Aerogel composite thermal insulation material for steam pipes and method of making same

Abstract

The application belongs to the technical field of composite thermal insulation materials, and specifically provides an aerogel composite thermal insulation material for steam pipelines and a preparation method thereof. The preparation method of the aerogel composite thermal insulation material for steam pipelines comprises the following steps: S1, tetraethyl orthosilicate, anhydrous ethanol, water and N,N-dimethylformamide are mixed, and a sol is prepared after heating and stirring after pH adjustment; S2, modified zirconium tungstate is added into the sol, the sol is injected into a mold, modified glass wool is placed, and a silica sol-gel / glass wool composite material is prepared by using a vacuum impregnation method; and S3, the silica sol-gel / glass wool composite material is aged, cleaned with ethanol, and dried by using CO2 supercritical drying to obtain the aerogel composite thermal insulation material. The aerogel composite thermal insulation material for steam pipelines prepared by the application has a low thermal conductivity and good mechanical properties.

Description

Technical Field

[0001] This application belongs to the field of composite insulation materials technology, and in particular relates to an aerogel composite insulation material for steam pipelines and its preparation method. Background Technology

[0002] Steam pipelines, as key facilities for industrial heat energy transportation, experience significant heat loss during transport, leading to reduced energy efficiency and increased energy consumption. Therefore, highly efficient insulation materials are essential. However, traditional insulation materials such as rock wool, aluminum silicate fiber, and glass wool often contain organic binders, suffer from poor long-term thermal stability, and lack sufficient hydrophobicity, requiring regular replacement or maintenance. Aerogels, on the other hand, possess a unique nanoscale pore structure with high porosity, large specific surface area, and an average pore size smaller than the mean free path of gas molecules. This inhibits convective heat transfer within the material and restricts the free movement of gas molecules. Furthermore, the multiple heat transfer mechanisms of aerogels create a coupled heat transfer effect, resulting in excellent thermal insulation and flame retardant properties, making aerogels highly promising for applications.

[0003] However, aerogel materials themselves have low strength and high brittleness, limiting their direct use. In practical applications, aerogels are usually composited with fiber materials to create various products to improve their mechanical properties. Aerogel felt is made by compositing aerogel with matrix materials such as glass wool and ceramic fibers. Glass wool, with its good flexibility, high tensile strength, and low cost, has become one of the most commonly used reinforcing fibers in aerogel composites. However, insufficient interfacial bonding between fibers and aerogel leads to easy detachment and powdering of aerogel on the fiber surface; in addition, due to the size difference between fibers and aerogel, the fiber surface cannot be completely covered by aerogel, and the resulting voids provide pathways for heat transfer; secondly, the difference in the coefficients of thermal expansion between fibers and aerogel leads to interfacial stress concentration under thermal cycling, generating thermal stress at the interface during repeated heating and cooling, accelerating interfacial debonding and material failure. Summary of the Invention

[0004] To address the aforementioned issues and further improve the interfacial bonding between fibers and aerogel, this application provides an aerogel composite insulation material for steam pipelines and its preparation method.

[0005] This application first provides a method for preparing an aerogel composite insulation material for steam pipes, comprising the following steps: S1, mixing tetraethyl orthosilicate, anhydrous ethanol, water, and N,N-dimethylformamide, adjusting the pH, and heating and stirring to obtain a sol; S2, adding modified zirconium tungstate to the sol, ultrasonically dispersing and adjusting the pH, injecting the sol into a mold, placing modified glass wool, and using a vacuum impregnation method to obtain a silica alcohol gel / glass wool composite material; S3, aging the silica alcohol gel / glass wool composite material sequentially in ethanol, an ethanol solution of tetraethyl orthosilicate, and an ethanol solution of hexamethyldisilazane, washing with ethanol after aging, and finally using supercritical CO2 drying to obtain the aerogel composite insulation material.

[0006] Furthermore, in S1, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol, water, and N,N-dimethylformamide is 1:(9-11):(3.5-4):0.8.

[0007] Furthermore, in S2, the preparation method of modified zirconium tungstate includes the following steps: impregnating nano-zirconium tungstate in an aqueous solution of diammonium hydrogen phosphate with an equal volume, and calcining the powder after it is just completely wetted to obtain modified zirconium tungstate.

[0008] Furthermore, the phosphate loading of the modified zirconium tungstate is 0.5-2 wt% of the nano-zirconium tungstate.

[0009] Furthermore, in S2, the molar ratio of modified zirconium tungstate nanoparticles to tetraethyl orthosilicate is 0.005-0.016:1.

[0010] Furthermore, in S2, the preparation method of modified glass wool includes the following steps: A1, dispersing nano-boehmite in deionized water, adjusting the pH, and then heating and stirring to obtain a sol; A2, completely immersing glass wool in the sol, and fully impregnating it under vacuum conditions to obtain modified glass wool.

[0011] Furthermore, in S2, the thickness of the modified glass wool is 4-5 mm.

[0012] Furthermore, in S3, the supercritical CO2 drying conditions are a temperature of 40°C, a pressure of 15-25 MPa, and a time of 60-120 min.

[0013] Furthermore, this application provides an aerogel composite insulation material for steam pipelines, which is prepared using the above-described method.

[0014] Furthermore, this application provides an application of an aerogel composite insulation material for steam pipelines, which is applied to the insulation layer of steam pipelines.

[0015] Compared with the prior art, this application has the following beneficial effects: 1. This application modifies the surface of zirconium tungstate by phosphorylation, introducing phosphate groups onto its surface. These phosphate groups interact with the Zr atoms on the zirconium tungstate surface. 4+ and W 6+ Ions have strong coordination ability and can form stable chemical bonds, which effectively improves the dispersion of zirconium tungstate in silica aerogel matrix. At the same time, zirconium tungstate has negative thermal expansion characteristics, which can counteract the positive thermal expansion of aerogel matrix during repeated heating and cooling, reduce the accumulation of thermal stress at the interface, and enhance interfacial bonding.

[0016] 2. This application modifies the surface of glass wool with nano-boehmite, introducing an active interface layer rich in aluminum hydroxyl groups onto the surface of the glass wool. This layer can undergo a condensation reaction with Si-OH in the silica aerogel skeleton to form Al-O-Si covalent bonds, firmly connecting the glass wool to the aerogel skeleton. Simultaneously, it can react with phosphate groups on the surface of zirconium tungstate phosphate to form PO-Al chemical bonds, further enhancing the interfacial bonding. Moreover, during the service of steam pipelines, nano-boehmite transforms into γ-Al2O3, which has high thermal stability, thereby significantly improving the thermal stability and mechanical properties of the composite material under thermal cycling conditions such as steam pipelines. Attached Figure Description

[0017] Figure 1 The image shows the infrared spectrum of the modified zirconium tungstate from Example 2.

[0018] Figure 2 The thermal conductivity diagrams are for Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0019] To make the inventive objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. Obviously, the described embodiments are only a portion of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only” is used, in which case another component may be added.

[0022] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0023] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0024] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0025] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0026] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0027] Example 1 The preparation method of the aerogel composite insulation material for steam pipelines in this embodiment is as follows: S1, 0.5 mol tetraethyl orthosilicate, 4.5 mol anhydrous ethanol, 1.75 mol water and 0.4 mol N,N-dimethylformamide were added to a beaker, and 0.1 mol / L dilute hydrochloric acid was added dropwise to adjust the pH to 3. The mixture was heated and stirred in a 50℃ constant temperature water bath for 3 hours to obtain a sol.

[0028] S2, 2.5 mmol of modified zirconium tungstate nanoparticles were added to the sol and ultrasonically dispersed for 30 min. After adjusting the pH to 8 by adding 1 mol / L ammonia, the sol was injected into a mold, and a 4 mm thick layer of modified glass wool was placed along the length of the mold. The sol was then vacuum impregnated and allowed to stand for 3 h to obtain the silica alcohol gel / glass wool composite material.

[0029] S3, the silica alcohol gel / glass wool composite material was immersed in a 50°C ethanol solution and aged in a closed water bath for 24 hours, followed by aging in a 20 vol% tetraethyl orthosilicate ethanol solution at 50°C for 24 hours. After aging, it was washed three times with ethanol. Then, it was modified in a hexamethyldisilazane ethanol solution at 50°C in a closed water bath for 24 hours. After modification, it was washed three times with ethanol. Finally, it was dried using supercritical CO2. The material was placed in a pressure vessel, and the air in the vessel was replaced with CO2 three times. Then, CO2 was pumped into the vessel until the pressure reached 7.4 MPa. After that, the temperature of the vessel was increased. When the pressure and temperature reached the target values ​​of 15 MPa and 40°C, CO2 was recycled and dried for 75 minutes to obtain the aerogel composite insulation material.

[0030] The preparation method of the modified zirconium tungstate in this embodiment is as follows: 3g of nano-zirconium tungstate was impregnated in an aqueous solution of diammonium hydrogen phosphate, with a phosphate loading of 0.5% of the nano-zirconium tungstate. After the powder was just completely wetted, it was calcined in static air at 500℃ for 3 hours to obtain modified zirconium tungstate.

[0031] The modified glass wool in this embodiment is prepared as follows: A1. Disperse 10g of nano-boehmite in 100mL of deionized water, adjust the pH to 4 with dilute nitric acid, and stir at 85℃ to obtain a sol.

[0032] A2. The glass wool is completely immersed in the above sol and kept under vacuum for 30 minutes to allow the sol to fully wet the fibers, thus obtaining modified glass wool.

[0033] Example 2 The preparation method of the aerogel composite insulation material for steam pipelines in this embodiment is as follows: S1. Add 0.5 mol tetraethyl orthosilicate, 5.5 mol anhydrous ethanol, 2 mol water, and 0.4 mol N,N-dimethylformamide to a beaker, adjust the pH to 3 by adding 0.1 mol / L dilute hydrochloric acid dropwise, and heat and stir in a 50℃ constant temperature water bath for 3 hours to obtain a sol.

[0034] S2, 8 mmol of modified zirconium tungstate nanoparticles were added to the sol and ultrasonically dispersed for 30 min. After adjusting the pH to 8 by adding 1 mol / L ammonia, the sol was injected into the mold, and modified glass wool with a thickness of 5 mm was placed along the length of the mold. The sol was then prepared by vacuum impregnation and allowed to stand for 3 h. The silica alcohol gel / glass wool composite material was then obtained.

[0035] S3. The silica alcohol gel / glass wool composite material was immersed in a 50°C ethanol solution and aged in a closed water bath for 24 hours. Then, it was aged in a 20 vol% tetraethyl orthosilicate ethanol solution at 50°C for another 24 hours. After aging, it was washed three times with ethanol. Next, it was modified in a hexamethyldisilazane ethanol solution at 50°C in a closed water bath for 24 hours. After modification, it was washed three times with ethanol. Finally, it was supercritically dried with CO2. The material was placed in a pressure vessel, and the air inside the vessel was replaced with CO2 in three stages. CO2 was then pumped into the vessel until the pressure reached 7.4 MPa, after which the vessel temperature was increased. When the pressure and temperature reached the target values ​​of 25 MPa and 40°C, respectively, CO2 was recycled, and the material was dried for 1 hour to obtain the aerogel composite insulation material.

[0036] The preparation method of the modified zirconium tungstate in this embodiment is as follows: 3g of nano-zirconium tungstate was impregnated in an aqueous solution of diammonium hydrogen phosphate, with a phosphate loading of 2% of the nano-zirconium tungstate. After the powder was just completely wetted, it was calcined in a static air atmosphere at 500℃ for 3 hours to obtain modified zirconium tungstate.

[0037] The modified glass wool in this embodiment is prepared as follows: A1. Disperse 10g of nano-boehmite in 100mL of deionized water, adjust the pH to 4 with dilute nitric acid, and stir at 85℃ to obtain a sol.

[0038] A2. The glass wool is completely immersed in the above sol and kept under vacuum for 30 minutes to allow the sol to fully wet the fibers, thus obtaining modified glass wool.

[0039] Example 3 The preparation method of the aerogel composite insulation material for steam pipelines in this embodiment is as follows: S1, 0.5 mol tetraethyl orthosilicate, 4.5 mol anhydrous ethanol, 1.75 mol water and 0.4 mol N,N-dimethylformamide were added to a beaker, and 0.1 mol / L dilute hydrochloric acid was added dropwise to adjust the pH to 3. The mixture was heated and stirred in a 50℃ constant temperature water bath for 3 hours to obtain a sol.

[0040] S2, 5 mmol of modified zirconium tungstate nanoparticles were added to the sol and ultrasonically dispersed for 30 min. After adjusting the pH to 8 by adding 1 mol / L ammonia, the sol was injected into the mold, and modified glass wool with a thickness of 5 mm was placed along the length of the mold. The sol was then prepared by vacuum impregnation and allowed to stand for 3 h. The silica alcohol gel / glass wool composite material was then obtained.

[0041] S3, the silica alcohol gel / glass wool composite material was immersed in a 50°C ethanol solution and aged in a closed water bath for 24 hours. Then, it was aged in a 20 vol% tetraethyl orthosilicate ethanol solution at 50°C for 24 hours. After aging, it was washed three times with ethanol. Then, it was modified in a hexamethyldisilazane ethanol solution at 50°C in a closed water bath for 24 hours. After modification, it was washed three times with ethanol. Finally, it was dried using supercritical CO2. The material was placed in a pressure vessel, and the air in the vessel was replaced with CO2 three times. Then, CO2 was pumped into the vessel until the pressure reached 7.4 MPa. After that, the temperature of the vessel was increased. When the pressure and temperature reached the target values ​​of 15 MPa and 40°C, CO2 was recycled and dried for 120 minutes to obtain the aerogel composite insulation material.

[0042] The preparation method of the modified zirconium tungstate in this embodiment is as follows: 3g of nano-zirconium tungstate was impregnated in an aqueous solution of diammonium hydrogen phosphate, with a phosphate loading of 1.5% of the nano-zirconium tungstate. After the powder was just completely wetted, it was calcined in static air at 500℃ for 3 hours to obtain modified zirconium tungstate.

[0043] The modified glass wool in this embodiment is prepared as follows: A1. Disperse 10g of nano-boehmite in 100mL of deionized water, adjust the pH to 4 with dilute nitric acid, and stir at 85℃ to obtain a sol.

[0044] A2. The glass wool is completely immersed in the above sol and kept under vacuum for 30 minutes to allow the sol to fully wet the fibers, thus obtaining modified glass wool.

[0045] Comparative Example 1 The preparation method of the aerogel composite insulation material for steam pipelines in this comparative example is as follows: S1. Add 0.5 mol tetraethyl orthosilicate, 5.5 mol anhydrous ethanol, 2 mol water, and 0.4 mol N,N-dimethylformamide to a beaker, adjust the pH to 3 by adding 0.1 mol / L dilute hydrochloric acid dropwise, and heat and stir in a 50℃ constant temperature water bath for 3 hours to obtain a sol.

[0046] S2, 8 mmol of modified zirconium tungstate nanoparticles were added to the sol and ultrasonically dispersed for 30 min. After adjusting the pH to 8 by adding 1 mol / L ammonia, the sol was injected into a mold, and glass wool with a thickness of 5 mm was placed along the length of the mold. The sol was then prepared by vacuum impregnation and allowed to stand for 3 h.

[0047] S3. The silica alcohol gel / glass wool composite material was immersed in a 50°C ethanol solution and aged in a closed water bath for 24 hours. Then, it was aged in a 20 vol% tetraethyl orthosilicate ethanol solution at 50°C for another 24 hours. After aging, it was washed three times with ethanol. Next, it was modified in a hexamethyldisilazane ethanol solution at 50°C in a closed water bath for 24 hours. After modification, it was washed three times with ethanol. Finally, it was supercritically dried with CO2. The material was placed in a pressure vessel, and the air inside the vessel was replaced with CO2 in three stages. CO2 was then pumped into the vessel until the pressure reached 7.4 MPa, after which the vessel temperature was increased. When the pressure and temperature reached the target values ​​of 25 MPa and 40°C, respectively, CO2 was recycled, and the material was dried for 1 hour to obtain the aerogel composite insulation material.

[0048] The modified zirconium tungstate in this comparative example is prepared as follows: 3g of nano-zirconium tungstate was impregnated in an aqueous solution of diammonium hydrogen phosphate, with a phosphate loading of 2% of the nano-zirconium tungstate. After the powder was just completely wetted, it was calcined in a static air atmosphere at 500℃ for 3 hours to obtain modified zirconium tungstate.

[0049] Comparative Example 2 The preparation method of the aerogel composite insulation material for steam pipelines in this comparative example is as follows: S1. Add 0.5 mol tetraethyl orthosilicate, 5.5 mol anhydrous ethanol, 2 mol water, and 0.4 mol N,N-dimethylformamide to a beaker, adjust the pH to 3 by adding 0.1 mol / L dilute hydrochloric acid dropwise, and heat and stir in a 50℃ constant temperature water bath for 3 hours to obtain a sol.

[0050] S2, 8 mmol of zirconium tungstate nanoparticles were added to the sol and ultrasonically dispersed for 30 min. After adjusting the pH to 8 by adding 1 mol / L ammonia, the sol was injected into a mold, and glass wool with a thickness of 5 mm was placed along the length of the mold. The sol was then prepared by vacuum impregnation and allowed to stand for 3 h. The silica alcohol gel / glass wool composite material was then obtained.

[0051] S3. The silica alcohol gel / glass wool composite material was immersed in a 50°C ethanol solution and aged in a closed water bath for 24 hours. Then, it was aged in a 20 vol% tetraethyl orthosilicate ethanol solution at 50°C for another 24 hours. After aging, it was washed three times with ethanol. Next, it was modified in a hexamethyldisilazane ethanol solution at 50°C in a closed water bath for 24 hours. After modification, it was washed three times with ethanol. Finally, it was supercritically dried with CO2. The material was placed in a pressure vessel, and the air inside the vessel was replaced with CO2 in three stages. CO2 was then pumped into the vessel until the pressure reached 7.4 MPa, after which the vessel temperature was increased. When the pressure and temperature reached the target values ​​of 25 MPa and 40°C, respectively, CO2 was recycled, and the material was dried for 1 hour to obtain the aerogel composite insulation material.

[0052] Performance testing According to GB / T 34336-2017, the thermal conductivity of aerogel composite insulation materials at different temperatures was tested; the linear shrinkage rate of aerogel composite insulation materials was tested after heat treatment at 800℃ and 1000℃ for 1 hour respectively; the 50% deformation compressive strength of aerogel composite insulation materials was tested using an electronic universal testing machine. The sample dimensions were: length 80mm, width 80mm, and thickness 11mm; the coefficient of thermal expansion of aerogel composite insulation materials was determined using a thermal dilatometer.

[0053] Table 1. Performance test results of aerogel composite insulation materials in Examples 1-3 and Comparative Examples 1-2 Analyze Examples 1-3 and Comparative Examples 1-2, in conjunction with Table 1 and Figure 1 It can be seen that the synergistic effect of phosphorylated zirconium tungstate and boehmite-modified glass wool can effectively reduce the thermal conductivity and thermal expansion coefficient of the composite material, and improve the compressive strength and interfacial bonding force.

[0054] Analysis Table 1 and Figure 2 Compared to Examples 1-3, the aerogel composite insulation material prepared in Comparative Example 1, with its glass wool not modified by boehmite, cannot form Al-O-Si covalent bonds with the silica aerogel skeleton, resulting in weak interfacial bonding and a significant decrease in compressive strength. Compared to Examples 1-3, the aerogel composite insulation material prepared in Comparative Example 2, with its zirconium tungstate not modified by phosphorylation, lacks phosphate groups on the particle surface, making it prone to sedimentation in the sol. The negative thermal expansion effect cannot be effectively utilized, and the agglomerated particles form stress concentration points in the aerogel skeleton, thus increasing the coefficient of thermal expansion and weakening the compressive strength of Comparative Example 2.

[0055] analyze Figure 1 It can be observed that the modified zirconium tungstate, compared to zirconium tungstate, has a 1020 cm⁻¹... -1Absorption peaks for PO stretching vibrations were observed at 950 cm⁻¹, with both peaks around 950 cm⁻¹. -1 The presence of a stretching vibration absorption peak at W=O indicates the successful synthesis of modified zirconium tungstate.

[0056] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing an aerogel composite insulation material for steam pipelines, characterized in that, The process includes the following steps: S1, tetraethyl orthosilicate, anhydrous ethanol, water, and N,N-dimethylformamide are mixed, the pH is adjusted, and the mixture is heated and stirred to obtain a sol; S2, modified zirconium tungstate is added to the sol, ultrasonically dispersed, and the pH is adjusted before injecting the sol into a mold and placing modified glass wool. A silica alcohol gel / glass wool composite material is obtained by vacuum impregnation; S3, the silica alcohol gel / glass wool composite material is aged sequentially in ethanol, an ethanol solution of tetraethyl orthosilicate, and an ethanol solution of hexamethyldisilazane. After aging, it is washed with ethanol and finally dried using supercritical CO2 to obtain an aerogel composite insulation material.

2. The method for preparing an aerogel composite insulation material for steam pipelines according to claim 1, characterized in that, In S1, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol, water, and N,N-dimethylformamide is 1:(9-11):(3.5-4):0.

8.

3. The method for preparing an aerogel composite insulation material for steam pipelines according to claim 1, characterized in that, In S2, the preparation method of modified zirconium tungstate includes the following steps: impregnating nano-zirconium tungstate in an aqueous solution of diammonium hydrogen phosphate with an equal volume, and calcining the powder after it is just completely wetted to obtain modified zirconium tungstate.

4. The method for preparing an aerogel composite insulation material for steam pipelines according to claim 3, characterized in that, The phosphate loading of the modified zirconium tungstate is 0.5-2 wt% of the nano-zirconium tungstate.

5. The method for preparing an aerogel composite insulation material for steam pipelines according to claim 1, characterized in that, In S2, the molar ratio of modified zirconium tungstate nanoparticles to tetraethyl orthosilicate is 0.005-0.016:

1.

6. The method for preparing an aerogel composite insulation material for steam pipelines according to claim 1, characterized in that, In step S2, the preparation method of modified glass wool includes the following steps: A1, dispersing nano-boehmite in deionized water, adjusting the pH, and then heating and stirring to obtain a sol; A2, completely immersing glass wool in the sol, and fully impregnating it under vacuum conditions to obtain modified glass wool.

7. The method for preparing an aerogel composite insulation material for steam pipelines according to claim 1, characterized in that, In S2, the thickness of the modified glass wool is 4-5 mm.

8. The method for preparing an aerogel composite insulation material for steam pipelines according to claim 1, characterized in that, In S3, the supercritical CO2 drying conditions are a temperature of 40°C, a pressure of 15-25 MPa, and a time of 60-120 min.

9. An aerogel composite insulation material for steam pipelines, characterized in that, It is prepared by any one of the preparation methods described in claims 1-8.

10. An application of an aerogel composite insulation material for steam pipelines, characterized in that, The aerogel composite insulation material for steam pipelines as described in claim 9 is applied to the insulation layer of steam pipelines.

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