Polymerization inhibition anti-coking ammonification reactor

Abstract

A gas raw material is tangentially fed at a mixing section, a first separation section is formed by nesting a plurality of annular surfaces which are coaxially arranged up and down, a catalyst outlet is formed in the bottom between the bottom end of each annular surface and the adjacent annular surface, a baffle is arranged at the bottom of a second separation section, and the baffle is arranged at the bottom of the second separation section. The outer edge of the baffle is connected with the side wall of the second separation section, a rising hole is formed in the center of the baffle, the top end of the annular face is connected with the edge of the rising hole, a product outlet is formed in the baffle around the rising hole, and a guide plate tangentially connected with the product outlet is vertically arranged between the baffle and the rising hole. And the inclination direction of a gap between the flow guide strips is consistent with the feeding direction of the gas raw material. The method provided by the invention has the characteristics of efficient side reaction inhibition, difficult catalyst deactivation, efficient energy utilization and catalyst regeneration energy saving, can significantly improve the reaction selectivity and the production efficiency, and can significantly save energy and reduce emission in both the reaction stage and the catalyst regeneration stage.

Description

Technical Field

[0001] This invention belongs to the field of reactor technology, specifically a polymerization-inhibiting and coking-resistant ammoniation reactor that can realize catalyst stage recovery and by-product separation, which can significantly reduce energy consumption and is suitable for ammoniation reactions using caprolactam solution generated by the rearrangement of cyclohexanone oxime in the fuming sulfuric acid liquid phase as raw material. Background Technology

[0002] 6-Aminohexanonitrile is an important intermediate in the production of nylon 66. Its industrial preparation often uses the liquid-phase rearrangement product of cyclohexanone oxime (caprolactam) as the main raw material, generated through an ammoniation reaction. However, existing ammoniation reaction equipment still faces the following key problems in actual production: Catalysts are prone to coking and deactivation, making recycling difficult: In high-temperature ammoniation reaction environments, the catalyst surface is easily coked due to the polymerization reaction of byproducts, leading to a rapid decline in catalyst activity and making it difficult to maintain efficient reaction. Furthermore, the regeneration process of coked catalysts is complex and costly, directly impacting the economics of production.

[0003] Polymer byproducts are difficult to separate efficiently: Polymer byproducts are easily generated during the amination reaction. These byproducts not only affect the purity of the target product, but may also clog equipment, leading to decreased equipment operating efficiency or frequent shutdowns for cleaning, increasing the complexity and cost of production.

[0004] Low efficiency in utilizing reaction heat: Ammoniation is a strongly exothermic reaction, but existing equipment makes low utilization of the exothermic reaction heat, usually dissipating the heat directly through cooling, resulting in energy waste. At the same time, uneven temperature distribution within the tower can easily trigger side reactions or reduce the selectivity of the target product.

[0005] To address the above issues, developing a novel reactor that optimizes gas-liquid mixing, catalyst staged recovery, byproduct separation, and thermal energy utilization to achieve efficient control of the entire ammoniation reaction process has become an important technological requirement for improving the preparation efficiency of 6-aminohexanonitrile. Summary of the Invention

[0006] To address the problems of catalyst deactivation due to coking, low recycling efficiency, high regeneration cost, and difficulty in precisely controlling the reaction temperature in existing technologies, this invention proposes an anti-polymerization and anti-coking ammoniation reactor. This reactor comprehensively optimizes the ammoniation reaction process, improves thermal energy utilization, reduces energy consumption for by-product separation, and reduces energy consumption for catalyst regeneration through innovative designs of a catalyst staged recovery system, a heat energy recovery and recycling system, and a high-efficiency by-product separation device.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An anti-polymerization and anti-coking ammoniation reactor is disclosed, wherein the reaction chamber of the reactor comprises, from bottom to top, a mixing section, a first separation section, and a second separation section, and the cross-section of the reaction chamber is circular. The liquid feed inlet is located at the top of the mixing section, and the gas feed inlet is located on the side wall of the mixing section, with the gas feed direction tangent to the mixing section. A material outlet is located at the top of the reaction chamber. The sidewall of the first separation section is composed of several coaxially arranged annular surfaces nested vertically. The top diameter of each annular surface is smaller than its bottom diameter, and the top of each annular surface is higher than the bottom of the adjacent annular surface above it. A catalyst outlet is provided at the bottom of the gap between the bottom of each annular surface and the adjacent annular surface below it. The lowest annular surface extends downward to form the sidewall of the mixing section. A baffle is horizontally installed at the bottom of the second separation section. The outer edge of the baffle engages with the side wall of the second separation section. A rising hole is formed in the center of the baffle, and the top of the highest annular surface connects to the edge of the rising hole. The baffle plate has several product outlets around the rising hole. A guide plate with its bottom connected to the baffle plate is erected between the product outlets and the rising hole, and the guide plate is tangentially connected to the product outlets. The inner wall of the second separation section is fitted with several parallel guide strips, with inclined gaps between the guide strips. The inclination direction is consistent with the feeding direction of the gaseous raw material from bottom to top. That is, when the gas is fed counterclockwise in the mixing section, the gaps at the guide strips are inclined counterclockwise from bottom to top, thus conforming to the rotation direction of the gas-liquid mixture. The reverse is also true.

[0008] Furthermore, the lower edge of the guide strip is above the upper edge of the guide plate.

[0009] Furthermore, the product outlet is connected to the inner wall of the second separation section, and the product outlet is uniformly surrounding the rising hole in the circumferential direction.

[0010] Furthermore, a plurality of catalyst scrapers are vertically connected to the inner wall of the annular surface. Preferably, the catalyst scrapers are uniformly arranged circumferentially along the annular surface.

[0011] Furthermore, the annular surface is wrapped with a first heat exchange section, which is filled with a heat-insulating medium, and a heat exchange pipe is disposed within the heat-insulating medium.

[0012] Furthermore, the mixing section is externally wrapped with a second heat exchange section, which is filled with a heat-insulating medium, and a heat exchange pipe is installed within the heat-insulating medium.

[0013] Furthermore, the liquid raw material inlet is connected to a liquid distribution device, which is located above the center of the mixing section.

[0014] Furthermore, the inner wall of the mixing section is also provided with guide strips, and the guide strips are arranged in the same way as the second separation section.

[0015] Furthermore, the gas raw material inlet is connected to a gas injection pipe, through which the gas raw material is injected into the mixing section.

[0016] Furthermore, the gas feedstock inlet has multiple locations, and the gas feedstock inlet directions are all either counterclockwise or all clockwise.

[0017] Furthermore, a residue outlet is provided at the bottom of the reaction chamber.

[0018] Furthermore, the material outlet is connected to the unreacted liquid outlet via a heat exchanger, and the fresh gas inlet is connected to the gas feedstock inlet via the same heat exchanger.

[0019] Furthermore, the heat exchange medium outlet of the heat exchanger is connected to the heat exchange pipe.

[0020] Furthermore, the guide plate is arc-shaped.

[0021] Furthermore, the polymerization-inhibiting and coking-resistant ammoniation reactor is used for the ammoniation reaction of cyclohexanone oxime liquid-phase rearrangement products.

[0022] The anti-polymerization and anti-caking coking ammoniation reactor of this invention features a mixing section where the feed gas is tangentially fed and mixed with the liquid feedstock, causing the reactants to rise in a spiral flow. In the first separation section, the catalyst in good condition in the reactants is centrifuged in the lower half and recovered from the gaps between the annular surfaces of adjacent stages, significantly reducing the catalyst regeneration requirement. The upper half of the first separation section recovers the catalyst in poor condition, which is then processed by a separate, dedicated, low-energy regeneration system and reused. The nested design of multiple annular surfaces in the first separation section allows for the staged recovery of catalysts in different states, reducing catalyst regeneration energy consumption by more than half, significantly lowering production costs, and extending catalyst lifespan.

[0023] Secondly, this invention fully absorbs the exothermic reaction during the process through the heat exchange medium. The heat exchange medium first absorbs the heat from the 6-aminohexanonitrile and unreacted ammonia in the gas phase exiting the top of the tower, achieving the condensation of 6-aminohexanonitrile and preheating the fresh ammonia. Subsequently, the heat exchange medium flows through the heat exchange pipes into the first separation section and mixing section, further absorbing the exothermic reaction and achieving precise temperature control and uniform distribution within the tower. This design effectively avoids side reactions and catalyst deactivation caused by localized overheating, while reducing the demand for external energy and improving overall energy utilization efficiency.

[0024] In addition, the second separation section adopts an optimized design to effectively separate the polymers and heavy components generated during the reaction process, preventing them from adhering to the inner wall of the equipment or clogging the reactor, thus ensuring the stability and continuity of the reaction process.

[0025] Preferably, the heat exchange medium is one or more of ammonia, water, mineral oil, silicone oil, and synthetic oil.

[0026] The beneficial effects of the invention are: This invention addresses the problems of easy catalyst coking and deactivation, low recycling efficiency, high regeneration cost, and difficulty in accurately controlling the reaction temperature in existing technologies. It proposes an anti-polymerization and anti-coking ammoniation reactor that can be used for the ammoniation of cyclohexanone oxime liquid-phase rearrangement products. Through the innovative design of a catalyst staged recovery system, a heat energy recovery and recycling system, and a high-efficiency by-product separation device, the ammoniation reaction process is comprehensively optimized, and the overall production energy consumption is reduced. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the anti-polymerization and anti-coking ammonialation reactor described in this invention.

[0028] Figure 2 This is a top view of the baffle structure.

[0029] Figure 3 This is a three-dimensional structural diagram of the baffle and guide vane.

[0030] Wherein, 1 is the mixing section, 2 is the first separation section, 3 is the second separation section, 4 is the liquid distribution device, 5 is the catalyst outlet, 6 is the gas feed inlet, 7 is the riser hole, 8 is the guide strip, 9 is the catalyst scraper, 10 is the heat exchange pipe, 11 is the product outlet, 12 is the guide plate, 13 is the baffle, 14 is the fresh gas inlet, 15 is the heat exchange medium inlet, 16 is the unreacted liquid outlet, 17 is the heat exchange medium outlet, 18 is the heat exchanger, 19 is the reactor residue outlet, 20 is the insulation medium, and 21 is the gas injection pipe. Detailed Implementation

[0031] like Figures 1-3The diagram illustrates an anti-polymerization and anti-coking ammonialation reactor. The reactor's reaction chamber, from bottom to top, comprises a mixing section 1, a first separation section 2, and a second separation section 3. The reaction chamber has a circular cross-section. A liquid feed inlet 6 is located at the top of the mixing section, and a gas feed inlet 6 is located on the side wall of the mixing section, with the gas feed direction tangential to the mixing section. A material outlet is located at the top of the reaction chamber. The side wall of the first separation section 2 is composed of several coaxially arranged nested annular surfaces. The top diameter of each annular surface is smaller than its bottom diameter, and the top of each annular surface is higher than the bottom of its adjacent annular surface. A catalyst outlet 5 is located at the bottom of the gap between the bottom of each annular surface and its adjacent annular surface below it. The lower annular surface extends downward to form the sidewall of the mixing section 1. A baffle 13 is horizontally arranged at the bottom of the second separation section 3. The outer edge of the baffle 13 is joined to the sidewall of the second separation section 3. A rising hole 7 is opened in the center of the baffle 13. The top of the highest annular surface is connected to the edge of the rising hole 7. Several product outlets 11 are opened on the baffle 13 around the rising hole 7. A guide plate 12 with its bottom connected to the baffle 13 is erected between the product outlets 11 and the rising hole 7. The guide plate 12 is tangentially connected to the product outlets 11. Several parallel guide strips 8 are attached to the inner wall of the second separation section 3. An inclined gap is left between the guide strips 8. The inclined direction is consistent with the feeding direction of the gas raw material from bottom to top.

[0032] The lower edge of the guide strip 8 is above the upper edge of the guide plate 12.

[0033] The product outlet 11 is connected to the inner wall of the second separation section 3, and the product outlet 11 is uniformly surrounding the rising hole 7 in the circumferential direction.

[0034] A plurality of catalyst scrapers 9 are vertically connected to the inner wall of the annular surface. Preferably, the catalyst scrapers 9 are uniformly arranged along the circumference of the annular surface.

[0035] The annular surface is surrounded by a first heat exchange section, which is filled with a heat-insulating medium 20, and a heat exchange pipe 10 is disposed within the heat-insulating medium 20.

[0036] The mixing section 1 is externally wrapped with a second heat exchange section, which is filled with a heat-insulating medium, and a heat exchange pipe is installed in the heat-insulating medium.

[0037] The liquid raw material inlet is connected to the liquid distribution device 4, which is located above the center of the mixing section 1.

[0038] The inner wall of the mixing section 1 is also provided with guide strips 8, and the guide strips 8 are arranged in the same way as the second separation section.

[0039] The gas raw material inlet 6 is connected to the gas injection pipe 21, and gas is injected into the mixing section 1 through the gas injection pipe 21.

[0040] There are multiple gas feed inlets 6, and the gas feed directions are all either counterclockwise or all clockwise.

[0041] The bottom of the reaction chamber is provided with a residue outlet 19.

[0042] The material outlet is connected to the unreacted liquid outlet 16 via heat exchanger 18, and the fresh gas inlet 14 is connected to the gas raw material inlet 6 via heat exchanger 18.

[0043] The heat exchange medium outlet 17 of the heat exchanger 18 is connected to the heat exchange pipe 10.

[0044] The guide plate 12 is arc-shaped.

[0045] Example 1 This apparatus was used to perform the ammoniation reaction of cyclohexanone oxime liquid-phase rearrangement products.

[0046] The caprolactam solution obtained from the cyclohexanone oxime rearrangement process was used as the feed solution, and a comparative experiment was conducted between a conventional fluidized bed reactor and the ammoniation reactor of this invention. The operating conditions are shown in Table 1, and the reaction results are compared in Table 2.

[0047] Table 1 Operating conditions for Example 1 .

[0048] Table 2 Comparison of reaction results .

[0049] Example 2 This apparatus was used to perform the ammoniation reaction of cyclohexanone oxime liquid-phase rearrangement products.

[0050] The caprolactam solution obtained from the cyclohexanone oxime rearrangement process was used as the feed solution, and a comparative experiment was conducted between a conventional fluidized bed reactor and the ammoniation reactor of this invention. The operating conditions are shown in Table 3, and the reaction results are compared in Table 4.

[0051] Table 3 Operating conditions for Example 2 .

[0052] Table 4 Comparison of reaction results .

[0053] Example 3 This apparatus was used to perform the ammoniation reaction of cyclohexanone oxime liquid-phase rearrangement products.

[0054] The caprolactam solution obtained from the cyclohexanone oxime rearrangement process was used as the feed solution, and a comparative experiment was conducted between a conventional fluidized bed reactor and the ammoniation reactor of this invention. The operating conditions are shown in Table 5, and the reaction results are compared in Table 6.

[0055] Table 5 Operating conditions for Example 3 .

[0056] Table 6 Comparison of reaction results .

[0057] Example 4 This apparatus was used to perform the ammoniation reaction of cyclohexanone oxime liquid-phase rearrangement products.

[0058] The caprolactam solution obtained from the cyclohexanone oxime rearrangement process was used as the feed solution, and a comparative experiment was conducted between a conventional fluidized bed reactor and the ammoniation reactor of this invention. The operating conditions are shown in Table 7, and the reaction results are compared in Table 8.

[0059] Table 7 Operating conditions for Example 4 .

[0060] Table 8 Comparison of reaction results .

Claims

1. A polymerization-inhibiting and coking-resistant ammoniation reactor, characterized in that, The reaction chamber of the anti-polymerization and anti-coking ammoniaation reactor consists of a mixing section (1), a first separation section (2), and a second separation section (3) from bottom to top. The cross-section of the reaction chamber is circular. The liquid raw material inlet is located at the top of the mixing section, and the gas raw material inlet (6) is located on the side wall of the mixing section. The gas raw material feeding direction is tangent to the mixing section. The material outlet is located at the top of the reaction chamber. The sidewall of the first separation section (2) is composed of several coaxially arranged annular surfaces nested one above the other. The top diameter of each annular surface is smaller than the bottom diameter. The top of each annular surface is higher than the bottom of the adjacent annular surface above it. A catalyst outlet (5) is provided at the bottom of the gap between the bottom of each annular surface and the adjacent annular surface below it. The lowest annular surface extends downward to form the sidewall of the mixing segment (1). A baffle (13) is horizontally arranged at the bottom of the second separation section (3). The outer edge of the baffle (13) is joined to the side wall of the second separation section (3). A rising hole (7) is opened in the center of the baffle (13). The top of the highest annular surface is connected to the edge of the rising hole (7). The baffle (13) has a plurality of product outlets (11) around the rising hole (7). A guide plate (12) with its bottom connected to the baffle (13) is erected between the product outlets (11) and the rising hole (7). The guide plate (12) is tangentially connected to the product outlets (11). The inner wall of the second separation section (3) is fitted with several parallel guide strips (8), and there are inclined gaps between the guide strips (8), with the inclination direction from bottom to top consistent with the feeding direction of the gas raw material.

2. The anti-polymerization and anti-coking ammonialation reactor according to claim 1, characterized in that, The product outlet (11) is connected to the inner wall of the second separation section (3).

3. The anti-polymerization and anti-coking ammoniation reactor according to claim 1, characterized in that, Several catalyst scrapers (9) are vertically connected to the inner wall of the annular surface.

4. The anti-polymerization and anti-coking ammonialation reactor according to claim 1, characterized in that, The annular surface is wrapped with a first heat exchange section, which is filled with a heat-insulating medium (20). A heat exchange pipe (10) is installed in the heat-insulating medium (20).

5. The anti-polymerization and anti-coking ammonialation reactor according to claim 1, characterized in that, The inner wall of the mixing section (1) is also provided with guide strips (8), and the guide strips (8) are arranged in the same way as the second separation section.

6. The anti-polymerization and anti-coking ammonialation reactor according to claim 1, characterized in that, The gas raw material inlet (6) is connected to the gas injection pipe (21), and the gas raw material is injected into the mixing section (1) through the gas injection pipe (21).

7. The anti-polymerization and anti-coking ammonialation reactor according to claim 1, characterized in that, There are multiple gas raw material inlets (6), and the gas raw material feeding direction is set to be either counterclockwise or clockwise.

8. The anti-polymerization and anti-coking ammonialation reactor according to claim 1, characterized in that, The material outlet is connected to the unreacted liquid outlet (16) via a heat exchanger (18), and the fresh gas inlet (14) is connected to the gas raw material inlet (6) via the heat exchanger (18).

9. The anti-polymerization and anti-coking ammonialation reactor according to claim 1, characterized in that, The guide plate (12) is arc-shaped.

10. The anti-polymerization and anti-coking ammonialation reactor according to any one of claims 1-9, characterized in that, The polymerization-inhibiting and coking-resistant ammoniation reactor is used for the ammoniation reaction of cyclohexanone oxime liquid-phase rearrangement products.

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