A mixed acid system for an acrylonitrile plant

Abstract

This invention discloses a mixing system for an acrylonitrile plant, comprising a circulation pipeline and a mixing component. The circulation pipeline includes a first layer and a second layer arranged coaxially, with the first layer fitted over the second layer. The mixing component has a second channel and includes a third layer and two fourth layers arranged coaxially, with the two fourth layers fitted over the inner and outer sides of the third layer, respectively. During mixing operations, the second layer within the first layer provides stable corrosion protection, preventing sulfuric acid from corroding the pipeline material. The fourth layers provide reliable protection for the third layer, enhancing the durability and safety of the mixing component. When sulfuric acid is added to the first channel through the second channel, a more stable barrier effect is achieved, realizing effective mixing of sulfuric acid and quench tower circulating liquid. Simultaneously, it provides good corrosion protection, reduces leakage risk, and achieves a more convenient and stable mixing process.

Description

Technical Field

[0001] This application relates to the field of acrylonitrile technology, and in particular to a mixed acid system for acrylonitrile plants. Background Technology

[0002] The information provided in this section is for the purpose of generally presenting the background of this disclosure. To the extent described in this section, the work of the currently named inventors and aspects of the description that may not constitute prior art at the time of filing are neither explicitly nor implicitly considered to be prior art of this disclosure.

[0003] In the process of ammoxidizing propylene to acrylonitrile, sulfuric acid is used to neutralize unreacted ammonia in the reactor. Currently, sulfuric acid is added to the quench tower circulating liquid via a mixer. Because the quench tower circulating liquid contains a large amount of water, the addition of sulfuric acid leads to an exothermic reaction, exacerbating corrosion and increasing the risk of material leakage. The quench tower circulating liquid also contains hazardous substances such as hydrogen cyanide, acrylonitrile, and its polymers; leaks could lead to shutdowns, production stoppages, and even personnel casualties. Therefore, ensuring the long-term, safe, and reliable operation of the plant hinges on resolving corrosion and leakage issues during the sulfuric acid neutralization process. Summary of the Invention

[0004] In view of the deficiencies in the prior art, this application provides a mixed acid system for an acrylonitrile plant to solve the problems of poor reliability and low safety in the sulfuric acid neutralization process in the prior art.

[0005] The above-mentioned objectives of this application are mainly achieved through the following technical solutions:

[0006] A mixed acid system for an acrylonitrile plant, the mixed acid system comprising:

[0007] A circulation pipeline is used to connect to the circulation pipeline of the quench tower. The circulation pipeline has a first channel for the flow of circulating liquid and an installation hole. The circulation pipeline includes a first layer and a second layer arranged coaxially, with the first layer fitted over the second layer.

[0008] The mixing component has a second channel inside it, and a first opening and a second opening are respectively arranged at both ends of the second channel. The mixing component extends into the mounting hole and is fixedly connected to the circulation pipeline. The first opening is located outside the first channel, and the second opening is located inside the first channel. The mixing component includes a third layer and two fourth layers arranged coaxially. The two fourth layers are respectively fitted inside and outside the third layer.

[0009] In an optional embodiment, the first layer and the third layer are made of stainless steel, and the second layer and the fourth layer are made of polytetrafluoroethylene.

[0010] In an optional embodiment, the second layer is disposed inside the first layer by a tight-fitting process, and the fourth layer is disposed inside and outside the third layer by a tight-fitting process.

[0011] In an optional embodiment, the thickness of the fourth layer located inside the third layer is not less than 12 mm, and the thickness of the other fourth layer and the second layer is not less than 3 mm.

[0012] In an optional embodiment, the circulation pipeline is provided with a riser, the riser is fixed at the mounting hole, and the mixing component is detachably connected to the riser.

[0013] In an optional embodiment, the riser is provided with a first annular platform, the mixing component is provided with a second annular platform, the mixed acid system includes a clamping part detachably connected to the first annular platform, and the second annular platform extends between the clamping part and the first annular platform.

[0014] In an optional embodiment, the pressing part includes a third annular platform pressed on the first annular platform, and a connecting section coaxially arranged with the mixture. The connecting section includes a fifth layer and a sixth layer coaxially arranged, with the sixth layer fitted inside the fifth layer.

[0015] In an alternative embodiment, the end of the connecting segment away from the hybrid component is detachably connected to a connecting flange.

[0016] In an optional embodiment, the second opening is arranged on one side of the fourth layer, which is located inside the third layer, and the second opening is oriented toward the flow direction of the circulating liquid.

[0017] In an optional embodiment, the opening of the second opening is 10°-90°.

[0018] Compared with the prior art, the advantages of this application are:

[0019] The mixed acid system described in this application is applied to an acrylonitrile plant. The mixed acid system includes a circulation pipeline and a mixing component. The circulation pipeline is connected to the circulation pipeline of a quench tower. The circulation pipeline has a first channel for the flow of circulating liquid and an installation hole. The circulation pipeline includes a first layer and a second layer arranged coaxially, with the first layer fitted over the second layer. The mixing component has a second channel and a first opening and a second opening respectively located at both ends of the second channel. The mixing component extends into the installation hole and is fixedly connected to the circulation pipeline. The first opening is located outside the first channel. The second opening is located inside the first channel. The mixing component includes a third layer and two fourth layers arranged coaxially. The two fourth layers are respectively fitted inside and outside the third layer. During acid mixing, the second layer inside the first layer provides stable corrosion protection to prevent sulfuric acid from corroding the pipeline material. The fourth layer provides reliable protection for the third layer, enhancing the durability and safety of the mixing component. When sulfuric acid is added to the first channel through the second channel, a more stable barrier effect is obtained, achieving effective mixing of sulfuric acid and quench tower circulating liquid. At the same time, it provides good corrosion protection, reduces the risk of leakage, and achieves a more convenient and stable acid mixing purpose. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A structural view of a mixed acid system is provided for embodiments of this application;

[0022] Figure 2 A partial cross-sectional view of the hybrid component is provided for the embodiments of this application;

[0023] In the diagram: 100, circulation pipeline; 101, first channel; 102, mounting hole; 103, first layer; 104, second layer; 200, mixing component; 201, second annular platform; 202, second channel; 203, first opening; 204, second opening; 205, third layer; 206, fourth layer; 301, riser; 302, first annular platform; 400, clamping part; 401, third annular platform; 402, connecting section; 403, connecting flange; 404, fifth layer; 405, sixth layer. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the description of these embodiments is intended to aid in understanding the invention, but does not constitute a limitation thereof. The specific structural and functional details disclosed herein are merely for describing exemplary embodiments of the invention. However, the invention can be embodied in many alternative forms and should not be construed as being limited to the embodiments described herein.

[0025] like Figure 1 , Figure 2 As shown, Figure 1 A structural view of the mixed acid system is provided for embodiments of this application. Figure 2 A partial cross-sectional view of the mixing component 200 is provided for an embodiment of this application, illustrating a mixed acid system for an acrylonitrile plant, the mixed acid system comprising a circulation pipeline 100 and a mixing component 200, wherein:

[0026] like Figure 1 , Figure 2 As shown, the circulation pipeline 100 is used to connect to the circulation pipeline 100 of the quench tower. The circulation pipeline 100 is provided with a first channel 101 for the flow of circulating liquid. The circulation pipeline 100 is provided with an installation hole 102. The circulation pipeline 100 includes a first layer 103 and a second layer 104 arranged coaxially. The first layer 103 is fitted over the second layer 104.

[0027] The circulation pipe 100 is a key component connecting the quench tower circulation pipe 100. The internal design of the circulation pipe 100 includes a first channel 101 for the flow of the circulating liquid. The first channel 101 ensures smooth flow of the circulating liquid within the circulation pipe 100, thereby maintaining the continuous operation of the entire system. For ease of installation and maintenance, the circulation pipe 100 is provided with mounting holes 102, which are used to secure the mixing component 200 in a proper position, ensuring a tight fit between the mixing component 200 and the circulation pipe 100.

[0028] like Figure 1 , Figure 2 As shown, the circulation pipeline 100 adopts a coaxial arrangement of a first layer 103 and a second layer 104, wherein the first layer 103 is tightly fitted and sleeved on the outside of the second layer 104 to form double protection, which enhances the strength and corrosion resistance of the pipeline.

[0029] like Figure 1 , Figure 2As shown, the mixing component 200 has a second channel 202, and the mixing component 200 has a first opening 203 and a second opening 204 respectively arranged at both ends of the second channel 202. The mixing component 200 extends into the mounting hole 102 and is fixedly connected to the circulation pipeline 100. The first opening 203 is located outside the first channel 101, and the second opening 204 is located inside the first channel 101. The mixing component 200 includes a third layer 205 arranged coaxially and two fourth layers 206. The two fourth layers 206 are respectively fitted and sleeved on the inner and outer sides of the third layer 205.

[0030] like Figure 1 , Figure 2 As shown, the mixing component 200 has a second channel 202 inside, which is connected to the first channel 101 of the circulation pipeline 100 for the flow of sulfuric acid, ensuring that sulfuric acid can be smoothly added to the circulation liquid. The mixing component 200 has a first opening 203 and a second opening 204, which are respectively arranged at both ends of the second channel 202 for controlling the inflow and mixing of sulfuric acid.

[0031] like Figure 1 , Figure 2 As shown, the mixing component 200 extends into the mounting hole 102 and is fixedly connected to the circulation pipeline 100 to ensure stability and reliability during operation. The first opening 203 is located outside the first channel 101 to facilitate the addition of sulfuric acid; the second opening 204 is located inside the first channel 101 for mixing sulfuric acid with the circulating liquid.

[0032] The hybrid component 200 includes a third layer 205 and two fourth layers 206 arranged coaxially, which improves the strength and corrosion resistance of the hybrid component 200. The two fourth layers 206 are respectively fitted and sleeved on the inner and outer sides of the third layer 205, forming a double-layer protection, which further enhances the durability and safety of the hybrid component 200.

[0033] like Figure 1 , Figure 2 As shown, during the acid mixing process, sulfuric acid is added to the second channel 202 of the mixing component 200 through the first opening 203, and then flows into the first channel 101 through the second opening 204 to mix with the circulating liquid. The coaxial structure of the first layer 103 and the second layer 104 provides stable corrosion protection, reducing the erosion of the pipeline material by sulfuric acid.

[0034] The coaxial structure of the third layer 205 and the two fourth layers 206 provides reliable protection for the mixing component 200, ensuring its stability in highly corrosive environments. This double-layer protection effectively prevents sulfuric acid leakage, ensuring operator safety and stable equipment operation. It provides additional corrosion protection, extends equipment lifespan, and results in more uniform mixing of sulfuric acid and circulating liquid, improving neutralization efficiency.

[0035] In an optional embodiment, the mixed acid system of this application is applied to an acrylonitrile unit. The working principle of the mixed acid system is as follows: the mixed acid system includes a circulation pipeline 100 and a mixing component 200. The circulation pipeline 100 is used to connect to the circulation pipeline 100 of the quench tower. The circulation pipeline 100 has a first channel 101 for the flow of circulating liquid. The circulation pipeline 100 has a mounting hole 102. The circulation pipeline 100 includes a first layer 103 and a second layer 104 arranged coaxially. The first layer 103 is fitted over the second layer 104. The mixing component 200 has a second channel 202. The mixing component 200 has a first opening 203 and a second opening 204 respectively arranged at both ends of the second channel 202. The mixing component 200 extends into the mounting hole 102 and is fixed to the circulation pipeline 100. The mixing component 200 is fixedly connected, with the first opening 203 located outside the first channel 101 and the second opening 204 located inside the first channel 101. The mixing component 200 includes a third layer 205 and two fourth layers 206 arranged coaxially. The two fourth layers 206 are respectively fitted inside and outside the third layer 205. During acid mixing, the second layer 104 inside the first layer 103 provides stable corrosion protection to prevent sulfuric acid from corroding the pipeline material. The fourth layers 206 provide reliable protection for the third layer 205, enhancing the durability and safety of the mixing component 200. When sulfuric acid is added to the first channel 101 through the second channel 202, a more stable barrier effect is obtained, achieving effective mixing of sulfuric acid and quench tower circulating liquid. At the same time, it provides good corrosion protection, reduces the risk of leakage, and achieves a more convenient and stable acid mixing purpose.

[0036] like Figure 1 , Figure 2 As shown, in an optional embodiment, the first layer 103 and the third layer 205 are made of stainless steel, and the second layer 104 and the fourth layer 206 are made of polytetrafluoroethylene.

[0037] The first layer 103 and the third layer 205 are both made of stainless steel. Stainless steel is chosen for its excellent corrosion resistance and strength, especially in chemical processing and high-temperature environments, where it provides good durability and stability. Using stainless steel in the first layer 103 of the circulation pipe 100 and the third layer 205 of the mixing component 200 effectively resists the corrosion of sulfuric acid and other chemicals, protecting the internal structure.

[0038] The second layer 104 and the fourth layer 206 are both made of polytetrafluoroethylene (PTFE). PTFE is chemically stable and non-sticky, and resistant to chemicals, including strong acids and alkalis. Using PTFE in the second layer 104 of the circulation line 100 and the fourth layer 206 of the mixing component 200 provides additional corrosion protection while reducing the adhesion of sulfuric acid and other chemicals.

[0039] like Figure 1 , Figure 2 As shown, in an optional embodiment, the second layer 104 is disposed inside the first layer 103 by a tight-fitting process, and the fourth layer 206 is disposed inside and outside the third layer 205 by a tight-fitting process.

[0040] The second layer 104 is formed inside the first layer 103 using a tight-fitting process. This process involves tightly bonding the lining material to the inside of the substrate, ensuring no gaps and providing a seamless protective layer. The tight-fitting process allows the polytetrafluoroethylene (PTFE) of the second layer 104 to adhere tightly to the inside of the stainless steel first layer 103, forming a continuous anti-corrosion layer that effectively prevents sulfuric acid and other chemicals from penetrating the substrate.

[0041] The fourth layer 206 is formed on both the inner and outer sides of the third layer 205 using a tight-fitting process. This means that the third layer 205 of the composite 200 is completely surrounded by the fourth layer 206 of polytetrafluoroethylene, both inside and outside. This not only enhances the corrosion resistance of the composite 200 but also improves structural integrity, ensuring long-term stability in high-pressure and corrosive environments.

[0042] By using a combination of stainless steel and PTFE, along with a tight-lining process, the corrosion resistance of the circulation line 100 and mixing component 200 is significantly enhanced, extending the service life of the equipment. This reduces the risk of sulfuric acid leakage and improves the safety of operators and the environment.

[0043] The non-sticky properties of polytetrafluoroethylene (PTFE) help reduce the adhesion of sulfuric acid and other chemicals, thereby optimizing mixing and flowability.

[0044] Due to the durability and corrosion resistance of the materials, the frequency of equipment maintenance and replacement is reduced, thereby lowering long-term operating costs.

[0045] In an optional embodiment, the thickness of the fourth layer 206 located inside the third layer 205 is not less than 12 mm, and the thickness of the other fourth layer 206 and the second layer 104 is not less than 3 mm.

[0046] like Figure 1 , Figure 2 As shown, in an optional embodiment, the circulation pipeline 100 is provided with a riser 301, the riser 301 is fixedly installed at the mounting hole 102, and the mixing component 200 is detachably connected to the riser 301.

[0047] A riser 301 is provided on the circulation pipeline 100. The riser 301 is fixed at the mounting hole 102, providing a stable connection point for the mixing component 200. The riser 301 allows the mixing component 200 to be easily disassembled and installed, which helps in the maintenance and replacement of the mixing component 200, and improves the flexibility of operation and the convenience of maintenance.

[0048] like Figure 1 , Figure 2 As shown, in an optional embodiment, the riser 301 is provided with a first annular platform 302, the mixing component 200 is provided with a second annular platform 201, the mixed acid system includes a clamping part 400 detachably connected to the first annular platform 302, and the second annular platform 201 extends between the clamping part 400 and the first annular platform 302.

[0049] The riser 301 has a first annular platform 302, while the mixing component 200 has a second annular platform 201. These two annular platforms enable a detachable connection between the mixing component 200 and the riser 301. The second annular platform 201 extends between the clamping part 400 and the first annular platform 302, which helps to form a seal during the connection process to prevent leakage of sulfuric acid and other chemicals.

[0050] The mixed acid system includes a clamping part 400 that is detachably connected to the first annular platform 302, the clamping part 400 ensuring a tight connection between the mixing component 200 and the riser 301.

[0051] The riser 301 and the detachable connection make the installation and removal of the hybrid component 200 more convenient, reducing maintenance time and labor intensity.

[0052] like Figure 1 , Figure 2As shown, in an optional embodiment, the pressing part 400 includes a third annular platform 401 pressed on the first annular platform 302, and a connecting section 402 coaxially arranged with the mixing component 200. The connecting section 402 includes a fifth layer 404 and a sixth layer 405 coaxially arranged, and the sixth layer 405 is fitted inside the fifth layer 404.

[0053] The clamping part 400 includes a third annular platform 401 pressed onto the first annular platform 302, and a connecting section 402 arranged coaxially with the mixing component 200. This helps to form a seal during connection while maintaining the stability of the system.

[0054] The connecting section 402 includes a fifth layer 404 and a sixth layer 405 arranged coaxially, wherein the sixth layer 405 is fitted inside the fifth layer 404. This not only enhances the strength of the connecting section 402 but also provides an additional sealing layer, ensuring the sealing performance between the mixing component 200 and the riser 301.

[0055] like Figure 1 , Figure 2 As shown, in an optional embodiment, the end of the connecting segment 402 away from the mixing component 200 is detachably connected to a connecting flange 403. This detachable connection of the connecting segment 402 to the connecting flange 403 allows for quick and safe connection of the connecting segment 402 to external equipment or piping.

[0056] The use of the 403 connecting flange provides a relatively standardized interface that facilitates installation and maintenance, while also allowing for quick disconnection when needed for system inspection or component replacement.

[0057] The presence of the 403 connecting flange also helps ensure the sealing of the connection and prevents leakage in high-pressure or corrosive environments.

[0058] like Figure 1 , Figure 2 As shown, in an optional embodiment, the second opening 204 is arranged on one side of the fourth layer 206 located inside the third layer 205, and the second opening 204 is opened in the direction of flow of the circulating liquid.

[0059] The second opening 204 is located on one side of the fourth layer 206, inside the third layer 205, so that sulfuric acid can be directly added to the circulating liquid without the need for additional pipes or channels.

[0060] The second opening 204 is oriented towards the flow direction of the circulating liquid, which helps to ensure thorough mixing of sulfuric acid and the circulating liquid, improves neutralization efficiency, and reduces problems that may be caused by uneven mixing. It also helps to reduce the direct impact of sulfuric acid on the pipe wall, thereby reducing corrosion and wear.

[0061] like Figure 1 , Figure 2 As shown, in an optional embodiment, the opening degree of the second opening 204 is 10°-90°. This range of opening degrees provides flexibility, allowing adjustment based on actual flow rate and mixing requirements. A smaller opening degree (e.g., 10°) of the second opening 204 can be used when precise control of the sulfuric acid flow rate is required, while a larger opening degree (e.g., 90°) can be used when a larger flow rate is needed to meet different operating conditions.

[0062] By pre-setting the opening of the second opening 204, the mixing efficiency of sulfuric acid and circulating liquid can be optimized, ensuring the efficiency and safety of the neutralization reaction, and also controlling the range and direction of sulfuric acid spraying.

[0063] It should be understood that the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit, without departing from the scope of the exemplary embodiments of the invention.

[0064] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it are in an "or" relationship.

[0065] It should be understood that in the description of this invention, the terms "upper," "vertical," "inner," "outer," etc., indicate the orientation or positional relationship as commonly placed when the disclosed product is used, or the orientation or positional relationship commonly understood by those skilled in the art. 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.

[0066] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0067] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” “containing,” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, and do not exclude the presence or addition of one or more other features, quantities, steps, operations, units, components, and / or combinations thereof.

[0068] Specific details are provided in the following description to provide a complete understanding of the exemplary embodiments. However, those skilled in the art will understand that the exemplary embodiments can be implemented without these specific details. In other embodiments, well-known processes, structures, and techniques may be omitted in the depiction of non-essential details to avoid obscuring the exemplary embodiments.

[0069] The above are merely specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

[0070] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art.

Claims

1. A mixed acid system for an acrylonitrile plant, characterized in that, The mixed acid system includes: A circulation pipeline is used to connect to the circulation pipeline of the quench tower. The circulation pipeline has a first channel for the flow of circulating liquid and an installation hole. The circulation pipeline includes a first layer and a second layer arranged coaxially, with the first layer fitted over the second layer. The mixing component has a second channel inside it, and a first opening and a second opening are respectively arranged at both ends of the second channel. The mixing component extends into the mounting hole and is fixedly connected to the circulation pipeline. The first opening is located outside the first channel, and the second opening is located inside the first channel. The mixing component includes a third layer and two fourth layers arranged coaxially. The two fourth layers are respectively fitted inside and outside the third layer.

2. The mixed acid system for an acrylonitrile plant as described in claim 1, characterized in that: The first and third layers are made of stainless steel, while the second and fourth layers are made of polytetrafluoroethylene.

3. The mixed acid system for an acrylonitrile plant as described in claim 2, characterized in that: The second layer is formed inside the first layer by a tight-fitting process, and the fourth layer is formed inside and outside the third layer by a tight-fitting process.

4. The mixed acid system for an acrylonitrile plant as described in claim 1, characterized in that: The thickness of the fourth layer located inside the third layer is not less than 12mm, and the thickness of the other fourth layer and the second layer is not less than 3mm.

5. The mixed acid system for an acrylonitrile plant as described in claim 1, characterized in that: The circulation pipeline is provided with a riser, which is fixedly installed at the mounting hole, and the mixing component is detachably connected to the riser.

6. The mixed acid system for an acrylonitrile plant as described in claim 5, characterized in that: The riser is provided with a first annular platform, the mixing component is provided with a second annular platform, the mixed acid system includes a clamping part detachably connected to the first annular platform, and the second annular platform extends between the clamping part and the first annular platform.

7. The mixed acid system for an acrylonitrile plant as described in claim 6, characterized in that: The pressing part includes a third annular platform pressed on the first annular platform, and a connecting section coaxially arranged with the mixture. The connecting section includes a fifth layer and a sixth layer coaxially arranged, with the sixth layer fitted inside the fifth layer.

8. The mixed acid system for an acrylonitrile plant as described in claim 7, characterized in that: The end of the connecting section away from the hybrid component is detachably connected to a connecting flange.

9. The mixed acid system for an acrylonitrile plant as described in claim 1, characterized in that: The second opening is located on one side of the fourth layer, inside the third layer, and the second opening faces the flow direction of the circulating liquid.

10. The mixed acid system for an acrylonitrile plant as described in claim 1, characterized in that: The opening of the second opening is 10°-90°.

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