High-toughness corrosion-resistant SiC-based composite distillation column structure and design method thereof

Abstract

The invention discloses a high-toughness corrosion-resistant SiC-based composite distillation column structure and a design method thereof.The composite distillation column structure is composed of multiple layers of SiC-based composite materials and a SiC coating on the outermost layer, and the SiC-based composite materials are composed of C fiber preforms and SiC ceramic matrixes wrapping the C fiber preforms; the volume fraction of the single-layer C fiber preform is gradually increased from the inner layer of the distillation column to the outer layer of the distillation column; the design method comprises the following steps: a, determining the weaving layer number of the composite distillation column and the fiber volume fraction and the fiber weaving angle of each layer; b, establishing single-layer composite distillation columns with different inner diameters; c, establishing a multi-layer composite distillation column with a SiC coating; and d, calculating the tensile strength of the multi-layer composite distillation column. The multilayer SiC-based composite distillation column designed by the invention has the characteristics of corrosion resistance, high strength and high toughness, overcomes the defect of insufficient toughness of a high-purity SiC ceramic distillation column, and realizes performance optimization of the ceramic-based distillation column.

Description

Technical Field

[0001] The invention relates to the technical field of distillation columns in separation, purification and synthesis in the chemical industry, and specifically provides a high-toughness, corrosion-resistant SiC-based composite distillation column structure and a design method thereof. Background Art

[0002] In many key areas of modern industry, such as chemical, petroleum, pharmaceutical and energy, distillation column is one of the core equipment. The quality of its mechanical properties has a significant impact on the safety, stability and durability of the entire production system. However, there are many problems in the mechanical properties of traditional distillation columns that need to be solved.

[0003] From the perspective of structural strength, when the traditional distillation column is in actual service, it not only has to bear its own gravity load, but also has to deal with the pressure of the internal fluid, the thermal stress caused by temperature changes, and the corrosion of strong acids, strong alkalis, and strong salts. The thermal stress problem is also a weak link in the mechanical properties of traditional distillation columns. During the distillation process, the temperature of the fluid in the column often has a large gradient change, from the high temperature area at the bottom to the low temperature area at the top. This temperature difference will cause the column material to expand or contract to varying degrees. Since the traditional distillation column lacks an effective thermal compensation mechanism in the structural design, the materials in different parts are mutually constrained due to thermal expansion and contraction, thereby generating thermal stress in the column. Under this thermal stress environment for a long time, the column material will gradually suffer fatigue damage, reducing its mechanical properties and service life. These problems put forward higher requirements for the material selection and structural design of the distillation column.

[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 distillation column field. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a high-toughness and corrosion-resistant SiC-based composite distillation column structure and a design method thereof, aiming to make up for the defects of poor toughness and easy fracture of existing ceramic distillation columns, ensure that the distillation column has the advantages of high strength, high toughness and corrosion resistance, and at the same time shorten the design cycle of the ceramic-based composite distillation column structure and reduce the design cost.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A high-toughness, corrosion-resistant SiC-based composite distillation column structure is composed of 4 to 6 layers of SiC-based composite materials and an outermost layer of SiC coating, wherein the SiC-based composite material is composed of a C fiber preform and a SiC ceramic matrix coating the C fiber preform, the volume fraction of a single-layer C fiber preform gradually increases from an inner layer to an outer layer of the distillation column, and the braiding angle of each layer of the 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 of this size 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 fractions of the single-layer C fiber preform are 3% to 5%, 7% to 10%, 20% to 30%, and 30% to 40% from the inner layer to the outer layer, respectively, to ensure the high density of the SiC ceramic matrix inside the distillation column, while improving the toughness of the distillation column to ensure that it does not break suddenly; the weaving angle of the single-layer C fiber preform is 30° to 60°, to ensure that the distillation column has a high tensile strength.

[0011] The present invention also provides a design method for a high-toughness, 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 and the volume fraction, braiding angle, and braiding radius of each layer of the C fiber preform: Determine the number of braided layers based on the total wall thickness of the distillation column and the thickness of the single-layer composite distillation column, determine the diameter of each layer of the C fiber preform based on the inner diameter of the composite distillation column, set the volume fraction of each layer of the C fiber preform according to the rule of increasing from the inner layer to the outer layer, and determine the braiding angle of each layer of the C fiber preform based on 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, establishing a plurality of SiC ceramic matrices completely covering the C fiber preforms, and forming a consortium of the C fiber preform and the SiC ceramic matrix to form a single-layer composite distillation column with different inner diameters;

[0014] c. Establishing a multilayer composite distillation column having a SiC coating: After the plurality of single-layer composite distillation columns established in step b are connected 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 multilayer composite distillation column having a 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 division, boundary condition setting, calculation and solution, 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 is to define the SiC matrix and the SiC coating as brittle materials and the C fiber preform as tough material, so as to ensure accurate calculation of the tensile strength and ultimate tensile strain of the designed distillation column and improve the reliability of the calculation results.

[0018] Furthermore, the boundary conditions are set on the upper and lower surfaces of the multi-layer composite distillation column along the axial direction, with 0 mm as the starting value, 0.001 to 0.004 mm as the step length, and 0.2 mm to 0.3 mm as the termination increasing series. A smaller step length can improve the convergence stability during numerical calculation and ensure the accuracy of the calculation results.

[0019] Furthermore, the stress-strain curve has 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%.

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

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

[0022] The stress-strain curve of the SiC-based composite distillation column with high toughness and corrosion resistance was calculated using the finite element method. Not only was its tensile strength and ultimate tensile strain under axial tension obtained, but the cost of distillation column design and testing was also reduced, and the material design cycle was shortened, which 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 invade the interior of the material, thereby enhancing its corrosion resistance. At the same time, the SiC-based composite distillation column does not chemically react with or be dissolved by most strong acids and alkalis. This feature can effectively prevent its internal structure from being corroded and damaged when it is in long-term contact with corrosive media, thereby extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of the structure design of an embodiment of the present invention;

[0025] Figure 2 The multi-layer composite distillation column with SiC coating designed in the embodiment of the present invention, the inner wall radius of each layer of SiC-based composite distillation column is 100mm, 100.8mm, 101.6mm, 102.4mm and 0.1mm SiC coating from the inside to the outside;

[0026] Figure 3 , respectively, C fiber preforms with different volume fractions are designed according to the embodiments of the present invention, and the volume fractions of each layer of C fiber preforms are 5%, 8%, 15%, and 30% from the inside to the outside;

[0027] Figure 4 This is a stress-strain curve diagram calculated for an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0029] The high toughness and corrosion resistant SiC-based composite distillation column in the embodiment of the present invention is composed of 4 layers of SiC-based composite materials and an outermost layer of SiC coating. Figure 1 .

[0030] Example 1

[0031] In this embodiment, Figure 2 As shown, the inner wall radius of each layer of the SiC-based composite distillation column is 100 mm, 100.8 mm, 101.6 mm, and 102.4 mm from small to large, the length of the distillation column is 2000 mm, and the wall thickness is 3.3 mm. Figure 3As shown, the volume fractions of the C fiber preform in the single-layer SiC-based composite material are 5%, 8%, 15%, and 30% from the inside to the outside, and the braiding angle of the C fiber preform is 45°.

[0032] The specific design method is:

[0033] Step 1, determine the number of braided layers of the composite distillation column and the volume fraction, braiding angle, and braiding radius of each layer of the C fiber preform: based on the total wall thickness of the distillation column of 3.3 mm and the thickness of the single-layer composite distillation column of 0.8 mm, determine the number of braided layers to be 4 layers, and determine the radius of each layer of the C fiber preform 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 of 200 mm. Set the volume fraction of each layer of the C fiber preform according to the rule of increasing from the inner layer to the outer layer, which are 5%, 8%, 15%, and 30% respectively. Determine the braiding angle of each layer of the C fiber preform to be 45° according to the braiding parameters set by the braiding machine;

[0034] Step 2, establishing a single-layer composite distillation column with different inner diameters: based on the radius of the C fiber preform determined in step 1, establishing a plurality of SiC ceramic matrices that completely cover the C fiber preform, and making the C fiber preform and the SiC ceramic matrix form a union to form a single-layer composite distillation column with different inner diameters, wherein the inner wall radii are 100 mm, 100.8 mm, 101.6 mm, and 102.4 mm, respectively;

[0035] Step 3, establishing a multilayer composite distillation column with a SiC coating: after the multiple single-layer composite distillation columns established in step 2 are connected and assembled in order of inner diameter from small to large, a layer of SiC coating with a thickness of 0.1 mm is covered on the surface of the outermost composite distillation column to form a multilayer composite distillation column with a SiC coating, which has a length of 2000 mm and a wall thickness of 3.3 mm;

[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 calculation software, define the SiC ceramic matrix and the SiC coating as brittle materials, define the C fiber preform as a tough material, divide the grid into tetrahedral grids, set the upper and lower surfaces of the multilayer composite distillation column along the axial direction, with 0mm as the starting value, 0.001-0.004mm as the step length, and 0.2mm-0.3mm as the termination increment series as the boundary condition, calculate and solve by Newton iteration method, obtain the stress-strain curve, and finally determine that the tensile strength of the multilayer composite distillation column is 254.37MPa, and the corresponding axial strain is 0.14%, such as Figure 4 As shown, it is the stress-strain curve of the 4-layer SiC-based distillation column calculated in this embodiment. The highest point of the curve is 254.37 MPa, and the corresponding axial strain at this time is 0.14%.

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

[0038] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A high-toughness, corrosion-resistant SiC-based composite distillation column structure, characterized in that: The invention is composed of a multi-layer SiC-based composite material and an outermost layer of SiC coating, wherein the SiC-based composite material is composed of a C fiber preform and a SiC ceramic matrix coating 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 braiding angle of each layer of the 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.

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

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

5. The method for designing a high-toughness, corrosion-resistant SiC-based composite distillation column structure according to any one of claims 1 to 4, characterized in that: The following steps are involved: a. Determine the number of braided layers of the composite distillation column and the volume fraction, braiding angle, and braiding radius of each layer of the C fiber preform: Determine the number of braided layers based on the total wall thickness of the distillation column and the thickness of the single-layer composite distillation column, determine the diameter of each layer of the C fiber preform based on the inner diameter of the composite distillation column, set the volume fraction of each layer of the C fiber preform according to the rule of increasing from the inner layer to the outer layer, and determine the braiding angle of each layer of the C fiber preform based on the braiding parameters set by the braiding machine; 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, establishing a plurality of SiC ceramic matrices completely covering the C fiber preforms, and forming a consortium of the C fiber preform and the SiC ceramic matrix to form a single-layer composite distillation column with different inner diameters; c. Establishing a multilayer composite distillation column having a SiC coating: After the plurality of single-layer composite distillation columns established in step b are connected 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 multilayer composite distillation column having a SiC coating; 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 division, boundary condition setting, calculation and solution, obtain the stress-strain curve, and finally determine the tensile strength of the multilayer composite distillation column.

6. The design method of a high-toughness, corrosion-resistant SiC-based composite distillation column structure according to claim 5, characterized in that: The single-layer composite distillation columns with different inner diameters described in step b include 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.

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

8. The design method of a high-toughness, corrosion-resistant SiC-based composite distillation column structure according to claim 5, characterized in that: The boundary conditions described in step d are set on the upper and lower surfaces of the multilayer composite distillation column along the axial direction, with 0 mm as the starting value, 0.001 to 0.004 mm as the step length, and 0.2 mm to 0.3 mm as the ending incremental series.

9. The design method of a high-toughness, corrosion-resistant SiC-based composite distillation column structure according to claim 5, characterized in that: The stress-strain curve described in step d has 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%.

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