorption tower 15 enters the incinerator 17 for combustion. The incinerator 17 is equipped with an evaporation section, a superheating section, and a heating section. The deoxygenated water enters the heating section and is heated before entering the incinerator steam drum 18. The hot water from the incinerator steam drum 18 enters the evaporation section of the incinerator 17 to produce saturated steam. The saturated steam enters the incinerator steam drum 18 through a pipeline. The saturated steam from the incinerator steam drum 18 and the saturated steam from the heat extraction steam drum 16 merge and enter the superheating section of the incinerator 17 for superheating, ultimately producing superheated steam at 4.0 MPa.
[0040] The acrylonitrile production process system provided in this embodiment has a simple structure, small footprint, low investment cost, is safe and reliable, environmentally friendly, flexible in operation, produces steam, has high heat utilization rate, low energy consumption, and low operating cost of the production process.
[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
[0042] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.
Claims
1. A process system for producing acrylonitrile, characterized in that, It includes an ammonia-propylene reactor (1), which is connected to a heating device (9) and an ammonia-propylene mixer (6), and the heating device (9) is connected to an air compressor (8); the ammonia-propylene mixer (6) is connected to a propylene superheater (3) and an ammonia superheater (5), the propylene superheater (3) is connected to a propylene evaporator (2), and the ammonia superheater (5) is connected to an ammonia evaporator (4).
2. The process system for producing acrylonitrile according to claim 1, characterized in that, The air compressor (8) is equipped with an air filter (103).
3. The process system for producing acrylonitrile according to claim 1, characterized in that, The ammonia-propylene reactor (1) is equipped with a heat exchanger (7), which is connected to an air compressor (8).
4. The process system for producing acrylonitrile according to claim 3, characterized in that, The heat exchanger (7) is connected to the fresh catalyst tank (12) and the waste catalyst tank (13).
5. The process system for producing acrylonitrile according to claim 3, characterized in that, The heat exchanger (7) is connected to the heat exchange steam drum (16), the heat exchange steam drum (16) is connected to the superheater (14), and the top of the heat exchange steam drum (16) is connected to the incinerator (17).
6. The process system for producing acrylonitrile according to claim 1, characterized in that, The ammonia-propylene reactor (1) is equipped with a primary cyclone separator (101) and a secondary cyclone separator (102), with the secondary cyclone separator (102) connected to the primary cyclone separator (101).
7. The process system for producing acrylonitrile according to claim 1, characterized in that, The ammonia-propylene reactor (1) is connected to a filter (10) and a catalyst collection tank (11). The bottom of the filter (10) is connected to the catalyst collection tank (11), and the catalyst collection tank (11) is connected to a fresh catalyst tank (12) and a waste catalyst tank (13).
8. The process system for producing acrylonitrile according to claim 7, characterized in that, The filter (10) is connected to a superheater (14) at the top, and the superheater (14) is connected to an absorption tower (15).
9. The process system for producing acrylonitrile according to claim 8, characterized in that, The top of the absorption tower (15) is connected to the incinerator (17), and the incinerator (17) is equipped with an incinerator steam drum (18).
10. A method for producing acrylonitrile using a process system according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Propylene and ammonia are pumped into the propylene evaporator and ammonia evaporator respectively to vaporize propylene and ammonia. The vaporized propylene and ammonia are then passed through a heater and superheated before entering the ammonia-propylene mixer for uniform mixing. After mixing, the mixture enters the ammonia-propylene reactor. Step 2: After the raw material air is compressed by the air compressor, the compressed air enters the bottom of the ammonia-propylene reactor through the heating device and mixes with propylene and ammonia. The mixed gas fluidizes the catalyst bed and reacts simultaneously.