A ceramic nanofiber tube shell and a preparation method and application thereof

Abstract

The application relates to the technical field of pipeline heat preservation, and discloses a ceramic nanofiber pipe shell as well as a preparation method and application thereof. The method comprises the following steps: (1) pretreating waste aluminum silicate fiber to obtain fiber raw materials with an average length of 5-50 mm; (2) mixing the fiber raw materials, an additive and a binding agent to obtain a first mixed material, and performing forming treatment on the first mixed material to obtain a precursor; and (3) performing first drying treatment on the precursor. The ceramic nanofiber pipe shell prepared by the method can effectively improve the comprehensive utilization rate of the waste aluminum silicate cotton, and can also obtain a ceramic nanofiber pipe shell product with excellent performance.

Description

Technical Field

[0001] This invention relates to the field of pipeline insulation technology, specifically to a ceramic nanofiber pipe shell, its preparation method, and its application. Background Technology

[0002] Currently, my country treats aluminum silicate cotton products in much the same way as general industrial solid waste. Due to cost pressures related to time, manpower, and capital, most enterprises primarily handle waste aluminum silicate products through open-air dumping, natural ditch filling, and pit filling. These methods pose real and potential dangers to soil, groundwater, and the atmosphere.

[0003] Waste insulation materials from general industrial enterprises are treated as useless solid waste, either discarded or landfilled, which not only poses a serious threat to the ecological environment, but also leads to the waste of a large amount of valuable resources.

[0004] Currently, research on the recycling of waste aluminum silicate cotton products is still in the experimental stage. Only a small portion is used as an auxiliary raw material for downgrading. For example, some companies have used waste aluminum silicate cotton products to produce composite thermal insulation materials for building exterior walls, but their recycling rate is low and the cost is high, making it difficult to promote.

[0005] Ceramic nanofiber cotton is a new type of lightweight nanoporous material. Its unique three-dimensional and nanoscale pore structure can effectively block heat conduction and heat convection, and at the same time, it can effectively reduce infrared radiation heat transfer.

[0006] Ceramic nanofiber blankets use a variety of fibers, such as glass fiber and ceramic fiber, as the framework. The ceramic materials are prepared into nanomaterials using colloidal methods and supercritical strengthening processes. More than 98% of the ceramic powder has a particle size of less than 40nm (the self-trajectory of air molecule clusters is about 70nm), forming a vacuum structure. This enables the realization of vacuum insulation structures in the field of industrial engineering, reducing the heat loss of the surface of the insulated body by more than 50%.

[0007] Due to its excellent thermal insulation, overall waterproof performance, good mechanical properties, and long service life without settling or deformation, ceramic nanofiber blankets are now widely used in the petrochemical and refining industries. While the widespread application of ceramic nanofiber blankets has saved users a significant amount of energy, related problems are also emerging, restricting the effectiveness of the new material and affecting the economic benefits for users.

[0008] Therefore, it is of great significance to find out how to use waste aluminosilicate cotton products to prepare ceramic nanofiber tube shells that meet performance requirements. Summary of the Invention

[0009] The purpose of this invention is to provide a method for preparing ceramic nanofiber tube shells using waste aluminosilicate cotton, so as to solve the problem of solid waste pollution caused by the low utilization rate of waste aluminosilicate cotton.

[0010] To achieve the above objectives, a first aspect of the present invention provides a method for preparing ceramic nanofiber tube shells, the method comprising:

[0011] (1) The waste aluminum silicate fiber is pretreated to obtain fiber raw material with an average length of 5-50mm; the content of Fe2O3 in the waste aluminum silicate fiber is ≤5wt%, the content of Al2O3 is 35-45wt%, and the content of SiO2 is 45-55wt%.

[0012] (2) The fiber raw material, additives and binder are contacted and mixed to obtain a first mixture, and the first mixture is molded to obtain a precursor; the molding conditions are controlled so that the moisture content of the precursor is ≤40wt%.

[0013] The additive is selected from at least one of sodium silicate, silica sol, and aluminum sol.

[0014] The binder is prepared by using an organic surfactant and an inorganic dispersant in a mass ratio of 1:0.3-0.5; the organic surfactant is an organic surfactant containing at least two groups selected from sulfonic acid group, sulfate ester group, amide group, hydroxyl group, ammonium group, and oxyethylene group; and the inorganic dispersant is selected from at least one of sodium tripolyphosphate, sodium hexametaphosphate, calcium lignosulfonate, and sodium lignosulfonate.

[0015] (3) The precursor is subjected to a first drying treatment.

[0016] A second aspect of the present invention provides a ceramic nanofiber tube shell prepared by the method described in the first aspect.

[0017] The third aspect of this invention provides the application of the ceramic nanofiber tube shell described in the second aspect in thermal insulation materials.

[0018] The method provided by this invention for preparing ceramic nanofiber tube shells can not only effectively improve the comprehensive utilization rate of waste aluminosilicate cotton, but also obtain ceramic nanofiber tube shell products with excellent performance. Attached Figure Description

[0019] Figure 1 These are X-ray diffraction patterns of brand-new aluminosilicate fibers and waste aluminosilicate fibers 1 provided by this invention;

[0020] Figure 2 These are scanning electron microscope images of brand-new aluminum silicate fibers and waste aluminum silicate fibers 1 provided by this invention. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] In this invention, unless otherwise stated, room temperature or normal temperature refers to 25±2℃.

[0023] In this invention, unless otherwise stated, all pressures are gauge pressures.

[0024] As previously described, a first aspect of the present invention provides a method for preparing ceramic nanofiber tube shells, the method comprising:

[0025] (1) The waste aluminum silicate fiber is pretreated to obtain fiber raw material with an average length of 5-50mm; the content of Fe2O3 in the waste aluminum silicate fiber is ≤5wt%, the content of Al2O3 is 35-45wt%, and the content of SiO2 is 45-55wt%.

[0026] (2) The fiber raw material, additives and binder are contacted and mixed to obtain a first mixture, and the first mixture is molded to obtain a precursor; the molding conditions are controlled so that the moisture content of the precursor is ≤40wt%.

[0027] The additive is selected from at least one of sodium silicate, silica sol, and aluminum sol.

[0028] The binder is prepared by using an organic surfactant and an inorganic dispersant in a mass ratio of 1:0.3-0.5; the organic surfactant is an organic surfactant containing at least two groups selected from sulfonic acid group, sulfate ester group, amide group, hydroxyl group, ammonium group, and oxyethylene group; and the inorganic dispersant is selected from at least one of sodium tripolyphosphate, sodium hexametaphosphate, calcium lignosulfonate, and sodium lignosulfonate.

[0029] (3) The precursor is subjected to a first drying treatment.

[0030] Preferably, in step (1), the pretreatment includes sequentially performing a first cleaning, a first soaking, and a second drying treatment on the waste aluminum silicate fiber.

[0031] Preferably, in step (1), the solvent used for the first cleaning is water, and the first cleaning is performed 1-5 times.

[0032] The present invention does not have any special requirements on the amount of solvent used in the first cleaning process, as long as it meets the requirements of the present invention.

[0033] Preferably, in step (1), the conditions for the first soaking include at least a time of 20-30 hours.

[0034] Preferably, in step (1), the conditions for the second drying process include at least: a temperature of 100-150°C and a time of 20-30 hours.

[0035] Preferably, in step (1), the method further includes: dissolving the waste aluminum silicate fiber after the first cleaning in the presence of ethanol.

[0036] Preferably, in step (1), the dissolution conditions include at least: a stirring speed of 30-100 rpm, a temperature of 20-40°C, and a time of 30-60 min.

[0037] Preferably, in step (1), the pretreatment further includes: crushing the dissolved waste aluminum silicate fiber to obtain fiber fragments with an average length of 5-50 mm.

[0038] The present invention does not have any particular requirements for the specific operation method of the crushing process, and methods known in the art can be used.

[0039] Preferably, in step (2), the conditions for contact mixing include at least: a stirring speed of 30-100 rpm, a temperature of 18-30°C, and a time of 30-60 min.

[0040] Preferably, in step (2), the amount of the additive is 0.03-0.09g relative to 1g of the fiber raw material, and the amount of the binder is 0.1-0.8g.

[0041] More preferably, in step (2), the amount of the additive is 0.033-0.084 g relative to 1 g of the fiber raw material, and the amount of the binder is 0.11-0.67 g. The inventors have found that, by adopting this preferred embodiment, ceramic nanofiber tube shells with superior pressure resistance can be obtained.

[0042] According to a particularly preferred embodiment, in step (2), the binder is prepared by a method comprising the following steps:

[0043] S1. Dissolve ethanolamine and glucose in ethanol to obtain material I, and then react material I with catalyst I to obtain material II;

[0044] S2. In the presence of propylene glycol and catalyst II, the material II and component A are subjected to contact reaction II to obtain an organic surfactant; wherein, component A is a fatty acid methyl ester or sodium fatty acid methyl ester sulfonate.

[0045] S3. In the presence of water, the organic surfactant is mixed with hydrophobic nano-silica to obtain material III, and material III is mixed with an inorganic dispersant to obtain material II.

[0046] The inventors discovered that by adopting the specific implementation method under this preferred condition, a binder with superior performance can be obtained. When the binder obtained under this preferred condition is applied to the preparation of ceramic nanofiber tube shells, ceramic nanofiber tube shells with lower thermal conductivity can be prepared.

[0047] Preferably, in step S1, the molar ratio of ethanolamine to glucose is 1-6:1.

[0048] Preferably, in step S1, the catalyst I is a nickel boride catalyst.

[0049] Preferably, in step S1, the conditions for the contact reaction I include at least: a temperature of 40-60°C and a time of 6-10 hours.

[0050] Preferably, in step S2, the catalyst II is an aqueous solution of sodium hydroxide with a concentration of 20wt% to 30wt%.

[0051] Preferably, in step S2, the molar ratio of material II to component A is 1-6:1.

[0052] Preferably, in step S2, the contact reaction II is carried out under vacuum conditions, and the conditions of the contact reaction II include at least: a vacuum degree of 0.09-0.1 MPa, a temperature of 120-150°C, and a time of 2-5 h.

[0053] Preferably, in step S2, the mass ratio of the water, the hydrophobic nano-silica, and the organic surfactant is 6-10:1-3:1.

[0054] Preferably, in step S3, the conditions for mixing I include at least: a stirring speed of 50-80 rpm, a temperature of 20-40°C, and a time of 1-10 min.

[0055] Preferably, in step S3, the mixing II is performed under ultrasonic conditions, and the conditions of the mixing II include at least: an ultrasonic frequency of 20-100 kHz, a temperature of 10-30 °C, and a time of 12-30 min.

[0056] Preferably, in step S3, the average particle size of the hydrophobic nano-silica is 30-80 nm.

[0057] Preferably, in step (2), the conditions of the molding process are controlled such that the water content of the precursor is 10-40 wt%.

[0058] Preferably, in step (2), the molding process conditions include at least the following: temperature of 18-30°C, pressure of 10-30 MPa, and time of 10-30 min.

[0059] Preferably, in step (3), the conditions for the first drying process include at least: a temperature of 110-350°C and a time of 24-30h.

[0060] As previously stated, a second aspect of the present invention provides a ceramic nanofiber tube shell prepared by the method described in the first aspect.

[0061] Preferably, the bulk density of the ceramic nanofiber tube shell is ≤200 kg / m³. 3 .

[0062] Preferably, the pressure resistance of the ceramic nanofiber tube shell is ≥200 kPa.

[0063] Preferably, the thermal conductivity of the ceramic nanofiber tube shell at a hot surface temperature of 600°C is ≤0.065w / mk.

[0064] As previously stated, the third aspect of the present invention provides the application of the ceramic nanofiber tube shell described in the second aspect in thermal insulation materials.

[0065] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used are commercially available products.

[0066] Ethanolamine: Purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0067] Glucose: Purchased from Aladdin Reagent (Shanghai) Co., Ltd.;

[0068] Catalyst I: Nickel boride, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0069] Component A: Sodium fatty acid methyl ester sulfonate, purchased from Aladdin Reagent (Shanghai) Co., Ltd.;

[0070] Hydrophobic nano-silica: average particle size 30nm, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0071] Inorganic dispersant: Sodium tripolyphosphate, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0072] Inorganic dispersant: Sodium hexametaphosphate, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0073] Waste aluminum silicate fiber 1: In the waste aluminum silicate fiber, the content of Fe2O3 is 0.37wt%, the content of Al2O3 is 36.02wt%, and the content of SiO2 is 46.2wt%.

[0074] Waste aluminum silicate fiber 2: In the waste aluminum silicate fiber, the content of Fe2O3 is 5wt%, the content of Al2O3 is 39.14wt%, and the content of SiO2 is 46.95wt%.

[0075] Additive: Sodium silicate, analytical grade reagent;

[0076] Additive: Silica sol, purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd.;

[0077] Additive: Aluminum sol, purchased from Zibo Jinqi Chemical Technology Co., Ltd.

[0078] Preparation Example 1

[0079] This preparation example is used to prepare binder A1.

[0080] At room temperature, 3 mol of ethanolamine and 1 mol of glucose were dissolved in 240 mL of ethanol to obtain material I. Material I was then reacted with catalyst I in a contact reaction I (temperature 50 °C, time 8 h) to obtain material II. Then, 1 mol of material II and 1 mol of sodium fatty acid methyl ester sulfonate were dissolved in 20 wt% propylene glycol, and 1100 mL of catalyst II (20 wt% sodium hydroxide aqueous solution) was added. The mixture was reacted under vacuum (vacuum degree 0.095 MPa) at 150 °C for 5 h to obtain an organic surfactant.

[0081] At room temperature, 4 kg of hydrophobic nano-silica, 16 kg of water, and 2 kg of organic surfactant were mixed and stirred at 60 rpm for 5 min. Then, 0.6 kg of sodium tripolyphosphate was added, and the mixture was ultrasonically vibrated at 20 °C (ultrasonic frequency of 50 kHz) for 20 min to obtain binder A1.

[0082] Preparation Example 2

[0083] This preparation example is used to prepare binder A2.

[0084] At room temperature, 3 mol of ethanolamine and 1 mol of glucose were dissolved in 320 mL of ethanol to obtain material I. Material I was then subjected to contact reaction I with catalyst I (temperature 60 °C, time 7 h) to obtain material II. Then, 1 mol of material II and 1 mol of fatty acid methyl ester sulfonic acid were dissolved in 20 wt% propylene glycol, and 1200 mL of catalyst II (25 wt% sodium hydroxide aqueous solution) was added. The mixture was reacted under vacuum (vacuum degree 0.095 MPa) at 150 °C for 5 h to obtain an organic surfactant.

[0085] At room temperature, 10 kg of hydrophobic nano-silica, 40 kg of water, and 5 kg of organic surfactant were mixed and stirred at 60 rpm for 5 min. Then, 2 kg of sodium hexametaphosphate was added, and the mixture was ultrasonically vibrated at 24 °C (ultrasonic frequency of 50 kHz) for 20 min to obtain binder A2.

[0086] Preparation Example 3

[0087] This preparation example is used to prepare binder A3.

[0088] At room temperature, 3 mol of ethanolamine and 1 mol of glucose were dissolved in 320 mL of ethanol to obtain material I. Material I was then subjected to contact reaction I with catalyst I (temperature 40 °C, time 10 h) to obtain material II. Then, 1 mol of material II and 1 mol of fatty acid methyl ester sulfonic acid were dissolved in 20 wt% propylene glycol, and 1400 mL of catalyst II (30 wt% sodium hydroxide solution) was added. The mixture was reacted under vacuum (0.1 MPa) at 150 °C for 5 h to obtain an organic surfactant.

[0089] At room temperature, 20 kg of hydrophobic nano-silica, 80 kg of water, and 10 kg of organic surfactant were mixed and stirred at 80 rpm for 5 min. Then, 5 kg of sodium hexametaphosphate was added, and the mixture was ultrasonically vibrated at 22°C (ultrasonic frequency of 100 kHz) for 30 min to obtain binder A3.

[0090] Example 1

[0091] This embodiment provides a method for preparing ceramic nanofiber tube shells, the method comprising:

[0092] (1) At room temperature, 22 kg of waste aluminum silicate fiber 1 was washed three times with 300 L of water. During the washing process, 120 L of ethanol was added and stirred at 30 rpm for 40 min to dissolve. Then the washed waste aluminum silicate fiber 1 was crushed and soaked for 24 h. The soaked fiber fragments were dried at 110 ℃ for 24 h to obtain fiber raw material with an average length of 10 mm.

[0093] (2) At room temperature, 18 kg of the fiber raw material prepared above, 0.6 kg of sodium silicate and 2 kg of binder A1 were stirred at 60 rpm for 30 min to obtain the first mixture. The first mixture was placed in a tube shell forming mold with a volume of 50 L and the mold was placed in a small screw press and intermittently hammered at 20 MPa for 10 min. The formed mixture was filtered by a small disc vacuum filter to obtain a precursor with a water content of 32 wt%.

[0094] (3) The precursor prepared above was placed in an oven at 110°C for a first drying treatment for 24 hours to obtain ceramic nanofiber tube shell S1.

[0095] Example 2

[0096] This embodiment provides a method for preparing ceramic nanofiber tube shells, the method comprising:

[0097] (1) At room temperature, 30 kg of waste aluminum silicate fiber 1 was washed three times with 500 L of water. During the washing process, 200 L of ethanol was added and stirred at 50 rpm for 40 min to dissolve. Then the washed waste aluminum silicate fiber 1 was crushed and soaked for 24 h. The soaked fiber fragments were dried at 110 ℃ for 24 h to obtain fiber raw material with an average length of 20 mm.

[0098] (2) At room temperature, 25 kg of the fiber raw material prepared above, 1.2 kg of silica sol and 5 kg of binder A2 are stirred at 70 rpm for 40 min to obtain the first mixture. The first mixture is placed in a tube shell forming mold with a volume of 50 L. The mold is then placed in a small screw press and intermittently hammered at 20 MPa for 20 min. The formed mixture is filtered by a small disc vacuum filter to obtain a precursor with a water content of 35 wt%.

[0099] (3) The precursor prepared above was placed in an oven at 200°C for a first drying treatment for 26 hours to obtain ceramic nanofiber tube shell S2.

[0100] Example 3

[0101] This embodiment provides a method for preparing ceramic nanofiber tube shells, the method comprising:

[0102] (1) At room temperature, 36 kg of waste aluminum silicate fiber 1 was washed three times with 600 L of water. During the washing process, 240 L of ethanol was added and stirred at 70 rpm for 40 min to dissolve. Then the washed waste aluminum silicate fiber 1 was crushed and soaked for 24 h. The soaked fiber fragments were dried at 110 ℃ for 24 h to obtain fiber raw material with an average length of 20 mm.

[0103] (2) At room temperature, 30 kg of the fiber raw material prepared above, 2.5 kg of aluminum sol and 20 kg of binder A3 are stirred at 100 rpm for 40 min to obtain the first mixture. The first mixture is placed in a tube shell forming mold with a volume of 50 L. The mold is then placed in a small screw press and intermittently hammered at 20 MPa for 20 min. The formed mixture is filtered by a small disc vacuum filter to obtain a precursor with a water content of 38 wt%.

[0104] (3) The precursor prepared above was placed in an oven at 350°C for a first drying treatment for 30 hours to obtain ceramic nanofiber tube shell S3.

[0105] Example 4

[0106] The ceramic nanofiber tube shell was prepared according to the method of Example 1, except that in step (2), the binder A1 used was 18 kg.

[0107] The remaining steps are the same as in Example 1, and ceramic nanofiber tube shell S4 is obtained.

[0108] Example 5

[0109] The ceramic nanofiber tube shell was prepared according to the method of Example 1, except that in step (2), the additive used was 1.62 kg.

[0110] The remaining steps are the same as in Example 1, and ceramic nanofiber tube shell S5 is obtained.

[0111] Comparative Example 1

[0112] The ceramic nanofiber tube shell was prepared according to the method of Example 1, except that in step (2), the binder A1 was replaced with an equal mass of ethanol.

[0113] The remaining steps are the same as in Example 1, and the ceramic nanofiber tube shell DS1 is obtained.

[0114] Comparative Example 2

[0115] The ceramic nanofiber tube shell was prepared according to the method of Example 1, except that in step (2), the waste aluminosilicate fiber 1 was replaced with an equal mass of waste aluminosilicate fiber 2.

[0116] The remaining steps are the same as in Example 1, and the ceramic nanofiber tube shell DS2 is obtained.

[0117] Comparative Example 3

[0118] The ceramic nanofiber tube shell was prepared according to the method of Example 1, except that in step (2), filtration was not performed, and the water content of the precursor was 45 wt%.

[0119] The remaining steps are the same as in Example 1, and the ceramic nanofiber tube shell DS3 is obtained.

[0120] Test Example 1

[0121] The ceramic nanofiber tube shells prepared in the examples and comparative examples were subjected to performance tests, and the specific test results are shown in Table 1.

[0122] The test method for bulk density is as follows: refer to GB / T 17911-2018 "Test Methods for Refractory Fiber Products";

[0123] The test method for compressive strength is as follows: refer to GB / T 13480-2014 "Determination of compressive properties of thermal insulation products for building".

[0124] The test method for thermal conductivity (hot surface temperature of 600℃) is as follows: refer to YB / T 4130-2005 "Test Method for Thermal Conductivity of Refractory Materials (Water Flow Plate Method)".

[0125] Table 1

[0126] Example number <![CDATA[Volume density, kg / m 3 > Pressure resistance, kPa Thermal conductivity, W / mK Example 1 153 205 0.061 Example 2 168 209 0.058 Example 3 185 212 0.046 Example 4 144 194 0.068 Example 5 150 199 0.070 Comparative Example 1 141 186 0.074 Comparative Example 2 137 183 0.079 Comparative Example 3 132 181 0.085

[0127] As can be seen from the results in Table 1, the method provided by this invention for preparing ceramic nanofiber tube shells can not only effectively improve the comprehensive utilization rate of waste aluminosilicate cotton, but also obtain ceramic nanofiber tube shell products with excellent performance.

[0128] Test Example 2

[0129] The ceramic nanofiber tube shell prepared in Example 3 was applied to the insulation layer of a 319-meter DN400 medium-pressure steam pipeline from the No. 3 catalytic workshop to the No. 2 catalytic workshop of China Petroleum & Chemical Corporation Beijing Yanshan Branch. After the modification, the insulation structure of the pipeline is a 35mm thick ceramic nanofiber tube shell + a 15mm thick aluminosilicate fiber blanket + a 100mm thick aluminosilicate tube shell. The heat dissipation area, heat loss and energy saving and emission reduction before and after the modification were calculated respectively.

[0130] (1) After the modification, the insulation layer thickness changed from 200mm to 150mm, the pipeline outer diameter was 426mm, and the heat dissipation area before the modification was 827.37m². 2After the modification, the heat dissipation area is 727.21m². 2 Based on an average annual operating time of 8400 hours, this reduces heat loss by 4920 GJ per year; furthermore, after the energy-saving renovation, the average heat loss of the aforementioned insulated pipelines is reduced from 323.11 W / m. 2 Reduced to 143.87W / m 2 This represents a decrease of 55.47%.

[0131] (2) According to the enthalpy-entropy diagram, the enthalpy of medium-pressure steam at 3.6 MPa and 400℃ is 3219.57 kJ / kg. Reducing heat loss is equivalent to saving 1528.15 tons of medium-pressure steam. The price of medium-pressure steam is 270 yuan / ton, which can save 412,600 yuan per year.

[0132] (3) According to SH / T 5000-2011, the average lower heating value of standard oil is 41868 kJ / kg. Reducing heat loss is equivalent to saving 117.51 ​​tons of standard oil. The CO2 emission factor of standard oil is 71.1 kg / kJ, that is, the CO2 emission per ton of standard oil is 2.973 tons. Due to energy saving and reduced fuel consumption, China Petroleum & Chemical Corporation Beijing Yanshan Branch reduces carbon dioxide emissions by 349.36 tons per year.

[0133] (4) The insulation renovation of the DN400 medium-pressure steam line from the No. 3 catalytic workshop to the No. 2 catalytic workshop of China Petroleum & Chemical Corporation Beijing Yanshan Branch reduced the comprehensive production cost of insulation materials by RMB 256,500 during the 9-month application period; at the same time, it reduced carbon dioxide emissions by about 262 tons due to the saving of steam production fuel.

[0134] The present invention provides, by way of example, X-ray diffraction patterns and scanning electron microscope images of novel aluminosilicate fibers and waste aluminosilicate fibers 1 provided by the present invention, as shown in the figures below. Figure 1 and Figure 2 .

[0135] in, Figure 1 X-ray diffraction patterns of novel aluminosilicate fibers and waste aluminosilicate fibers 1 provided by this invention. Figure 2 Figure 2a shows a scanning electron microscope (SEM) image of a brand new aluminosilicate fiber and a waste aluminosilicate fiber 1 provided by the present invention. Figure 2b shows a scanning electron microscope (SEM) image of a brand new aluminosilicate fiber and a waste aluminosilicate fiber 1 provided by the present invention.

[0136] from Figure 1 As can be seen from the data, the waste aluminum silicate fiber provided by this invention does not have obvious absorption peaks, indicating that the aluminum silicate cotton provided by this invention is basically non-crystalline and belongs to amorphous ordinary aluminum silicate cotton.

[0137] from Figure 2As can be seen from the above, the waste aluminum silicate fiber provided by the present invention has a relatively smooth surface, is cylindrical, and the independent whole fiber is rod-shaped with very little natural bending and uniform thickness. The fiber dispersion is relatively dispersed and partially intersecting, with narrow gaps between the fiber rods and no fiber fusion phenomenon.

[0138] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing ceramic nanofiber tube shells, characterized in that, The method includes: (1) The waste aluminosilicate fibers are pretreated to obtain fiber raw materials with an average length of 5-50 mm; the waste aluminosilicate fibers contain 0.37 wt% Fe2O3, 35-45 wt% Al2O3, and 45-55 wt% SiO2. (2) The fiber raw material, additive and binder are contacted and mixed to obtain a first mixture, and the first mixture is molded to obtain a precursor; the molding conditions are controlled so that the water content of the precursor is 32-38 wt%; relative to 1g of the fiber raw material, the amount of additive is 0.033-0.084g and the amount of binder is 0.11-0.67g; The additive is selected from at least one of sodium silicate, silica sol, and aluminum sol. The binder is prepared by using an organic surfactant and an inorganic dispersant in a mass ratio of 1:0.3-0.5; the organic surfactant is an organic surfactant containing at least two groups selected from sulfonic acid group, sulfate ester group, amide group, hydroxyl group, ammonium group, and oxyethylene group; and the inorganic dispersant is selected from at least one of sodium tripolyphosphate, sodium hexametaphosphate, calcium lignosulfonate, and sodium lignosulfonate. (3) The precursor is subjected to a first drying treatment; The binder is prepared by a method comprising the following steps: S1. Dissolve ethanolamine and glucose in ethanol to obtain material I, and then react material I with catalyst I to obtain material II; S2. In the presence of propylene glycol and catalyst II, the material II and component A are subjected to contact reaction II to obtain an organic surfactant; wherein, component A is a fatty acid methyl ester or sodium fatty acid methyl ester sulfonate. S3. In the presence of water, the organic surfactant is mixed with hydrophobic nano-silica to obtain material III, and material III is mixed with an inorganic dispersant to obtain material II.

2. The method according to claim 1, wherein, In step (1), the pretreatment includes sequentially subjecting the waste aluminosilicate fibers to a first washing, a first soaking, and a second drying treatment; and / or In step (1), the solvent used for the first cleaning is water, and the first cleaning is performed 1-5 times; and / or In step (1), the conditions for the first soaking include at least: a time of 20-30 hours; and / or In step (1), the conditions for the second drying process include at least the following: a temperature of 100-150°C and a time of 20-30 hours.

3. The method according to claim 1 or 2, wherein, In step (2), the conditions for contact mixing include at least: a temperature of 18-30°C and a time of 30-60 min.

4. The method according to claim 1 or 2, wherein, In step (2), the molding process conditions include at least the following: temperature of 18-30℃, pressure of 10-30MPa, and time of 10-30min.

5. The method according to claim 1 or 2, wherein, In step (3), the conditions for the first drying process include at least the following: a temperature of 110-350°C and a time of 24-30h.

6. A ceramic nanofiber tube shell prepared by the method according to any one of claims 1-5.

7. The ceramic nanofiber tube shell according to claim 6, wherein, The bulk density of the ceramic nanofiber shell is ≤200 kg / m³. 3 ; and / or The ceramic nanofiber tube shell has a pressure resistance of ≥200 kPa; and / or The thermal conductivity of the ceramic nanofiber tube shell at a hot surface temperature of 600℃ is ≤0.065w / mk.

8. The application of the ceramic nanofiber tube shell according to claim 6 or 7 in thermal insulation materials.

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