Sulfuric acid alkylation reactor stirring optimization method based on fluid-solid coupling

Abstract

The invention provides a stirring optimization method for a sulfuric acid alkylation reactor based on fluid-solid coupling, which comprises the following steps: constructing a three-dimensional model of the alkylation reactor according to physical parameters of the alkylation reactor; optimizing the alkylation reactor three-dimensional model by combining a porous medium model and a fluid-solid coupling model to obtain an optimized alkylation reactor three-dimensional model; performing fluid simulation and transient stress simulation by using the optimized alkylation reactor three-dimensional model to obtain a simulation result; and optimizing the process parameters of the alkylation reactor according to the simulation result. According to the method disclosed by the invention, the reaction efficiency and stirring uniformity of the alkylation reactor are improved, the energy consumption is reduced, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of chemical equipment design, and in particular to a stirring optimization method for a sulfuric acid alkylation reactor based on fluid-solid coupling. Background Art

[0002] The alkylation reactor is the core equipment of the alkylation unit. During operation, problems such as hydraulic head shaft fracture, impeller cavitation, and internal component erosion and corrosion have occurred. In particular, hydraulic head shaft fracture has occurred frequently in multiple units, seriously affecting the long-term operation of the reactor. Since the fracture occurs at the root of the keyway, the fracture surface is a stress concentration area and the weakest point of the entire shaft. This is considered to be stress fatigue damage. Due to stress concentration and fatigue, cracks form. When the crack size reaches a critical size, a low-stress brittle fracture accident will occur. Consulting the technical data accompanying the equipment shows that the material selection and heat treatment are correct, the safety factor is high, and the strength fully meets the requirements. The fracture is a metal failure phenomenon under alternating stress.

[0003] The industry has analyzed the defects of hydraulic head shafts. However, since the operation of the hydraulic head is closely related to the internal flow field of the reactor, hydraulic shock, and the corrosive environment, the above-mentioned influencing factors were comprehensively considered to fundamentally explore the mechanism of hydraulic head fracture and failure. A solution for process and structural optimization was proposed to design a new reinforced agitator shaft based on the alkylation reaction. However, under high temperature, high pressure and highly corrosive environments, the agitator shaft is subjected to tremendous mechanical stress and chemical corrosion, resulting in fatigue, wear, and even fracture, which seriously affects the normal operation of the reactor, causing production interruptions and equipment damage. Therefore, how to improve the strength and corrosion resistance of the agitator shaft to prevent its fracture during the sulfuric acid alkylation reaction is an urgent problem to be solved.

[0004] Alkylation reactors are widely used in petrochemicals, fine chemical production, and other chemical synthesis processes. Especially under high temperature and pressure, reactants often require stirring to ensure reaction efficiency and uniformity. Due to the high reaction temperatures, strong corrosiveness, and high reactant viscosity, the agitator shaft is subject to very high stress and corrosion. Traditional agitator design methods rely primarily on single fluid dynamics or mechanical models, failing to fully consider the coupling between fluids and solids. Consequently, bottlenecks remain in optimizing reaction efficiency, increasing yields, and reducing energy consumption. Summary of the Invention

[0005] In view of this, the present invention provides a stirring optimization method for a sulfuric acid alkylation reactor based on fluid-solid coupling to solve the above problems.

[0006] The present invention provides a method for optimizing stirring of a sulfuric acid alkylation reactor based on fluid-solid coupling, comprising: constructing a three-dimensional model of the alkylation reactor according to physical parameters of the alkylation reactor; optimizing the three-dimensional model of the alkylation reactor by combining a porous medium model and a fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor; performing fluid simulation and transient stress simulation using the optimized three-dimensional model of the alkylation reactor to obtain simulation results; and optimizing process parameters of the alkylation reactor according to the simulation results.

[0007] In another embodiment of the present invention, the method further includes: meshing the three-dimensional model of the alkylation reactor, adjusting the range of the mesh in small areas, adjusting the boundary mesh at the boundaries or outer edges of the fitting parts, and adjusting the mesh of the large-sized cylinder and head.

[0008] In another embodiment of the present invention, optimizing the three-dimensional model of the alkylation reactor by combining the porous medium model and the fluid-solid coupling model to obtain the optimized three-dimensional model of the alkylation reactor includes: simplifying the heat exchange tube bundle structure in the three-dimensional model of the alkylation reactor by using the porous medium model; and optimizing the flow field distribution in the three-dimensional model of the alkylation reactor by using the fluid-solid coupling model to obtain the optimized three-dimensional model of the alkylation reactor.

[0009] In another implementation of the present invention, the method further includes calculating the viscous resistance, inertial resistance, porosity, and relative viscosity of the fluid in the heat exchange tube bundle in combination with the law of conservation of energy, and substituting these into the porous area properties in the simplified heat exchange tube bundle structure to simulate the physical properties and mass transfer effects of the heat exchange tube bundle in fluid motion.

[0010] In another implementation of the present invention, the energy conservation law includes the porous media mass conservation law, the porous media momentum conservation law and the porous media energy conservation law.

[0011] In another implementation of the present invention, the fluid simulation is performed based on a k-ε turbulence model, and the flow field distribution, driving torque, and power consumption are analyzed according to the simulation results.

[0012] In another implementation of the present invention, the transient stress simulation calculates the stress, deformation, and vibration mode of the stirring system by mapping the fluid load to the structural grid.

[0013] Another aspect of the present invention provides a sulfuric acid alkylation reactor stirring optimization system based on fluid-solid coupling, comprising: a model construction module for constructing a three-dimensional model of the alkylation reactor based on the physical parameters of the alkylation reactor; a model optimization module for optimizing the three-dimensional model of the alkylation reactor by combining a porous medium model and a fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor; a simulation module for performing fluid simulation and transient stress simulation using the optimized three-dimensional model of the alkylation reactor to obtain simulation results; and a parameter optimization module for optimizing the process parameters of the alkylation reactor based on the simulation results.

[0014] In another aspect of the present invention, an electronic device is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method for optimizing stirring of a sulfuric acid alkylation reactor based on fluid-solid coupling as described above are implemented.

[0015] Another aspect of the present invention provides a computer storage medium, characterized in that a computer program is stored on the computer storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned method for optimizing stirring of a sulfuric acid alkylation reactor based on fluid-solid coupling are implemented.

[0016] The present invention's stirring optimization method for a sulfuric acid alkylation reactor based on fluid-solid coupling employs fluid-solid coupling simulation and a porous media model, combining the characteristics of fluid-solid coupling, fluid mechanics, and solid mechanics. This method can more accurately simulate and optimize the material flow and stirring effects in the reactor, significantly improving stirring efficiency and heat and mass transfer during the reaction process, particularly when dealing with complex reaction systems and multiphase flows. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. By reading the detailed description of the embodiments below, the advantages and benefits of the solutions will become clear to those skilled in the art. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. In the drawings:

[0018] Figure 1 The figure is a schematic flow chart of a stirring optimization method for a sulfuric acid alkylation reactor based on fluid-solid coupling according to an embodiment of the present invention.

[0019] Figure 2 This is a general assembly diagram of an alkylation reactor according to an embodiment of the present invention.

[0020] Figure 3This is a simplified before-and-after comparison diagram of a heat exchange tube bundle model according to an embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the FLUENT fluid-solid coupling process according to an embodiment of the present invention.

[0022] Figure 5 Schematic diagram of the fluid-structure coupling process according to an embodiment of the present invention.

[0023] Figure 6 Schematic diagram comparing pressure nephograms before and after fluid-solid coupling optimization according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and detailedly described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0025] Figure 1 A schematic flow chart of a stirring optimization method for a sulfuric acid alkylation reactor based on fluid-solid coupling is provided in an embodiment of the present invention. Figure 1 As shown, this embodiment mainly includes:

[0026] S101. Construct a three-dimensional model of the alkylation reactor based on the physical parameters of the alkylation reactor.

[0027] S102. Optimizing the three-dimensional model of the alkylation reactor by combining the porous medium model and the fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor.

[0028] S103 , using the optimized three-dimensional model of the alkylation reactor to perform fluid simulation and transient stress simulation to obtain simulation results.

[0029] S104: Optimize the process parameters of the alkylation reactor according to the simulation results.

[0030] The present invention's stirring optimization method for a sulfuric acid alkylation reactor based on fluid-solid coupling employs fluid-solid coupling simulation and a porous media model, combining the characteristics of fluid-solid coupling, fluid mechanics, and solid mechanics. This method can more accurately simulate and optimize the material flow and stirring effects in the reactor, significantly improving stirring efficiency and heat and mass transfer during the reaction process, particularly when dealing with complex reaction systems and multiphase flows.

[0031] In another embodiment of the present invention, the method further includes: meshing the three-dimensional model of the alkylation reactor, adjusting the range of the mesh in small areas, adjusting the boundary mesh at the boundaries or outer edges of the fitting parts, and adjusting the mesh of the large-sized cylinder and head.

[0032] For example, Figure 2 As shown, a three-dimensional model is established based on the alkylation reactor equipment, wherein 1-cooling water inlet, 2-cooling water outlet, 3-reactant outlet, 4-heat exchange tube bundle, 5-acid inlet, 6-raw material inlet, 7-stirring blade, 8-segmented shaft, and 9-motor.

[0033] First, measure and determine the various parameters mentioned above. Then, use modeling software (such as SolidWorks) to construct a three-dimensional geometric model. Construct the agitator blades, agitator shaft, reinforcement ribs, inner sleeve and outer sleeve of the alkylation reactor, as well as the catalyst inlet and outlet, raw material inlet and outlet, and shaft sleeve according to the actual size and shape, and mesh the model.

[0034] Because the alkylation reactor combines a heat exchange section on one side and a stirring section on the other, it can achieve both heat exchange and stirring reactions. However, its internal structure and boundaries are complex, resulting in numerous tiny, fine areas that can lead to low orthogonal quality during meshing. This can cause errors or inaccurate calculated data during subsequent fluid-structure interaction simulations. Therefore, special processing must be performed on these various mesh components.

[0035] Specifically, the mesh of relatively small areas such as stirring blades, stirring shafts, bearings, and raw material inlets and outlets is adjusted (1-5mm) to increase the fineness of the mesh and improve the quality of the mesh.

[0036] Edge mesh adjustments are performed on certain edge areas. Due to the complex internal structure of the alkylation reactor, most of the components are usually completed by fitting together. This may cause the boundaries of the fitting parts or the boundaries of the outer edges to fail or the mesh cannot be correctly divided. In addition, there are internal structures that need to be extended, such as the inlet and outlet pipes of the raw materials and acid. In order to fully stir the pipes, the pipes will be extended to the stirring blades. Therefore, the above areas need to adjust the boundary mesh to meet the simulation requirements and reduce the failed mesh area.

[0037] Mesh adjustments were made to some large-sized cylinders and heads. Since the alkylation reactor is too large, its length reaches 12573.0 mm and its width reaches 2352.7 mm, as shown in the alkylation reactor drawings. Therefore, its mesh could not be adjusted according to the pre-defined dimensions, which would result in an excessive number of meshes and an increase in the computational complexity. Therefore, the meshes of the outer and inner circulation cylinders of the alkylation reactor were adjusted (in the range of 10 mm to 20 mm), and finally the meshing of the entire alkylation reactor was completed.

[0038] In another embodiment of the present invention, optimizing the three-dimensional model of the alkylation reactor by combining the porous medium model and the fluid-solid coupling model to obtain the optimized three-dimensional model of the alkylation reactor includes: simplifying the heat exchange tube bundle structure in the three-dimensional model of the alkylation reactor by using the porous medium model; and optimizing the flow field distribution in the three-dimensional model of the alkylation reactor by using the fluid-solid coupling model to obtain the optimized three-dimensional model of the alkylation reactor.

[0039] For example, due to the complex internal structure of the alkylation reactor, including the internal circulation of the inner shell, the external circulation of the outer shell, and the heat exchange tube bundle at the left end that cools the exothermic alkylation reaction, the cooling of the heat exchange tube bundle is also a very important part. However, the internal heat exchange tube bundle has a total of 613 tubes, which complete the cooling of the chemical reaction within the alkylation reactor. Meshing this would result in an excessively large number of cells and low orthogonal quality, making it impossible to successfully complete the fluid-solid coupled heat exchange component in the simulation software (Fluent is used as an example in this article). Therefore, in order to simplify it, a porous medium model is introduced.

[0040] Porous media refers to porous composite media composed of multiple substances in a certain space. In porous media, solid media constitute the skeleton, and other non-solid areas are called pores and are occupied by fluid. It is currently widely used in the study of the flow laws of fluids in solid media and fluid-solid coupled heat transfer and other fields related to fluid mechanics.

[0041] A porous media model was used to scale up the alkylation reactor. By simplifying the complex heat exchange tube bundle system into a medium with a certain porosity, the computational complexity can be reduced. This simplification makes the solution process more efficient, especially when complex situations involving fluid flow and heat transfer are involved, avoiding the need to calculate each tube individually. Fluid flow in a heat exchange tube bundle can be affected by factors such as tube arrangement, flow resistance, and local turbulence. By using a porous media model, the distribution and flow characteristics of the fluid in the tube bundle can be better simulated. This provides more accurate results than a single-tube model, especially for studying local flow and heat transfer mechanisms.

[0042] like Figure 3 The figure below shows a comparison of the heat exchanger bundle before and after simplification. First, a simplified model of the heat exchanger bundle is created. The bundle is removed, leaving only the cooling water inlet and outlet, flange, and heat exchange area. The model is then remodeled. The entire model is created by removing the small bundles to reflect the overall flow state. This model is then imported into Fluent to set porous regions. The calculated parameters are then set to simulate the actual flow conditions within the bundle, ultimately completing the creation of the porous region within the bundle.

[0043] The purpose is to reduce the large number of small structural units, such as pores and channels, that are typically contained in heat exchange tube bundles. By establishing a detailed porous media model, the geometry and physical processes of the pores can be better captured, avoiding the loss of important physical information due to overly coarse meshes, thereby improving the accuracy of numerical simulations.

[0044] It should be understood that fluid-solid coupling refers to the interaction between fluids and solids. In alkylation reactions, catalyst particles are often used, so a fluid-solid coupling model is needed to simulate the interaction between the fluid and solids. Using a combination of computational fluid dynamics (CFD) and finite element analysis (FEA), a coupling model is constructed between the fluid flow and the solid agitator in the alkylation reactor. This model simultaneously accounts for the interaction between the fluid and solids, particularly the coupling effects in multiphase flow environments (such as gas-liquid-solid).

[0045] The pressure exerted by the fluid on the agitator shaft during the fluid simulation is output and transmitted to the transient stress simulation, which calculates the deformation of the agitator shaft under different stress conditions. This deformation is then output back to the fluid simulation to observe the changes in the fluid domain. This iterative process achieves bidirectional fluid-structure coupling for the agitator shaft. In short, this is achieved through the coupling between the fluid domain simulation analysis in Fluent and the agitator shaft simulation analysis in Transient Structure.

[0046] By combining porous media with a fluid-structure interaction model, the flow field distribution within the reactor is optimized using the fluid-structure interaction model, ensuring uniform distribution of fluid and solid particles within the reactor. This is particularly true at the reactor bottom and around the agitator. By adjusting the flow rate and direction, dead zones and localized overflow areas are reduced, achieving uniform mixing. The porous media is utilized to optimize the reactor's thermal management scheme, ensuring uniform temperature distribution within the reactor and preventing localized overheating or low-temperature areas from impacting reaction efficiency. The optimized design reduces stirring power and heat exchange power consumption, minimizing reactor energy losses. By precisely controlling the reaction temperature and time, the reaction conversion rate and selectivity are maximized.

[0047] Compared with traditional design methods, the present invention accurately captures the interaction between fluids, solid structures and porous media through numerical simulation, can provide more accurate data support for reactor design, optimize the design of the stirring device and heat exchange system, reduce energy consumption, and improve the operational stability of the reactor.

[0048] In another implementation of the present invention, the method further includes calculating the viscous resistance, inertial resistance, porosity, and relative viscosity of the fluid in the heat exchange tube bundle in combination with the law of conservation of energy, and substituting these into the porous area properties in the simplified heat exchange tube bundle structure to simulate the physical properties and mass transfer effects of the heat exchange tube bundle in fluid motion.

[0049] For example, the viscous and inertial drag within the heat exchange tube bundle, as well as the porosity and relative viscosity of the fluid, are calculated to simulate the physical properties and mass transfer effects of the heat exchange tube bundle during fluid movement. Since there are 613 heat exchange tube bundles, it's impossible to calculate each one. However, their internal structural characteristics and curvature are generally consistent. Therefore, a single tube bundle at the center is selected for calculation to simulate the average mass transfer and flow effects within each heat exchange tube bundle.

[0050] By simulating a single heat exchange tube bundle, the center of the 613 tube bundles was selected to represent the average parameters of each tube. By setting the boundary conditions of the selected single heat exchange tube bundle, the inlet velocity was temporarily set to 1m / s and the outlet pressure p2 = 2000pa for simulation. When using CFD numerical simulation for porous media models, continuous incompressible fluids satisfy the three major conservation laws: the law of conservation of porous media energy, the law of conservation of porous media momentum, and the law of conservation of porous media energy. According to the pressure cloud map of the simulation results, the area average pressure of the output and inlet was set in the results to obtain p1, and finally △p = |p1-p2| was obtained.

[0051] By selecting an appropriate range of outlet and inlet pressures and performing the aforementioned multi-component simulation, a curve is generated relating Δp and v. Finally, the coefficients a and b are solved by fitting the resulting equation. This equation prepares the subsequent calculation of the viscosity and inertial drag coefficients for a single heat exchange tube bundle.

[0052] When setting up the porous media area in simulation software (such as ANSYS Fluent), it is necessary to define its viscous resistance coefficient and inertial resistance coefficient. Both coefficients can be calculated using the semi-empirical Ergun formula. When the bed fluid maintains a laminar state, the formulas are shown in Equations 1-1 and 1-2.

[0053] Viscous drag coefficient:

[0054]

[0055] Inertial drag coefficient:

[0056]

[0057] Among them, D p is the equivalent diameter of the solid medium, m.

[0058] In addition to the viscosity coefficient and resistance coefficient, porosity is also one of the important indicators for simulating the actual working conditions inside the heat exchange tube bundle. Porosity ε refers to the percentage of pore volume in the porous medium space to the total volume. It is an important parameter to characterize the porosity of the porous medium. Its expression is as follows:

[0059]

[0060] Among them, V k is the pore volume in the porous medium, m3, which is the volume of the shell-side flow field excluding the sleeve in this model; V z is the total volume of the porous medium, m3.

[0061] In another implementation of the present invention, the energy conservation law includes the porous media mass conservation law, the porous media momentum conservation law and the porous media energy conservation law.

[0062] For example, when using CFD numerical simulation for a porous media model, the continuous incompressible fluid satisfies three conservation laws, as follows:

[0063] Mass conservation law for porous media:

[0064]

[0065] Momentum conservation law for porous media:

[0066]

[0067] Energy conservation law of porous media:

[0068]

[0069] By following the above formulas and the three energy conservation laws, the viscous resistance coefficient, inertial resistance coefficient, and porosity are obtained and substituted into the porous area properties in the simplified heat exchange tube bundle to facilitate subsequent simulation of fluid-solid coupling.

[0070] The porous media model was meshed using a tetrahedral unstructured grid in ANSYS ICEM, and its mesh independence was verified. The final total number of mesh elements in the model was determined to be 182,754, a 73.1% reduction in mesh size compared to the original model.

[0071] A porous media model was used to simplify the heat exchange tube bundle structure of the alkylation reactor's characteristic model. The simplified model reduced the heat transfer coefficient by 3.4% and increased the shell-side pressure drop by 4.6%, with an error within 5%, demonstrating the feasibility of using a porous media model for simplification. This simplified approach was then used to establish a porous media integrated model and perform numerical simulations. The results showed that compared to the porous media characteristic model, the integrated model's heat transfer coefficient decreased by 8.72% and the shell-side pressure drop increased by 6.97%, with an error of approximately 10%, demonstrating the feasibility of using a porous media model for studying alkylation reactors.

[0072] In another implementation of the present invention, the fluid simulation is performed based on a k-ε turbulence model, and the flow field distribution, driving torque, and power consumption are analyzed according to the simulation results.

[0073] For example, Figure 4 and Figure 5 As shown, fluid-structure interaction (FSI) is performed on the alkylation reactor equipment, including Ansys impeller passive rotation and fluid-structure interaction (Fluent+Transient Structure) simulation analysis and fluid impact blade simulation (FSI) on the agitator shaft. The pressure exerted by the fluid on the agitator shaft during FSI is output and transmitted to the transient stress simulation, which calculates the deformation of the agitator shaft under different stress conditions. This deformation is then output back to the fluid simulation to observe changes in the fluid region. This iterative process achieves bidirectional FSI for the agitator shaft.

[0074] When it comes to system coupling, coupling equations are involved. The fluid-solid interface equations take into account equilibrium and compatibility conditions, namely, conservation conditions such as stress δ, displacement d, heat flux q, and temperature T of the fluid and solid.

[0075] δ nf =δ ns

[0076] d f =d s

[0077] q f =q s

[0078] T f =T s

[0079] Where the subscripts f and s refer to fluid and solid, respectively; n is the normal vector.

[0080] Solid mechanics equations, solid control equations are linear static analysis equations:

[0081] [k]{x}={F}

[0082] Where: [K]—stiffness matrix; {x}—displacement; {F}—load vector.

[0083] In the solution process, any form of fluid motion must adhere to the three fundamental conservation laws: conservation of mass, conservation of momentum, and conservation of energy. These laws serve as the foundation for discussion, analysis, and calculation of practical motion problems. In a three-dimensional coordinate system, the Euler method is used to describe the motion of fluid particles in the flow field. The three equations are shown below.

[0084] The continuity equation is essentially the mass conservation equation, which is the specific embodiment of the law of conservation of matter in fluid mechanics. Its differential equation is as follows:

[0085]

[0086] Where ρ is the density, and u, v, and ω are the vector components of velocity in the X, Y, and Z directions. If ρ is a constant, that is, the fluid is incompressible, substituting it into equation (1-9) and rearranging it yields the following differential equation:

[0087] If ρ does not change with time, that is, the fluid flow is in a steady state, after sorting out equation (1-9), the continuity differential equation for the fluid flow in a steady state is:

[0088]

[0089] Where ρ is the density, and u, v, and ω are the vector components of the velocity in the X, Y, and Z directions.

[0090] The law of conservation of momentum is actually Newton's second law, and the momentum equation is also called the SN equation. The SN differential equations for the X, Y, and Z directions are as follows:

[0091]

[0092] Where, f x , f y , f z represents the mass force on the fluid element in the X, Y, and Z axes, 2m / s; P is the pressure on the element, pa; μ is the dynamic viscosity of the fluid, spa; v x , v y , v z represents the fluid velocity v in the X, Y, and Z axes, m / s. If the fluid is incompressible, substitute equation (1-10) into equation (1-11) and introduce the Laplace operator. After sorting, the SN-differential equation for incompressible fluid is:

[0093]

[0094] The N-equation is a differential equation of universal significance in fluid mechanics. Almost every fluid flow problem is solved by solving the SN-differential equation, but it is only applicable to Newtonian fluids and is applicable to real flow fields in laminar or turbulent states.

[0095] The energy equation is essentially the first law of thermodynamics, which must be followed for any flow system involving heat exchange. The energy equation is expressed as:

[0096]

[0097] Where E is the energy of the fluid, J / kg; h is the enthalpy, J / kg; h j is the enthalpy of component j, J / kg; k e is the effective heat transfer coefficient, W / (m 2 ·K); J j is the diffusion flux of component j; S h is the volumetric heat source term. It should be noted that while Equation (1-13) is the fundamental governing equation for flow systems involving heat exchange, it applies only to Newtonian fluids. If the amount of heat exchange is negligibly small when solving a flow problem where ρ is a constant, the use of Equation (1-13) can be disregarded, and the incompressible fluid flow problem can be solved simply by combining Equations (1-10) and (1-12).

[0098] In the FLUENT simulation calculation, the RNGK-ε turbulence model was selected with reference to different literatures, and the RNGK-ε model was also used in the calculation. The fluid velocity between the plates was very low, and the fluid motion form was not fully developed. The local curvature of the geometric model was high. In order to obtain high calculation accuracy and combine it with the wall function method, this model was selected for calculation simulation based on the above calculations and rationality.

[0099] Using ANSYS Fluent, we analyzed the flow field distribution, driving torque, and power consumption based on the k-ε turbulence model. The entire alkylation reaction equipment was imported into Fluent and configured, and fluid-solid coupling was performed to investigate the effects of the internal flow field dynamics on the agitator shaft. The model used was Realizable in the k-epsilon (2eqn) model, and the enhanced wall function (EWF) was used as the wall function. An interface was created between the moving domain and the stationary domain. In Fluent, this interface was created and named using the Mesh→Interfaces menu. The moving domain was selected, and in the Cell Zone Conditions, MeshMotion was set to -X and 0.3 m / s.

[0100] To improve the stirring effect, the stirring shaft of the present invention is equipped with spiral stirring blades of a specific shape and angle. Through Fluent simulation, it can be concluded that the spiral blades can produce stronger fluid disturbances, which helps to improve the mixing efficiency of the reactants and reduce the excessive load on the stirring shaft caused by high viscosity, thereby reducing the risk of shaft breakage. A reasonable stirring device design is adopted to ensure the uniformity of flow inside the reactor, reduce the consumption of stirring power, and improve the heat exchange effect. According to the simulation results, the speed of the stirrer, the shape and arrangement of the stirring blades are adjusted to ensure optimal flow conditions and maximize the reaction rate and product selectivity.

[0101] In another implementation of the present invention, the transient stress simulation calculates the stress, deformation, and vibration mode of the stirring system by mapping the fluid load to the structural grid.

[0102] For example, the fluid load (pressure, turbulent kinetic energy) is mapped to the structural grid through the ANSYS Static Structural module to calculate the stress, deformation and vibration mode of the stirring system.

[0103] In the Fluent+Transient Structure simulation analysis, the fluid region in the transient structure is suppressed, and only the stress analysis of the solid part is considered. The material 42CrMo is set as the material of the rotor shaft. Conversely, for the geometric structure in Fluent, the solid region is suppressed, only the flow of the fluid domain is considered, and a fanwall is set. Finally, they are meshed and the models are imported into the transient structure and fluid flow (Fluent) respectively.

[0104] Boundary condition setting: Boundary conditions need to be set before simulation, the temperature of the raw material inlet and the reaction cavity circulation of the alkylation reaction equipment, the fluid addition raw materials, catalyst and stirring shaft raw materials are set.

[0105] Transient structure settings: Add standard earth gravity to its agitator shaft; set fixed support for its bearings; set the fluid-solid interface; add a connecting sub-hinge and set the rotation speed to 2950r / min to simulate actual operating conditions. Through the above settings, the agitator shaft can rotate in the fluid-solid coupling.

[0106] Fluid flow (Fluent) settings: mainly the settings of its materials; inlet and outlet settings: all are set as pressure inlets and outlets; dynamic mesh settings re-divide the dynamic mesh of its fan-wall area; set the stirring shaft pressure cloud map and ZX-plane to facilitate the observation of subsequent force analysis results.

[0107] The alkylation reaction equipment was imported into Fluent and set up. The CFD model and wall function were selected. The pressure-velocity coupling solution was adopted. Then, its transient structure was coupled with the Fluent system. Two different time steps of 0.001 and 0.0003 were selected for the analysis settings. The fluid-solid interface and fan wall were coupled together for data transmission and finally the solution was obtained.

[0108] Create an interface between the moving domain and the stationary domain. In Fluent, create and name the interface through the Mesh→Interfaces menu. Select the moving domain and set MeshMotion, movement direction, and speed in CellZoneConditions. Perform fluid-solid coupling on the internal flow field of the alkylation reactor. Set the dynamic mesh to enable the stirring shaft to operate in the simulation and calculate the equivalent stress and total deformation it is subjected to.

[0109] The maximum and minimum pressure distributions show that the blade surface is the point of maximum pressure, which explains why the cracks and surface wear are caused not only by the corrosiveness of the reactants but also in part by the pressure. The blades and the agitator shaft are fixed in a cylindrical manner, which means that the lateral force on the agitator shaft mainly comes from the deformation of the blades. The stress cloud diagram of the agitator shaft shows that the stress changes are relatively uniform throughout the agitator shaft, with no obvious stress mutations or stress concentrations. The maximum stress is not enough to cause the agitator shaft to break, so the failure of the agitator shaft due to excessive stress can be ruled out. Therefore, considering that the fracture of the agitator shaft is related to the vibration characteristics of the agitator, it may be due to the operating speed being too close to its resonant frequency, which causes excessive vibration. Finally, the total transient structural deformation is solved, and it can be clearly seen that the strength of the agitator shaft has been significantly improved, reducing the stress concentration of the agitator shaft.

[0110] Based on the simulation of fluid impact on the stirring blade (fluid-solid coupling) of its stirring shaft, the velocity streamline diagram and velocity vector diagram were obtained. It can be observed that the velocity of the fluid suddenly increases after passing through the stirring blade, which may cause fatigue brittle fracture at the other end of its stirring shaft.

[0111] In another implementation of the present invention, the reactor's process parameters, including feed flow rate, agitator speed, temperature, and pressure, are optimized based on simulation results from fluid-structure interaction and porous media models. Adjusting these parameters can effectively improve the reactor's reaction conversion rate, reduce energy consumption, and extend the equipment's service life.

[0112] Velocity distribution: Velocity distribution significantly influences reaction rates and heat transfer within the reactor. By optimizing the flow pattern within the reactor, we can avoid localized excess or sub-zero velocities that can lead to uneven reactions or inefficient heat transfer. Fluid-structure interaction models are typically used to simulate the interaction between the fluid and the reactor walls to improve flow uniformity.

[0113] Turbulence and laminar flow management: In alkylation reactors, fluids often transition between turbulent and laminar flow. The turbulent characteristics of the fluid directly affect the suspension and mixing of catalyst particles. Fluid-structure interaction analysis can optimize the turbulent flow structure within the reactor, maintaining a turbulent state for the majority of the fluid, ensuring sufficient contact between reactants and catalysts, and ultimately improving reaction rate, heat transfer efficiency, and selectivity.

[0114] Local flow optimization: By adjusting parameters such as cooling water flow paths and flow rates, local overheating or heat loss can be avoided while ensuring efficient heat exchange. Fluid-structure interaction models can help analyze the optimization space for these local flows and heat exchange.

[0115] Thermal Management Optimization: In alkylation reactions, temperature significantly impacts the reaction. The heat released during the reaction needs to be effectively managed and recovered to reduce external energy requirements. By optimizing the reactor's heat transfer efficiency and material flow through fluid-solid coupling, we ensure the reaction proceeds at the optimal temperature and avoid temperature variations that can reduce reaction efficiency, thereby reducing energy consumption and maximizing reaction efficiency.

[0116] Cooling system optimization: Optimizing the cooling water flow path, flow rate, and temperature is not only crucial for reactor temperature control but also closely linked to energy conservation and reduced operating costs. Fluid-structure interaction analysis can identify optimization opportunities in cooling water flow, improving cooling efficiency and reducing energy waste.

[0117] Constraint Selection: Single-span constraints are superior to cantilever constraints in reducing main shaft stress and deformation, with the maximum main shaft stress being only 62% of that of cantilever constraints. Blade Design: Stress concentration points typically occur at the connection between the blade and the disc, requiring geometric optimization (such as fillet design and material strengthening) to reduce local stress. Flow Disturbance Control: The k-ε turbulence model is used to optimize the flow field distribution, reduce vibration caused by eddies, and thus mitigate the risk of structural fatigue.

[0118] like Figure 6As shown, key parameters and internal flow fields have been significantly improved compared to those before and after optimization and improvement. By optimizing the propeller blade shape and the segmented design of the stirring shaft, the reactants can be stirred more evenly, promoting contact between the reactants and the catalyst and improving reaction efficiency. By optimizing the flow field distribution, dead zones and uneven flow are reduced, improving mixing and mass transfer efficiency within the reactor. For example, this results in increased yield, quality, precision, and efficiency; savings in energy consumption, raw materials, and process steps; simplified processing, operation, control, and use; and reduced or eradicated environmental pollution.

[0119] The present invention relates to agitation optimization technology for alkylation reactors. By optimizing the internal flow field and agitation design of the reactor through fluid-solid coupling, the reaction efficiency and product quality of the alkylation reactor can be significantly improved. Utilizing CFD simulation and fluid-solid coupling analysis techniques, a deep understanding of the flow and particle interactions within the reactor can be achieved, optimizing key factors such as fluid distribution, agitation effect, and particle distribution, thereby improving reaction efficiency, reducing energy consumption, and minimizing catalyst loss and wear. By optimizing the design and operating parameters of the agitator, this method not only improves the reaction efficiency of the alkylation reaction, but also significantly reduces energy consumption and enhances the stability and reliability of the equipment. This technical solution is applicable to alkylation reactions and other similar chemical reaction processes and can be widely used in the petrochemical industry and other chemical reaction fields requiring efficient agitation.

[0120] Another aspect of the present invention provides a sulfuric acid alkylation reactor stirring optimization system based on fluid-solid coupling, comprising:

[0121] Model building module: Construct a three-dimensional model of the alkylation reactor based on the physical parameters of the alkylation reactor.

[0122] Model optimization module: optimizes the three-dimensional model of the alkylation reactor by combining the porous medium model and the fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor.

[0123] Simulation module: using the optimized three-dimensional model of the alkylation reactor to perform fluid simulation and transient stress simulation to obtain simulation results.

[0124] Parameter optimization module: optimizes the process parameters of the alkylation reactor according to the simulation results.

[0125] Another aspect of the present invention provides a sulfuric acid alkylation reactor stirring optimization system based on fluid-solid coupling, comprising:

[0126] The present invention's fluid-solid coupling-based sulfuric acid alkylation reactor stirring optimization system utilizes fluid-solid coupling simulation and a porous media model, combining the characteristics of fluid-solid coupling, fluid mechanics, and solid mechanics. This system can more accurately simulate and optimize the material flow and stirring effects in the reactor, significantly improving stirring efficiency and heat and mass transfer during the reaction process, particularly when dealing with complex reaction systems and multiphase flows.

[0127] In another aspect of the present invention, an electronic device includes a processor, a memory, a communication bus, and a communication interface.

[0128] in:

[0129] The processor, memory and communication interface communicate with each other through a communication bus.

[0130] Communication interface, used to communicate with other electronic devices or servers.

[0131] The processor is used to execute the program, and specifically can execute the steps of any one of the above-mentioned embodiments of the method for optimizing stirring of a sulfuric acid alkylation reactor based on fluid-solid coupling.

[0132] Specifically, the program may include program codes including computer operation instructions.

[0133] The processor may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application. The one or more processors included in the smart device may be processors of the same type, such as one or more CPUs; or different types of processors, such as one or more CPUs and one or more ASICs.

[0134] Memory is used to store programs. The memory may include high-speed RAM memory, and may also include non-volatile memory (non-volatile memory), such as at least one disk storage.

[0135] The program can be specifically configured to cause a processor to execute the steps of any of the fluid-solid coupling-based methods for optimizing agitation in a sulfuric acid alkylation reactor described in the embodiments. The specific implementation of each step in the program can be found in the corresponding descriptions of the steps and units executed in any of the aforementioned methods for optimizing agitation in a sulfuric acid alkylation reactor based on fluid-solid coupling, and will not be repeated here. Those skilled in the art will clearly understand that, for ease and brevity of description, the specific operating processes of the devices and modules described above can be referenced to the corresponding process descriptions in the aforementioned method embodiments.

[0136] The exemplary embodiments of the present application further provide a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable a computer to execute the methods of the various embodiments of the present application.

[0137] The method according to the embodiment of the present invention described above can be implemented in hardware, firmware, or as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or as computer code that is originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded via a network and will be stored in a local recording medium, so that the method described herein can be stored in such software processing on a recording medium using a general-purpose computer, a dedicated processor or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component (e.g., RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by a computer, a processor or hardware, the method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown here, the execution of the code converts the general-purpose computer into a dedicated computer for executing the method shown here.

[0138] Thus far, specific embodiments of the present invention have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired results. Additionally, the processes depicted in the accompanying drawings do not necessarily require the specific order shown, or sequential order, to achieve the desired results.

[0139] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, back, etc.) are only used to explain the relative position relationship between the components in a certain specific order (as shown in the accompanying drawings). If the specific order changes, the directional indication will also change accordingly.

[0140] In the description of the present invention, the terms "first" and "second" are used solely to facilitate description of different components or names and should not be construed as indicating or implying a sequential relationship, relative importance, or implicitly specifying the quantity of the technical features being described. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of such features.

[0141] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0142] It should be noted that although the specific embodiments of the present invention are described in detail in conjunction with the accompanying drawings, this should not be construed as limiting the scope of protection of the present invention. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative effort still fall within the scope of protection of the present invention.

[0143] The examples of the embodiments of the present invention are intended to briefly illustrate the technical features of the embodiments of the present invention so that those skilled in the art can intuitively understand the technical features of the embodiments of the present invention, and are not intended to improperly limit the embodiments of the present invention.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for optimizing stirring of a sulfuric acid alkylation reactor based on fluid-solid coupling, characterized in that: include: According to the physical parameters of the alkylation reactor, a three-dimensional model of the alkylation reactor is constructed; Optimizing the three-dimensional model of the alkylation reactor by combining a porous medium model and a fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor; Using the optimized three-dimensional model of the alkylation reactor, fluid simulation and transient stress simulation are performed to obtain simulation results; According to the simulation results, the process parameters of the alkylation reactor are optimized.

2. The method according to claim 1, characterized in that Also includes: The three-dimensional model of the alkylation reactor is meshed, the range of the mesh in the small area is adjusted, the boundary mesh of the boundary or outer edge of each part is adjusted, and the mesh of the large-sized cylinder and head is adjusted.

3. The method according to claim 1, characterized in that The three-dimensional model of the alkylation reactor is optimized by combining the porous medium model and the fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor, including: A porous media model is used to simplify the heat exchange tube bundle structure in the three-dimensional model of the alkylation reactor; The flow field distribution in the three-dimensional model of the alkylation reactor is optimized using a fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor.

4. The method according to claim 3, characterized in that Also includes: The viscous resistance, inertial resistance, porosity, and relative viscosity of the fluid in the heat exchange tube bundle are calculated in conjunction with the law of conservation of energy. These properties are then substituted into the porous region properties of the simplified heat exchange tube bundle structure to simulate the physical characteristics and mass transfer effects of the heat exchange tube bundle in fluid motion.

5. The method according to claim 4, characterized in that The energy conservation law includes the porous medium mass conservation law, the porous medium momentum conservation law and the porous medium energy conservation law.

6. The method according to claim 1, characterized in that The fluid simulation is performed based on the k-ε turbulence model, and the flow field distribution, driving torque and power consumption are analyzed according to the simulation results.

7. The method according to claim 6, characterized in that The transient stress simulation calculates the stress, deformation, and vibration modes of the stirring system by mapping the fluid load to the structural mesh.

8. A sulfuric acid alkylation reactor stirring optimization system based on fluid-solid coupling, characterized in that: include: Model building module: constructs a three-dimensional model of the alkylation reactor based on the physical parameters of the alkylation reactor; Model optimization module: optimizing the three-dimensional model of the alkylation reactor by combining the porous medium model and the fluid-solid coupling model to obtain an optimized three-dimensional model of the alkylation reactor; Simulation module: using the optimized three-dimensional model of the alkylation reactor to perform fluid simulation and transient stress simulation to obtain simulation results; Parameter optimization module: optimizes the process parameters of the alkylation reactor according to the simulation results.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of a method for optimizing stirring of a sulfuric acid alkylation reactor based on fluid-solid coupling are implemented as described in any one of claims 1 to 7.

10. A computer storage medium, characterized in that The computer storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for optimizing stirring of a sulfuric acid alkylation reactor based on fluid-solid coupling according to any one of claims 1 to 7.

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