A cyclohexanone oxime rearrangement mixer structure, numerical simulation calculation model and analysis method

Abstract

This invention relates to the field of chemical production technology and discloses a cyclohexanone oxime rearrangement mixer structure, a numerical simulation model, and an analysis method. The cyclohexanone oxime rearrangement mixer structure includes a main structure, a circular ring, a cyclohexanone oxime inlet, and cyclohexanone oxime orifices. The main structure is vertical, with a circulating liquid inlet, a throat, and a mixture outlet arranged sequentially from top to bottom. A circulating liquid containing caprolactam, sulfuric acid, and SO3 flows into the main structure from the circulating liquid inlet. The circular ring is fitted onto the main structure and located between the circulating liquid inlet and the throat. To achieve thorough mixing of cyclohexanone oxime and the circulating liquid, the numerical simulation model is constructed using the Eulerian multiphase flow model and the Realizable k-ε turbulence model. The momentum ratio (MR) is used as an evaluation index for mixing effect, ensuring the momentum ratio is within a suitable range of 1-4, thereby achieving efficient mixing.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, specifically to a cyclohexanone oxime rearrangement mixer structure, numerical simulation calculation model, and analysis method. Background Technology

[0002] Cyclohexanone oxime rearrangement mixers are key equipment in the caprolactam production process. Their core function is to precisely inject cyclohexanone oxime into a circulating liquid containing caprolactam, sulfuric acid, and SO3, thereby providing favorable reaction conditions for subsequent rearrangement reactions. In the chemical production field, the mixing efficiency and equipment stability of mixers directly affect product yield, quality, and production costs. Numerical simulation technology based on computational fluid dynamics (CFD) has become a core means for optimizing mixer structure and improving performance, and is widely used in the design and improvement of fluid machinery.

[0003] However, existing cyclohexanone oxime rearrangement mixers have certain shortcomings in actual operation: On the one hand, the design of the cyclohexanone oxime orifice position in the original structure is unreasonable, and the jet flow rate is much smaller than the main flow rate, making it difficult for cyclohexanone oxime to effectively penetrate the main flow channel, resulting in poor mixing uniformity and affecting reaction efficiency; on the other hand, the vertical impact of the high-speed main flow and the jet near the orifice will cause a sudden change in the velocity gradient, causing local fluid stagnation and forming periodic vortices, which will significantly increase the local shear force, accelerate equipment corrosion, and shorten the service life of the equipment; at the same time, the existing technology lacks accurate numerical simulation models and systematic analysis methods, making it impossible to efficiently determine the optimal structural parameters and operating conditions, and making it difficult to balance the mixing effect and the equipment corrosion protection requirements.

[0004] In view of this, we propose a cyclohexanone oxime rearrangement mixer structure, a numerical simulation calculation model, and an analysis method. Summary of the Invention

[0005] The purpose of this invention is to provide a cyclohexanone oxime rearrangement mixer structure, a numerical simulation model, and an analysis method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A cyclohexanone oxime rearrangement mixer structure includes a main structure, a ring sleeve, a cyclohexanone oxime inlet, and cyclohexanone oxime orifices. The main structure is a vertical structure with a circulating liquid inlet, a throat, and a mixture outlet arranged sequentially from top to bottom. A circulating liquid containing caprolactam, sulfuric acid, and SO3 flows into the main structure from the circulating liquid inlet. The ring sleeve is fitted onto the main structure and located between the circulating liquid inlet and the throat. The cyclohexanone oxime inlet is connected to the ring sleeve. The cyclohexanone oxime orifices are uniformly arranged in a ring on the ring sleeve. After entering the ring sleeve through the cyclohexanone oxime inlet, the cyclohexanone oxime is sprayed into the circulating liquid through the cyclohexanone oxime orifices and undergoes a rearrangement reaction.

[0007] In a further embodiment, the cyclohexanone oxime orifice is located within a negative pressure zone of 0-15 mm above the throat section, preferably 3 mm or 15 mm above the throat section.

[0008] In a further embodiment, the diameter of the cyclohexanone oxime pore can be adjusted to 1-2 mm, and the angle of the expansion section of the main structure is 40°-60°.

[0009] A numerical simulation model for the cyclohexanone oxime rearrangement mixer includes a physical model and a mathematical model. The physical model is a three-dimensional fluid domain model based on the mixer's geometry, covering the entire fluid flow area from the circulating liquid inlet to the mixture outlet. It uses an unstructured mesh, which includes triangular, quadrilateral, tetrahedral, hexahedral, pyramidal, or hybrid unstructured meshes. The mathematical model includes an Eulerian multiphase flow model and a Realizable k-ε turbulence model, used to simulate the momentum exchange, mixing process, and turbulent flow characteristics between cyclohexanone oxime and the circulating liquid within the mixer.

[0010] In a further embodiment, the governing equations of the mathematical model include the mass conservation equation, the momentum conservation equation, and the transport equations of the Realizable k-ε turbulence model.

[0011] In a further embodiment, the boundary conditions of the calculation model are set as follows: both the circulating liquid inlet and the cyclohexanone oxime inlet are velocity inlets, the mixture outlet is a pressure outlet, and the inner wall of the main structure adopts an adiabatic non-slip boundary.

[0012] An analysis method, based on the numerical simulation calculation model, includes the following steps: S1: Import the physical property parameters of the circulating liquid and cyclohexanone oxime into the numerical simulation calculation model; S2: Using the controlled variable method, adjust the expansion section angle, cyclohexanone oxime orifice position, cyclohexanone oxime inlet flow rate, and cyclohexanone oxime orifice diameter; S3: The pressure distribution, cyclohexanone oxime velocity distribution, and fluid motion trajectory within the mixer are obtained by solving the numerical simulation model; S4: Introduce momentum ratio (MR) as an evaluation index for mixing effect; S5: Based on the momentum ratio and flow field distribution results, analyze the mixing effect and equipment corrosion risk, and determine the optimal structural and operating parameters.

[0013] In a further embodiment, the adjustment range of the expansion section angle in S2 is 40°-60°, the adjustment range of the cyclohexanone oxime orifice position is 0-15mm upward from the throat section, the adjustment range of the cyclohexanone oxime inlet flow rate is 12800-40000kg / h, and the adjustment range of the cyclohexanone oxime orifice diameter is 1-3mm.

[0014] In a further embodiment, when the mixer structure and operating parameters remain unchanged, the changes in jet parameters also affect the mixing effect. The flow velocity and jet area at the cyclohexanone oxime inlet and the cyclohexanone oxime orifice are determined based on the law of conservation of mass.

[0015] In a further embodiment, when MR < 1 in S4, it indicates that the momentum of the jet is insufficient and it is easily dispersed by the mainstream, resulting in low mixing efficiency; when MR > 4, it will cause the momentum of the jet to be too large, increasing the pressure loss. That is, the optimal structural parameters and operating parameters in S5 satisfy the momentum ratio MR being between 1 and 4.

[0016] Compared with the prior art, the present invention provides a cyclohexanone oxime rearrangement mixer structure, a numerical simulation calculation model, and an analysis method, which have the following beneficial effects: 1. In order to achieve thorough mixing of cyclohexanone oxime and circulating fluid, this invention constructs a numerical simulation model using the Eulerian multiphase flow model and the Realizable k-ε turbulence model. Combined with momentum ratio MR as the evaluation index of mixing effect, the negative pressure zone range of 0-15mm above the throat section of the cyclohexanone oxime orifice position is adjusted, the orifice diameter is reduced to 1-2mm, and the cyclohexanone oxime inlet flow rate is increased to 12800-40000kg / h, so that the momentum ratio is in a suitable range of 1-4, thereby achieving efficient mixing.

[0017] 2. In order to reduce the risk of corrosion in mixer equipment, this invention moves the position of the cyclohexanone oxime orifice upward, thereby reducing the impact and collision between the cyclohexanone oxime and the mainstream, reducing local fluid stagnation and eddy effects, reducing local shear force, and optimizing jet parameters to avoid the generation of periodic vortices, thus effectively controlling the occurrence of corrosion.

[0018] 3. In order to accurately obtain the flow field characteristics and mixing effect data in the mixer, this invention establishes a three-dimensional fluid domain physical model covering the entire fluid flow area from the circulating liquid inlet to the mixture outlet, adopts unstructured mesh generation, sets reasonable boundary conditions, and uses numerical simulation to solve for pressure distribution, velocity distribution and fluid motion trajectory, thereby providing reliable data support for structural optimization.

[0019] 4. In order to efficiently determine the optimal structural and operating parameters of the mixer, this invention adopts the controlled variable method to adjust the expansion section angle within the range of 40°-60°, and adjust parameters such as the position of the orifice, flow rate and diameter within a reasonable range. Combined with numerical simulation results and momentum ratio analysis, the parameter combination that takes into account both mixing effect and low corrosion risk is quickly screened out, thereby improving the efficiency of mixer structure optimization. Attached Figure Description

[0020] Figure 1 This is a three-dimensional schematic diagram of the cyclohexanone oxime rearrangement mixer of the present invention; Figure 2 This is a schematic diagram of the cyclohexanone oxime orifice of the present invention; Figure 3 This is a schematic diagram of the mesh model of the cyclohexanone oxime rearrangement mixer of the present invention; Figure 4 This is a velocity distribution diagram of cyclohexanone oxime at a 40° expansion angle according to the present invention; Figure 5 This is a velocity distribution diagram of cyclohexanone oxime at a 50° expansion angle according to the present invention; Figure 6 This is a velocity distribution diagram of cyclohexanone oxime at a 60° expansion angle according to the present invention; Figure 7 This is a pressure distribution diagram at the original location of the small hole in this invention; Figure 8 This is a pressure distribution diagram at the 3mm orifice location of the present invention; Figure 9 This is a pressure distribution diagram at the 15mm orifice location of the present invention; Figure 10 This is a flow velocity distribution diagram of cyclohexanone oxime at the original orifice location of the present invention; Figure 11 This is a flow rate distribution diagram of cyclohexanone oxime at the 3mm orifice location in this invention; Figure 12 This is a flow rate distribution diagram of cyclohexanone oxime at the 15mm orifice location of the present invention; Figure 13 This is a comparison diagram of the flow trajectory at the original position of the small hole in this invention; Figure 14 This is a comparison diagram of the flow trajectory at the 3mm orifice position of the present invention; Figure 15 This is a comparison diagram of the flow trajectory at the 15mm orifice position of the present invention; Figure 16 This is a flowchart of the method of the present invention.

[0021] Explanation of icon numbers: 1. Main structure; 11. Circulating fluid inlet; 12. Mixture outlet; 13. Throat; 2. Circular sleeve; 3. Cyclohexanone oxime inlet; 4. Cyclohexanone oxime orifice. Detailed Implementation

[0022] The technical solutions of the embodiments 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.

[0023] In this application, the term "above" indicates the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. It is primarily used to better describe this application and its embodiments, and is not intended to limit the indicated device, element, or component to having a specific orientation, or to construct and operate in a specific orientation. Furthermore, the term "above" may also be used in certain circumstances to indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application according to the specific circumstances.

[0024] Please see Figures 1-16 The present invention provides a technical solution: A cyclohexanone oxime rearrangement mixer structure includes a main structure 1, a circular ring 2, a cyclohexanone oxime inlet 3, and a cyclohexanone oxime orifice 4. The main structure 1 is a vertical structure, with a circulating liquid inlet 11, a throat 13, and a mixture outlet 12 arranged sequentially from top to bottom. A circulating liquid containing caprolactam, sulfuric acid, and SO3 flows into the main structure 1 through the circulating liquid inlet 11. The diameter of the cyclohexanone oxime orifice 4 is adjustable to 1-2 mm, and the expansion angle of the main structure 1 is 40°-60°. Additionally, the ring... The position of the cyclohexanone oxime orifice 4 is within the negative pressure zone of 0-15 mm above the throat 13 cross section, preferably 3 mm or 15 mm above the throat 13 cross section. The annular sleeve 2 is fitted on the main structure 1 and is located between the circulating liquid inlet 11 and the throat 13. The cyclohexanone oxime inlet 3 is connected to the annular sleeve 2. The cyclohexanone oxime orifice 4 is uniformly arranged in a ring on the annular sleeve 2. After the cyclohexanone oxime enters the annular sleeve 2 through the cyclohexanone oxime inlet 3, it is sprayed into the circulating liquid through the cyclohexanone oxime orifice 4 and undergoes a rearrangement reaction.

[0025] A numerical simulation model for a cyclohexanone oxime rearrangement mixer includes a physical model and a mathematical model. The physical model is a three-dimensional fluid domain model based on the mixer's geometry, covering the entire fluid flow area from the circulating liquid inlet 11 to the mixture outlet 12. It uses an unstructured mesh, which includes triangular, quadrilateral, tetrahedral, hexahedral, pyramidal, or hybrid unstructured meshes. The mathematical model includes an Eulerian multiphase flow model and a Realizable k-ε turbulence model, used to simulate the momentum exchange, mixing process, and turbulent flow characteristics between cyclohexanone oxime and the circulating liquid within the mixer.

[0026] Furthermore, the governing equations of the mathematical model include the mass conservation equation, the momentum conservation equation, and the transport equations of the Realizable k-ε turbulence model; The mass conservation equation is:

[0027] The momentum conservation equation is:

[0028] stress tensor Represented as:

[0029] Where t is time, in seconds; Density, unit: kg / m³; P is the velocity vector, unit: m / s; P is the pressure, unit: Pa. Dynamic viscosity, unit: (N·s) / m; Unit tensor; The transport equation for the Realizable k-ε turbulence model is:

[0030] in, The turbulent kinetic energy generated by the average velocity gradient; For turbulent dissipation; The turbulent kinetic energy dissipation rate; The constant is used. In addition, the boundary conditions of the calculation model are set as follows: the circulating liquid inlet 11 and the cyclohexanone oxime inlet 3 are both velocity inlets, the mixture outlet 12 is a pressure outlet, and the inner wall of the main structure 1 adopts an adiabatic non-slip boundary.

[0031] An analytical method, based on a numerical simulation computational model, includes the following steps: S1: Import the physical property parameters of the circulating liquid and cyclohexanone oxime into the numerical simulation calculation model; S2: Using the controlled variable method, adjust the angle of the expansion section, the position of the cyclohexanone oxime orifice 4, the flow rate of the cyclohexanone oxime inlet 3, and the diameter of the cyclohexanone oxime orifice 4; S3: The pressure distribution, cyclohexanone oxime velocity distribution, and fluid motion trajectory within the mixer are obtained by solving the numerical simulation model; S4: Introduce momentum ratio (MR) as an evaluation index for mixing effect:

[0032] in, The density of cyclohexanone oxime. The jet velocity of cyclohexanone oxime. The jet area for cyclohexanone oxime is... The density of the circulating fluid, As the mainstream speed, Mainstream flow area; S5: Based on the momentum ratio and flow field distribution results, analyze the mixing effect and equipment corrosion risk, and determine the optimal structural and operating parameters.

[0033] In addition, the adjustment range of the expansion section angle in S2 is 40°-60°, the adjustment range of the position of the cyclohexanone oxime orifice 4 is 0-15mm upward from the throat section 13, the adjustment range of the cyclohexanone oxime inlet 3 flow rate is 12800-40000kg / h, and the adjustment range of the diameter of the cyclohexanone oxime orifice 4 is 1-3mm.

[0034] Furthermore, when the mixer structure and operating parameters remain constant, changes in the jet parameters also affect the mixing effect. The flow velocity and jet area at the cyclohexanone oxime inlet 3 and the cyclohexanone oxime orifice 4 are determined based on the law of conservation of mass, as shown below:

[0035] Since the medium is cyclohexanone oxime, the mass conservation equation is expressed as: .

[0036] In addition, in S4, when MR<1, it indicates that the momentum of the jet is insufficient and it is easily dispersed by the mainstream, resulting in low mixing efficiency; when MR>4, it will cause the momentum of the jet to be too large, increasing the pressure loss. That is, in S5, the optimal structural parameters and operating parameters satisfy the momentum ratio MR being between 1 and 4.

[0037] Example 1: Basic Parameter Verification Example 1.1 Mixer structural parameter settings The structural parameters of the cyclohexanone oxime rearrangement mixer used in this embodiment strictly follow the basic design standards shown in Table 1-1 to ensure consistency with actual industrial application scenarios. Table 1-1 Mixer Basic Structure Parameters

[0038] The cyclohexanone oxime orifice 4 is located 3mm above the throat section 13 (within the negative pressure zone). The expansion section angle of the main structure 1 is set to 50°. The cyclohexanone oxime orifices 4 are arranged in a ring and there are 13 of them.

[0039] 1.2 Numerical Simulation Computation Model Construction Physical Model: A three-dimensional fluid domain model is established based on the mixer geometry, covering the complete flow area from the circulating liquid inlet 11 to the mixture outlet 12. Tetrahedral unstructured meshing is used, and the average mesh quality compliance rate is ≥92% to ensure the accuracy of flow field calculation. Mathematical model: The Eulerian multiphase flow model and the Realizable k-ε turbulence model are combined. The governing equations include the mass conservation equation, the momentum conservation equation, and the transport equations of the Realizable k-ε turbulence model. Table 2-1 Process Parameters

[0040] 1.3 Simulation Analysis Process Follow the analytical method steps proposed in this invention: S1. Import the medium property parameters in Table 2-1 into the materials module of FLUENT software to complete the fluid property definition; S2. Using the controlled variable method, the expansion section angle is fixed at 50°, the diameter of the cyclohexanone oxime orifice 4 is 3mm, and the inlet flow rate is 12800kg / h, with only the position of the cyclohexanone oxime orifice 4 remaining as a variable (in this embodiment, it is fixed at 3mm). S3. Start the numerical simulation solution and iterate until the residual converges (the residual is less than 1e-4). Output the pressure distribution, cyclohexanone oxime velocity distribution and fluid motion trajectory data in the mixer. S4. Introduce momentum ratio (MR) as an evaluation index, according to the formula:

[0041] Calculate the blending effect; S5. Combining flow field distribution and momentum ratio values, analyze the mixing uniformity and equipment corrosion risk.

[0042] 1.4 Implementation Results In this embodiment, the calculated momentum ratio MR = 0.88, the cyclohexanone oxime jet velocity is 118.5 m / s, and the mainstream velocity at the jet contact surface is 34.18 m / s. From the flow field results, the cyclohexanone oxime jet, due to insufficient momentum, cannot effectively penetrate the mainstream channel, and only forms shallow mixing at the mainstream contact surface, resulting in poor mixing uniformity. At the same time, a significant abrupt change in velocity gradient occurs near the cyclohexanone oxime orifice 4, and the fluid locally stagnates to form periodic vortices, with local shear force reaching 18.2 Pa, indicating a high risk of equipment corrosion. This result is consistent with the defects of the prior art, verifying the accuracy of the numerical simulation model of this invention.

[0043] Example 2: Optimization of the position of cyclohexanone oxime orifice 4 2.1 Variable Setting and Model Building This embodiment is based on Example 1, only adjusting the position of the cyclohexanone oxime orifice 4 and setting three variable levels: the original position (at the throat 13 section), 3mm above the throat 13 section, and 15mm above the throat 13 section. All other structural parameters, process parameters, and numerical simulation models are consistent with Example 1.

[0044] 2.2 Simulation Analysis Process Following the analysis steps of Example 1, numerical simulations were performed on the working conditions at the three cyclohexanone oxime orifices at position 4, focusing on monitoring the distribution of the negative pressure zone, the jet penetration depth, the area of ​​the vortex region, and the changes in local shear force.

[0045] 2.3 Implementation Results The key performance indicators for different cyclohexanone oxime well positions 4 are shown in Table 3-1: Table 3-1 Comparison of properties of different cyclohexanone oximes at 4-hole positions

[0046] The results show that as the position of the cyclohexanone oxime orifice 4 moves upward, the momentum ratio gradually increases, the jet penetration depth is significantly improved, and the vortex area and local shear force are greatly reduced. When the position of the cyclohexanone oxime orifice 4 is 15 mm above the throat section 13, the mixing uniformity reaches 94%, the local shear force drops to 6.2 Pa, and the corrosion risk is significantly reduced. This is because after the cyclohexanone oxime orifice 4 moves upward to the starting region of the negative pressure zone, the mainstream flow velocity decreases, the velocity gradient decreases, and the shearing effect on the jet weakens, enabling it to effectively penetrate the core region of the mainstream and achieve full mixing.

[0047] Example 3: Optimization of Jet Parameters 3.1 Variable Setting and Model Building In this embodiment, the position of the cyclohexanone oxime orifice 4 is fixed at 15mm upward from the throat section 13 and the expansion angle is 50°. The focus is on optimizing the jet parameters, and four sets of working conditions are set. The specific parameters are shown in Table 3-2. Table 3-2 Optimization of Jet Parameters under Operating Conditions

[0048] The numerical simulation model follows the settings of Example 1 to ensure the uniqueness of variable control.

[0049] 3.2 Simulation Analysis Process According to the analysis method of this invention, four sets of working conditions were simulated sequentially, based on the law of conservation of mass (… Calculate the jet velocity and analyze the mixing effect using the momentum ratio formula.

[0050] 3.3 Implementation Results The key performance indicators for the four operating conditions are shown in Table 3-3: Table 3-3 Effect of Jet Parameter Optimization

[0051] The results showed that reducing the diameter of the cyclohexanone oxime orifice 4 or increasing the flow rate of the cyclohexanone oxime inlet 3 could significantly improve the momentum ratio and mixing uniformity. Among them, the momentum ratio of condition 4 (orifice diameter 2 mm, flow rate 40000 kg / h) reached 3.096, which is within the optimal range of 1-4. The mixing uniformity was as high as 99.5%, and the pressure loss was controlled within a reasonable range of 0.45 MPa. Under this condition, the jet could completely penetrate the mainstream channel to form a uniform mixing flow field. The local fluid stagnation phenomenon was basically eliminated, and the equipment corrosion risk was reduced to a low level, achieving a balance between mixing effect and operational stability.

[0052] Example 4: Verification Example of the Influence of Expansion Segment Angle 4.1 Variable Setting and Model Building In this embodiment, the position of the cyclohexanone oxime orifice 4 is fixed at 15mm upward from the throat section 13, the diameter of the cyclohexanone oxime orifice 4 is 2mm, the flow rate of the cyclohexanone oxime inlet 3 is 40000kg / h, and the angle of the expansion section is adjusted to three levels of 40°, 50° and 60°. The remaining parameters are consistent with the working condition 4 of embodiment 3.

[0053] 4.2 Simulation Analysis Process Numerical simulations were used to obtain data on the velocity distribution of cyclohexanone oxime, the size of the reflux zone, and the mixing effect under different expansion section angles. The focus was on analyzing the impact of angle changes on mixing uniformity and corrosion risk.

[0054] 4.3 Implementation Results The performance test results for different expansion segment angles are shown in Table 3-4: Table 3-4 Results of the Influence of Expansion Section Angle

[0055] The results show that when the expansion section angle is within the range of 40°-60°, the mixing uniformity can reach over 97.5%. However, the angle change has a significant impact on the volume of the reflux zone and the local shear force. When the angle is 50°, the mixing uniformity is the highest (99.5%), the reflux zone volume is moderate, and the local shear force is low. When the angle increases to 60°, the reflux zone volume increases, the local shear force increases, and the corrosion risk increases slightly. When the angle decreases to 40°, the mixing uniformity decreases slightly, but the reflux zone is the smallest and the shear force is the lowest. In summary, the change of the expansion section angle cannot fundamentally affect the mixing effect. The optimal angle selection needs to be determined based on the actual process requirements for mixing uniformity and pressure loss, with 50° being the preferred choice.

[0056] Example 5: Optimal Parameter Combination Verification Example 5.1 Optimal Parameter Setting Based on the research results of the above embodiments, the optimal parameter combination is determined as follows: Cyclohexanone oxime orifice 4 location: 15mm upward from the throat section 13; Cyclohexanone oxime orifice diameter 4: 2mm; Cyclohexanone oxime inlet flow rate 3: 40000 kg / h; Expansion section angle: 50°.

[0057] 5.2 Simulation Verification and Industrial Application Results The mixer structure and numerical simulation model were built according to the optimal parameter combination, and the whole process simulation was verified. The parameter combination was then applied to an industrial test device. The simulation results showed that the momentum ratio MR=3.096, the mixing uniformity was 99.5%, the local shear force was 5.8Pa, and the pressure loss was 0.45MPa. All indicators met the design requirements. After 3 months of industrial test operation, the equipment corrosion rate dropped to 0.08mm / a, which was 77.1% lower than the original structure (corrosion rate 0.35mm / a). The purity of caprolactam product increased from 98.2% to 99.8%, and the production efficiency increased by 15%, verifying the practicality and superiority of the present invention.

[0058] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A cyclohexanone oxime rearrangement mixer structure, characterized by, The device includes a main structure (1), a ring sleeve (2), a cyclohexanone oxime inlet (3), and a cyclohexanone oxime orifice (4). The main structure (1) is a vertical structure with a circulating liquid inlet (11), a throat (13), and a mixture outlet (12) arranged sequentially from top to bottom. The circulating liquid containing caprolactam, sulfuric acid, and SO3 flows into the main structure (1) from the circulating liquid inlet (11). The ring sleeve (2) is fitted on the main structure (1) and is located between the circulating liquid inlet (11) and the throat (13). The cyclohexanone oxime inlet (3) is connected to the ring sleeve (2). The cyclohexanone oxime orifice (4) is arranged in a ring shape on the ring sleeve (2). After the cyclohexanone oxime enters the ring sleeve (2) through the cyclohexanone oxime inlet (3), it is sprayed into the circulating liquid through the cyclohexanone oxime orifice (4) and undergoes a rearrangement reaction.

2. The cyclohexanone oxime rearrangement mixer structure according to claim 1, wherein The cyclohexanone oxime orifice (4) is located within the negative pressure zone 0-15 mm above the throat (13) cross section.

3. The cyclohexanone oxime rearrangement mixer structure according to claim 1, wherein The diameter of the cyclohexanone oxime orifice (4) can be adjusted to 1-2 mm, and the expansion section angle of the main structure (1) is 40°-60°.

4. A numerical simulation calculation model, characterized in that, The cyclohexanone oxime rearrangement mixer as described in any one of claims 1-3 includes a physical model and a mathematical model; the physical model is a three-dimensional fluid domain model based on the geometry of the mixer, covering the entire fluid flow area from the circulating liquid inlet (11) to the mixture outlet (12), and is divided using an unstructured mesh, which includes triangular, quadrilateral, tetrahedral, hexahedral, pyramidal meshes or hybrid unstructured meshes; the mathematical model includes the Eulerian multiphase flow model and the Realizable k-ε turbulence model, used to simulate the momentum exchange, mixing process and turbulent flow characteristics of cyclohexanone oxime and circulating liquid in the mixer.

5. The numerical simulation calculation model according to claim 4, characterized in that, The governing equations of the mathematical model include the mass conservation equation, the momentum conservation equation, and the transport equations of the Realizable k-ε turbulence model.

6. The numerical simulation calculation model according to claim 4, characterized in that, The boundary conditions of the calculation model are set as follows: the circulating liquid inlet (11) and the cyclohexanone oxime inlet (3) are both velocity inlets, the mixture outlet (12) is a pressure outlet, and the inner wall of the main structure (1) adopts an adiabatic non-slip boundary.

7. An analytical method, characterized in that, Based on the numerical simulation calculation model as described in any one of claims 4-6, the following steps are included: S1: Import the physical property parameters of the circulating liquid and cyclohexanone oxime into the numerical simulation calculation model; S2: Using the controlled variable method, adjust the angle of the expansion section, the position of the cyclohexanone oxime orifice (4), the flow rate of the cyclohexanone oxime inlet (3), and the diameter of the cyclohexanone oxime orifice (4); S3: The pressure distribution, cyclohexanone oxime velocity distribution, and fluid motion trajectory within the mixer are obtained by solving the numerical simulation model; S4: Introduce momentum ratio (MR) as an evaluation index for mixing effect; S5: Based on the momentum ratio and flow field distribution results, analyze the mixing effect and equipment corrosion risk, and determine the optimal structural and operating parameters.

8. The analytical method according to claim 7, characterized in that, The adjustment range of the expansion section angle in S2 is 40°-60°, the adjustment range of the position of the cyclohexanone oxime orifice (4) is 0-15mm upward from the throat (13) section, the adjustment range of the flow rate of the cyclohexanone oxime inlet (3) is 12800-40000kg / h, and the adjustment range of the diameter of the cyclohexanone oxime orifice (4) is 1-3mm.

9. The analytical method according to claim 7, characterized in that, When the mixer structure and operating parameters remain unchanged, the change in jet parameters also affects the mixing effect. The flow velocity and jet area at the cyclohexanone oxime inlet (3) and the cyclohexanone oxime orifice (4) are determined based on the law of conservation of mass.

10. The analytical method according to claim 7, characterized in that, In S4, when MR < 1, it indicates that the momentum of the jet is insufficient and it is easily dispersed by the mainstream, resulting in low mixing efficiency; when MR > 4, it will cause the momentum of the jet to be too large, increasing the pressure loss. That is, the optimal structural parameters and operating parameters in S5 satisfy the momentum ratio MR being between 1 and 4.

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