A high-toughness and corrosion-resistant SiC-based composite distillation column structure and its design method

Abstract

This invention discloses a high-toughness and corrosion-resistant SiC-based composite distillation column structure and its design method. The composite distillation column structure consists of multiple layers of SiC-based composite material and an outermost SiC coating. The SiC-based composite material is composed of a C fiber preform and a SiC ceramic matrix covering the C fiber preform. The volume fraction of the single-layer C fiber preform gradually increases from the inner layer to the outer layer of the distillation column. The design method is as follows: a. Determine the number of braided layers of the composite distillation column, the fiber volume fraction of each layer, and the fiber braiding angle; b. Establish single-layer composite distillation columns with different inner diameters; c. Establish a multi-layer composite distillation column with a SiC coating; d. Calculate the tensile strength of the multi-layer composite distillation column. The multi-layer SiC-based composite distillation column designed in this invention has the characteristics of corrosion resistance, high strength, and high toughness, compensating for the insufficient toughness of high-purity SiC ceramic distillation columns and achieving performance optimization of ceramic-based distillation columns.

Description

Technical Field

[0001] This invention relates to the field of distillation column technology in the separation, purification and synthesis of chemical industry, and specifically provides a high-toughness and corrosion-resistant SiC-based composite distillation column structure and its design method. Background Technology

[0002] In many key areas of modern industry, such as chemical, petroleum, pharmaceutical and energy, distillation columns are one of the core pieces of equipment. Their mechanical properties have a significant impact on the safety, stability and durability of the entire production system. However, traditional distillation columns have many problems in terms of mechanical properties that urgently need to be solved.

[0003] From a structural strength perspective, traditional distillation columns, in actual service, must not only withstand their own weight but also cope with the pressure and temperature changes of the internal fluids, resulting in thermal stress, as well as the corrosive effects of strong acids, alkalis, and salts. Thermal stress is also a weak point in the mechanical properties of traditional distillation columns. During distillation, the fluid temperature inside the column often exhibits a significant gradient, from the high-temperature region at the bottom to the low-temperature region at the top. This temperature difference causes the column material to expand or contract to varying degrees. Because traditional distillation columns lack effective thermal compensation mechanisms in their structural design, the materials in different parts are mutually constrained by thermal expansion and contraction, thus generating thermal stress within the column. Prolonged exposure to this thermal stress environment will gradually lead to fatigue damage in the column material, reducing its mechanical properties and service life. These issues place higher demands on the selection of materials and the structural design of distillation columns.

[0004] High-purity SiC ceramics have excellent high-temperature mechanical properties and corrosion resistance, but due to their inherent brittleness, they are prone to brittle fracture, which seriously affects their application and promotion in the field of distillation columns. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a high-toughness and corrosion-resistant SiC-based composite distillation column structure and its design method, thereby overcoming the defects of poor toughness and easy fracture of existing ceramic distillation columns, ensuring that the distillation column has the advantages of high strength, high toughness, and corrosion resistance, while shortening the design cycle of ceramic-based composite distillation column structure and reducing design costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-toughness and corrosion-resistant SiC-based composite distillation column structure is composed of 4 to 6 layers of SiC-based composite material and an outermost SiC coating. The SiC-based composite material is composed of a C fiber preform and a SiC ceramic matrix covering the C fiber preform. The volume fraction of the single-layer C fiber preform gradually increases from the inner layer to the outer layer of the distillation column, and the weaving angle of each layer of C fiber preform is the same, which is the angle between the axis of a single SiC fiber and the axis of the distillation column.

[0008] Furthermore, the inner diameter of the distillation column is 200-250 mm, the length is 2000 mm, the wall thickness is 3-5 mm, and the SiC coating thickness is 0.1 mm. A distillation column with these dimensions can achieve efficient separation of raw materials, while maintaining adaptability and compatibility with the feed pipe, condenser, and discharge pipe, ensuring the operational stability of raw material separation.

[0009] Furthermore, the SiC-based composite material has 4 to 6 layers, which can ensure that the raw materials are not easily leaked and improve the safety of the materials during the separation process.

[0010] Furthermore, the volume fraction of the single-layer C fiber preform from the inner layer to the outer layer is 3%–5%, 7%–10%, 20%–30%, and 30%–40%, respectively, to ensure the high density of the SiC ceramic matrix inside the distillation column and improve the toughness of the distillation column, ensuring that it does not break suddenly; the weaving angle of the single-layer C fiber preform is 30°–60°, to ensure that the distillation column has high tensile strength.

[0011] This invention also provides a design method for a high-toughness and corrosion-resistant SiC-based composite distillation column structure, comprising the following steps:

[0012] a. Determine the number of braided layers of the composite distillation column, as well as the volume fraction, braiding angle, and braiding radius of each C-fiber preform: Based on the total wall thickness of the distillation column and the thickness of a single layer of the composite distillation column, determine the number of braided layers. Determine the diameter of each C-fiber preform from the inner diameter of the composite distillation column. Set the volume fraction of each C-fiber preform according to the increasing pattern from the inner layer to the outer layer. Determine the braiding angle of each C-fiber preform according to the braiding parameters set by the braiding machine.

[0013] b. Establishing a single-layer composite distillation column with different inner diameters: Based on the diameter of the C fiber preform determined in step a, establish multiple SiC ceramic matrices that completely cover the C fiber preforms, and make the C fiber preforms and SiC ceramic matrices form a composite to form a single-layer composite distillation column with different inner diameters.

[0014] c. Establishing a multilayer composite distillation column with SiC coating: After combining multiple single-layer composite distillation columns established in step b in order of increasing inner diameter, cover the surface of the outermost composite distillation column with a SiC coating to form a multilayer composite distillation column with SiC coating.

[0015] d. Calculate the tensile strength of the multilayer composite distillation column: Import the multilayer composite distillation column established in step c into the finite element calculation software, perform material definition, mesh generation, boundary condition setting, and calculation to obtain the stress-strain curve, and finally determine the tensile strength of the multilayer composite distillation column.

[0016] Furthermore, the single-layer composite distillation column with different inner diameters includes distillation columns with inner wall radii of 100–125 mm, 100.5–125.5 mm, 101 mm–126 mm, and 101.5–126.5 mm.

[0017] Furthermore, the material definition defines the SiC matrix and SiC coating as brittle materials, and the C fiber preform as a tough material, ensuring accurate calculation of the tensile strength and ultimate tensile strain of the designed distillation column and improving the reliability of the calculation results.

[0018] Furthermore, the boundary conditions are set on the upper and lower surfaces of the multilayer composite distillation column along the axial direction, with an increasing sequence starting at 0 mm, a step size of 0.001 to 0.004 mm, and an ending size of 0.2 mm to 0.3 mm. The smaller step size can improve the convergence stability during numerical calculation and ensure the accuracy of the calculation results.

[0019] Furthermore, the stress-strain curve is plotted with axial strain on the horizontal axis and axial stress on the vertical axis. The axial stress corresponding to the highest point of the curve is not less than 250 MPa, and the corresponding axial strain is not less than 0.125%.

[0020] By adopting the above technical solution, the advantages and beneficial effects of the present invention are as follows:

[0021] The high-toughness and corrosion-resistant SiC-based composite distillation column of this invention consists of 4 to 6 layers of SiC-based composite material and an outermost SiC coating layer. The volume fraction of C fiber preforms in the single-layer SiC-based composite material gradually increases from the inner layer to the outer layer of the distillation column. The axial tensile strength of the multilayer composite distillation column with this structure can reach 254.37 MPa, indicating that it has high strength. At the same time, the ultimate tensile strain of this distillation column is not less than 0.125%, which is 25% higher than that of high-purity SiC ceramics, indicating that the structure exhibits high toughness.

[0022] The stress-strain curve of a SiC-based composite distillation column with high toughness and corrosion resistance was calculated by finite element method. This not only obtained its tensile strength and ultimate tensile strain under axial tension, but also reduced the cost of distillation column design and testing, shortened the material design cycle, and promoted the development and application of ceramic-based composite distillation tubes.

[0023] In addition, the SiC-based composite distillation column of the present invention has a high degree of structural densification, which makes it difficult for corrosive media to penetrate into the material, thereby enhancing its corrosion resistance. At the same time, the SiC-based composite distillation column does not react chemically or dissolve with most strong acids and bases. This characteristic enables it to effectively prevent its internal structure from being corroded and damaged when in contact with corrosive media for a long time, thereby extending its service life. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the structural design of an embodiment of the present invention;

[0025] Figure 2 The multilayer composite distillation column with SiC coating designed in this embodiment of the invention has an inner wall radius of 100 mm, 100.8 mm, 101.6 mm, 102.4 mm and 0.1 mm SiC coating from the inside to the outside.

[0026] Figure 3 The figures below represent C-fiber preforms with different volume fractions designed according to embodiments of the present invention. The volume fractions of each layer of C-fiber preform from the inside out are 5%, 8%, 15%, and 30%.

[0027] Figure 4 The stress-strain curve is calculated for an embodiment of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] The high-toughness and corrosion-resistant SiC-based composite distillation column in this embodiment of the invention consists of four layers of SiC-based composite material and an outermost SiC coating layer. Its design method is described in [link to design details]. Figure 1 .

[0030] Example 1

[0031] In this embodiment, as Figure 2 As shown, the inner wall radii of each SiC-based composite distillation column, from smallest to largest, are 100 mm, 100.8 mm, 101.6 mm, and 102.4 mm, respectively. The column length is 2000 mm, and the wall thickness is 3.3 mm. Figure 3As shown, the volume fraction of C fiber preforms in the single-layer SiC matrix composite material is 5%, 8%, 15%, and 30% from the inside to the outside, and the weaving angle of the C fiber preforms is 45°.

[0032] The specific design method is as follows:

[0033] Step 1: Determine the number of braided layers of the composite distillation column, as well as the volume fraction, braiding angle, and braiding radius of each C-fiber preform. Based on the total wall thickness of the distillation column (3.3 mm) and the thickness of a single composite distillation column (0.8 mm), the number of braided layers is determined to be 4. The radii of each C-fiber preform are determined to be 100.2 mm, 101 mm, 101.8 mm, and 102.6 mm, respectively, based on the inner diameter of the composite distillation column (200 mm). The volume fractions of each C-fiber preform are set according to the increasing pattern from the inner to the outer layers, which are 5%, 8%, 15%, and 30%, respectively. The braiding angle of each C-fiber preform is determined to be 45° based on the braiding parameters set on the braiding machine.

[0034] Step 2, establish single-layer composite distillation columns with different inner diameters: Based on the radius of the C fiber preform determined in Step 1, establish multiple SiC ceramic matrices that completely cover the C fiber preforms, and combine the C fiber preforms with the SiC ceramic matrices to form single-layer composite distillation columns with different inner diameters, with inner wall radii of 100 mm, 100.8 mm, 101.6 mm, and 102.4 mm, respectively.

[0035] Step 3, establish a multilayer composite distillation column with SiC coating: After combining multiple single-layer composite distillation columns established in Step 2 in order of increasing inner diameter, cover the surface of the outermost composite distillation column with a SiC coating of 0.1 mm thickness to form a multilayer composite distillation column with SiC coating, which is 2000 mm long and 3.3 mm thick.

[0036] Step 4: Calculate the tensile strength of the multilayer composite distillation column: Import the multilayer composite distillation column established in Step 3 into the finite element method (FEM) software. Define the SiC ceramic matrix and SiC coating as brittle materials, and the C fiber preform as a tough material. Mesh the column as a tetrahedral mesh. Set boundary conditions on the upper and lower surfaces of the multilayer composite distillation column along the axial direction, starting at 0 mm, with a step size of 0.001–0.004 mm, and ending at 0.2 mm–0.3 mm. Solve using the Newton-Raphson iteration method to obtain the stress-strain curve. The final tensile strength of the multilayer composite distillation column is determined to be 254.37 MPa, corresponding to an axial strain of 0.14%. Figure 4 As shown, the stress-strain curve of the 4-layer SiC-based distillation column calculated in this embodiment is shown. The highest point of the curve is 254.37 MPa, and the corresponding axial strain is 0.14%.

[0037] The multilayer SiC-based composite distillation column designed in this invention has the characteristics of corrosion resistance, high strength, and high toughness, which makes up for the lack of toughness of high-purity SiC ceramic distillation columns and realizes the performance optimization of ceramic-based distillation columns.

[0038] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A high-toughness corrosion-resistant SiC-based composite distillation column structure, characterized in that, The SiC-based composite material is composed of a C fiber preform and a SiC ceramic matrix covering the C fiber preform, the volume fraction of the C fiber preform gradually increases from the inner layer to the outer layer of the distillation column, and the braiding angle of each layer of C fiber preform is the same, and the braiding angle is the included angle between the axis of a single SiC fiber and the axis of the distillation column.

2. A high toughness corrosion resistant SiC based composite distillation column structure according to claim 1, characterized in that, The inner diameter of the distillation column is 200-250 mm, the length is 2000 mm, the wall thickness is 3-5 mm, and the SiC coating thickness is 0.1 mm.

3. The high-toughness corrosion-resistant SiC-based composite distillation column structure according to claim 1, characterized in that, The SiC-based composite material is 4-6 layers.

4. The high toughness corrosion resistant SiC-based composite distillation column structure according to claim 1, wherein, The volume fraction of the C fiber preform in the SiC-based composite material is 3-5%, 7-10%, 20-30%, and 30-40% from the inner layer to the outer layer, and the braiding angle of the C fiber preform is 30-60°.

5. The design method of a high-toughness corrosion-resistant SiC-based composite distillation column structure according to any one of claims 1 to 4, characterized in that, The steps include: a. Determine the number of braiding layers of the composite distillation column, and the volume fraction, braiding angle and braiding radius of each layer of C fiber preform: according to the total wall thickness of the distillation column and the thickness of the single layer composite distillation column, determine the number of braiding layers, determine the diameter of each layer of C fiber preform according to the inner diameter of the composite distillation column, set the volume fraction of each layer of C fiber preform according to the increasing rule from the inner layer to the outer layer, and determine the braiding angle of each layer of C fiber preform according to the braiding parameters set by the braiding machine; b. Establish a single layer composite distillation column with different inner diameters: based on the diameter of the C fiber preform determined in step a, establish multiple SiC ceramic matrices completely covering the C fiber preform, and form a combination of C fiber preform and SiC ceramic matrix, to form a single layer composite distillation column with different inner diameters; c. Establish a multi-layer composite distillation column with SiC coating: after the multiple single layer composite distillation columns established in step b are combined in order from small to large inner diameter, a layer of SiC coating is covered on the surface of the outermost composite distillation column to form a multi-layer composite distillation column with SiC coating; d. Calculate the tensile strength of the multi-layer composite distillation column: introduce the multi-layer composite distillation column established in step c into the finite element calculation software, respectively perform material definition, mesh division, boundary condition setting, calculation and solution, obtain the stress-strain curve, and finally determine the tensile strength of the multi-layer composite distillation column.

6. The method of designing a high-toughness corrosion-resistant SiC-based composite distillation column structure according to claim 5, characterized in that, The single layer composite distillation column with different inner diameters in step b includes a distillation column with an inner wall radius of 100-125 mm, 100.5-125.5 mm, 101 mm-126 mm, and 101.5-126.5 mm.

7. The method of designing a high-toughness corrosion-resistant SiC-based composite distillation column structure according to claim 5, characterized in that, The material definition in step d is to define the SiC ceramic matrix and SiC coating as brittle materials, and the C fiber preform as a ductile material.

8. The method of designing a high-toughness corrosion-resistant SiC-based composite distillation column structure according to claim 5, characterized in that, The boundary condition in step d is to set an increasing sequence along the axis direction on the upper and lower surfaces of the multi-layer composite distillation column, with 0 mm as the starting value, 0.001-0.004 mm as the step, and 0.2-0.3 mm as the termination.

9. The method of designing a high-toughness corrosion-resistant SiC-based composite distillation column structure according to claim 5, characterized in that, The stress-strain curve in step d is with the axial strain as the horizontal axis and the axial stress as the vertical axis, the axial stress corresponding to the highest point of the curve is not less than 250 MPa, and the corresponding axial strain is not less than 0.125%. The stress-strain curve in step d is with the axial strain as the horizontal axis and the axial stress as the vertical axis, the axial stress corresponding to the highest point of the curve is not less than 250 MPa, and the corresponding axial strain is not less than 0.125%. The stress-strain curve in step d is with the axial strain as the horizontal axis and the axial stress as the vertical axis, the axial

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