Inorganic composite heat-insulating material for high-temperature liquid sodium pipeline and preparation method thereof

Abstract

The application discloses a kind of inorganic composite heat-insulating materials for high-temperature liquid sodium pipeline and preparation method thereof, belong to inorganic composite heat-insulating material, the formula of the inorganic composite heat-insulating material is: with alumina fiber cloth as matrix, according to weight fraction, further include the following raw materials: hollow ceramic fiber 25-35 parts, gamma-alumina powder 30-40 parts, metakaolin 10-15 parts, mica flake 5-10 parts, water glass 3-5 parts, sodium hydroxide 1-3 parts, polyvinyl alcohol 5 parts and sodium dodecylsulfonate 2-3 parts.By synergistic effect between the above raw materials, then using mechanical force and microwave energy, inorganic heat-insulating material with curling ability and high temperature is not easy to deform is prepared under low energy consumption, can be used in liquid alkali metal system, such as sodium-cooled fast reactor high-temperature equipment heat preservation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic composite thermal insulation materials, and particularly relates to an inorganic composite thermal insulation material for high-temperature liquid sodium pipelines and a preparation method thereof. BACKGROUND

[0002] At present, the thermal insulation materials for high-temperature pipelines of energy systems are mainly prepared from soft and curlable inorganic cotton, such as aluminum silicate cotton, glass cotton or rock wool. These materials are usually prepared from one main material, and the pore size formed in the material is relatively single. For cotton felt materials, the main pore is a through hole with a large size, which is very easy to deform at high temperature, and a large gap is generated between the thermal insulation pipeline and the thermal insulation material, resulting in serious heat loss and loss of thermal insulation effect. Especially when used in a sodium-cooled fast reactor, liquid sodium can easily penetrate into the cotton felt material, causing a safety hazard. In recent years, the thermal conductivity of aerogel felt thermal insulation materials is very low, and the thermal insulation capacity is very excellent; however, the matrix structure of the aerogel felt thermal insulation material is mainly nano-pores, and the penetration amount of liquid sodium is still large. In particular, the nano-aerogel powder has a high activity, and can directly react with liquid alkali metals such as sodium, which can cause a sodium fire and other major safety hazards. At present, there is no thermal insulation material for the sodium-cooled fast reactor.

[0003] Therefore, it is urgent to develop a new type of inorganic thermal insulation material with excellent high-temperature thermal insulation capacity and no obvious reaction with liquid sodium. SUMMARY

[0004] In view of the urgent demand for thermal insulation materials for sodium-cooled fast reactors and the problems described above, the present application provides an inorganic composite thermal insulation material with curlable micro-nano multi-level pores and a preparation method thereof on the basis of the existing high-temperature inorganic thermal insulation material through formula innovation and process innovation.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] One of the technical schemes of the present application is as follows:

[0007] An inorganic composite thermal insulation material for high-temperature liquid sodium pipelines, taking alumina fiber cloth as a matrix, and comprising the following raw materials in parts by weight:

[0008] 25-35 parts of hollow ceramic fiber, 30-40 parts of gamma-alumina powder, 10-15 parts of metakaolin, 5-10 parts of mica sheet, 3-5 parts of water glass, 1-3 parts of sodium hydroxide, 5 parts of polyvinyl alcohol and 2-3 parts of sodium dodecyl sulfonate.

[0009] Beneficial effects: through the interaction between the raw materials defined in the application, an inorganic composite thermal insulation material with micro-nano multi-stage pores for high-temperature liquid sodium pipeline, which can be curled, is prepared, the material has excellent high-temperature insulation capacity, and does not have obvious reaction with liquid sodium. The roles of the raw materials in the inorganic thermal insulation material formula defined in the application are as follows: the hollow ceramic fiber material mainly plays a toughening role, a suitable aspect ratio is selected, so that the prepared material has certain curling performance; the γ-alumina agglomerated powder mainly plays a role in filling and improving the deformation resistance of the coiled material, and the nano-micron closed pores and the cavities constructed together with the fibers are beneficial to the blocking of heat convection, so that low thermal conductivity is obtained; the mica sheet plays a toughening role, and floats on the surface during the molding process, also plays a role in inhibiting radiation heat transfer and closing the surface opening, and further improves the thermal insulation capacity; the metakaolin, water glass and sodium hydroxide can play an inorganic polymerization role, and the coating on the surface of the γ-alumina agglomerated powder can play a role in closing the pores and increasing the bonding force of the matrix.

[0010] Preferably, the following raw materials are included according to weight parts:

[0011] Hollow ceramic fiber 35 parts, γ-alumina powder 30 parts, metakaolin 12 parts, mica sheet 10 parts, water glass 3 parts, sodium hydroxide 2 parts, polyvinyl alcohol 5 parts and sodium dodecyl sulfonate 3 parts.

[0012] Preferably, the following raw materials are included according to weight parts:

[0013] Hollow ceramic fiber 25 parts, γ-alumina powder 40 parts, metakaolin 15 parts, mica sheet 5 parts, water glass 5 parts, sodium hydroxide 3 parts, polyvinyl alcohol 5 parts and sodium dodecyl sulfonate 2 parts.

[0014] Preferably, it is characterized in that,

[0015] The hollow ceramic fiber includes hollow alumina ceramic fiber or hollow mullite ceramic fiber.

[0016] Preferably,

[0017] The mica sheet is black mica or gold mica.

[0018] Preferably, the aspect ratio of the hollow ceramic fiber is (2-5) cm:(1-5) μm;

[0019] The γ-alumina powder is an agglomerate of 20-40 μm;

[0020] The diameter of the mica sheet is 50-70 μm, and the thickness is less than 5 μm.

[0021] The second technical scheme of the application:

[0022] A preparation method of an inorganic composite thermal insulation material for high-temperature liquid sodium pipeline, comprising the following steps:

[0023] According to the weight fraction of the above-mentioned raw materials, the raw materials are weighed and mixed;

[0024] The mixed raw materials are prepared into the inorganic composite thermal insulation material by using the alumina fiber cloth as the matrix and combining the flow casting and microwave heating treatment.

[0025] Preferably, the preparation method specifically comprises the following steps:

[0026] Water and sodium dodecyl sulfonate are added to the hollow ceramic fiber to obtain a ceramic fiber dispersion liquid;

[0027] The metakaolin, water glass, sodium hydroxide, gamma-alumina powder and water are mixed and stirred to obtain a ceramic microbead slurry;

[0028] The ceramic fiber dispersion liquid, the ceramic microbead slurry, the mica sheet, the polyvinyl alcohol and the water are mixed and stirred to prepare a slurry;

[0029] The slurry is dehydrated to a water content of 50%, the alumina fiber cloth is used as the matrix, the flow casting is combined with the microwave heating treatment, and then drying is performed to prepare the inorganic composite thermal insulation material.

[0030] Preferably, the parameter conditions in the flow casting process are that the distance between the doctor blade and the substrate is controlled to be 8-12 mm, the pressure of the doctor blade is controlled to be 0.8-1.2 MPa, and the speed of the flow casting is 1-2 m / min.

[0031] Preferably, the parameter conditions in the microwave heating process are that the microwave frequency is 2.45 GHz, the microwave heating power is 60 kW, the microwave drying time is 20-25 min, and the vacuum degree is 10-20 Pa.

[0032] Preferably, the parameter conditions in the drying process are that:

[0033] The drying is performed to a water content of 5%-10%, wherein the drying temperature is 120-150 DEG C, and the drying time is 8-10 h.

[0034] Compared with the prior art, the present application has the following advantages and technical effects:

[0035] The present application realizes the inorganic thermal insulation material with the curling ability and the high-temperature deformation resistance (i.e., the size is stable after the high-temperature thermal insulation treatment, i.e., the linear shrinkage is less than 2%) under the low energy consumption by the compounding of the alumina-based fiber, the alumina agglomerated powder and the flaky powder, the comprehensive play of the roles of different raw materials, and the mechanical force and the microwave energy, and can be used for designing the liquid alkali metal system, such as the thermal insulation of the high-temperature equipment of the sodium-cooled fast reactor. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which form a part of this application, are intended to provide further understanding of the application and are incorporated herein in their entirety. The drawings include an illustration of the preferred embodiment of the application, and are used to explain the application, but are not to be considered as limiting the application. In the drawings:

[0037] Figure 1 SEM image of the inorganic composite thermal insulation material prepared for Example 1 of the present application. DETAILED DESCRIPTION

[0038] The detailed description set forth below of various illustrative embodiments explains the principles of the application and the best mode presently contemplated by the inventors for carrying out the application. It will be appreciated, however, that the detailed description is not intended to limit the application to the particular embodiments described.

[0039] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, the use of the term "about" in relation to a value or a range of values is intended to include each and every value falling within the range and each and every value falling within the range, unless otherwise specifically indicated. Each and every value falling within the range and each and every value falling within the range, unless otherwise specifically indicated.

[0040] Unless defined otherwise, 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. Although any methods and materials similar or equivalent to those described herein can be used in the practice of the present application, the preferred methods and materials are described herein. All patents, patent applications, publications, and descriptions mentioned herein are incorporated by reference in their entirety for the disclosure and

[0041] Many modifications and variations of this application of the application can be made without departing from its spirit or scope, which will be apparent to those skilled in the art. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0042] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having", "contain", "containing", and the like are open-ended terms that are intended to mean including, but not limited to.

[0043] The present application discloses a kind of inorganic composite thermal insulation material with micro-nano multi-stage pore suitable for sodium-cooled fast reactor, according to weight parts, including the following raw materials:

[0044] Hollow ceramic fiber 25-35 parts, gamma-alumina powder 30-40 parts, metakaolin 10-15 parts, black mica sheet 5-10 parts, water glass 3-5 parts, sodium hydroxide 1-3 parts, polyvinyl alcohol 5 parts and sodium dodecyl sulfonate 2-3 parts.

[0045] In some preferred embodiments, the hollow ceramic fiber comprises hollow alumina fiber or hollow mullite fiber;

[0046] The mica sheet is black mica or phlogopite.

[0047] In some preferred embodiments, the diameter of the hollow ceramic fiber is 1-5 microns, and the length is 2-5 cm;

[0048] The gamma-alumina powder is an agglomerate of 20-40 microns;

[0049] The size of the mica sheet is 50-70 microns in diameter and less than 5 microns in thickness.

[0050] In addition, the application also discloses a preparation method of the rollable inorganic composite heat preservation material with micro-nano multi-level pores suitable for sodium-cooled fast reactors.

[0051] Water and sodium dodecyl sulfonate dispersant need to be added to the hollow ceramic fiber for pre-dispersion;

[0052] The metakaolin, water glass, sodium hydroxide and water are mixed, and then the gamma-alumina powder is added for mixing and stirring to obtain ceramic micro-bead slurry;

[0053] Finally, the dispersed ceramic fiber and the ceramic micro-bead slurry are mixed, the mica sheet and polyvinyl alcohol are added, and a large amount of water is added for stirring and mixing to prepare a slurry with a water content of 80-100% (when the dry weight of the slurry and the amount of added water are equal, the water content is 100%), and the slurry needs to be left to stand for 5-10 hours after uniform mixing; thereafter, stirring and standing are carried out reciprocally for three times;

[0054] After the prepared slurry is dehydrated to 50%, it is pumped into the barrel of a flow casting machine, an aluminum fiber cloth is used as the base body, flow casting is carried out, and through microwave heating, further dehydration is carried out to obtain a rollable green body with a water content of 20%-30% during the flow casting process;

[0055] The green body is further dried by hot air to finally obtain a rollable roll.

[0056] Unless otherwise specified, the "room temperature" in the application refers to 20-30 DEG C.

[0057] Unless otherwise specified, the "parts" in the application refer to mass parts.

[0058] The raw materials used in the present application are all purchased from the market. For example, the ceramic fiber is from 3M Company, the gamma-alumina powder is from Zibo Henghuan Aluminum Industry, the metakaolin is from Shanxi Jinyu Kelin Technology, the biotite sheet is from Hebei Huayuan Mining Industry, the water glass is from Shandong Yuda New Material, the sodium hydroxide is from Hebei Qingshen Chemical Industry, and the polyvinyl alcohol and sodium dodecyl sulfonate are from Aldrin Reagent.

[0059] The technical solutions of the present application are further illustrated by the following examples.

[0060] Example 1

[0061] A low-carbon preparation method of an inorganic composite thermal insulation material for high-temperature liquid sodium pipelines, comprising the following steps:

[0062] According to the weight fraction,

[0063] Hollow alumina ceramic fibers 35 parts (diameter 2 μm, length 3 cm) are weighed, and the hollow alumina ceramic fibers are stirred with 3 parts of sodium dodecyl sulfonate and 40 parts of water to obtain a ceramic fiber dispersion liquid;

[0064] After mixing 12 parts of metakaolin with 3 parts of water glass and 2 parts of sodium hydroxide with 50 parts of water, 30 parts of gamma-alumina agglomerated powder is added and stirred to obtain a ceramic microbead slurry; wherein the particle size of the gamma-alumina agglomerated powder is 30 μm;

[0065] Finally, the ceramic fiber dispersion liquid and the ceramic microbead slurry are mixed, 10 parts of biotite sheet (diameter 60 μm, thickness 3 μm) and 5 parts of polyvinyl alcohol are added to prepare a slurry with a water content of 90%, and the slurry is uniformly mixed and then left to stand for 10 h; thereafter, stirring and standing are repeated three times.

[0066] The prepared slurry is dehydrated to 50%, and then pumped into the barrel of a tape casting machine. Alumina fiber cloth is used as the substrate, and tape casting is performed. The distance between the scraper and the substrate is controlled to be 12 mm, the pressure of the scraper is controlled to be 1.2 MPa, and the speed of tape casting is 1.8 m / min. Microwave heating is further used for dehydration during the tape casting process. The microwave frequency used for microwave heating is 2.45 GHz, the microwave heating power is 60 kW, the microwave drying time is 25 min, and the vacuum degree is controlled to be 20 Pa during microwave drying. Finally, a rollable blank with a water content of 20%-30% is obtained;

[0067] Drying: the blank is further dried by hot air to a water content of 5%, wherein the drying temperature is 150℃, and the drying time is 8h. Finally, a rollable roll material is obtained.

[0068] The room temperature thermal conductivity of the obtained inorganic composite thermal insulation material is 0.045 W·m -1 K-1 After being kept at 600℃ for 10h, the linear shrinkage is 1.5%. After being soaked in liquid sodium at 400℃ for 8h, the weight gain is less than 10%, only a small amount of sodium adheres to the surface, no sodium penetrates into the interior, and the insulation material has no obvious reaction with sodium.

[0069] Figure 1 The SEM image of the inorganic composite insulation material prepared in Example 1 shows that the ceramic fibers interweave to impart flexibility to the material, and the fibers and particles, especially the fibers, form multi-level pores of hundreds of nanometers and several to tens of microns, and the alumina agglomerates dispersed between the fibers and the particles have nano-level pores of tens to hundreds of nanometers.

[0070] Example 2

[0071] A low-carbon preparation method of an inorganic composite insulation material for high-temperature liquid sodium pipelines, comprising the following steps:

[0072] According to the weight fraction,

[0073] 25 parts of hollow mullite ceramic fibers (diameter 4μm, length 5cm) are weighed; the mullite ceramic fibers are stirred with 2 parts of sodium dodecyl sulfonate and 30 parts of water to obtain a ceramic fiber dispersion liquid;

[0074] After 15 parts of metakaolin and 5 parts of water glass and 3 parts of sodium hydroxide are mixed with 70 parts of water, 40 parts of γ-alumina agglomerate powder are added and mixed and stirred to obtain a ceramic microbead slurry; the particle size of the γ-alumina agglomerate powder is 20μm;

[0075] Finally, the ceramic fiber dispersion liquid and the ceramic microbead slurry are mixed, 5 parts of biotite flakes (diameter 50μm, thickness 3μm) and 5 parts of polyvinyl alcohol are added, and a slurry with a water content of 90% is prepared, and the slurry is uniformly mixed and then left to stand for 10h; thereafter, stirring and standing are repeated three times.

[0076] Casting forming treatment: after the prepared slurry is dehydrated to 50%, it is pumped into the barrel of a casting forming machine, alumina fiber cloth is used as the substrate, and casting forming is performed, the distance between the doctor blade and the substrate is controlled to be 10mm, the pressure of the doctor blade is controlled to be 1MPa, and the casting forming speed is 1.5m / min. During the casting forming process, further dehydration is performed by microwave heating, the microwave frequency is 2.45GHz, the microwave heating power is 60kW, the microwave drying time is 20min, and the vacuum degree is controlled to be 10Pa during the microwave drying process. Finally, a rollable green body with a water content of 20%-30% is obtained;

[0077] Drying: the green body is further dried by hot air to a moisture content of 10%, wherein the drying temperature is 120℃, and the drying time is 6h, and finally a rollable roll material is obtained.

[0078] The room temperature thermal conductivity of the obtained thermal insulation material is 0.040 W·m -1 K -1 After being soaked in liquid sodium at 400℃ for 8h, the weight gain is less than 15%, only a small amount of sodium adheres to the surface, no sodium penetrates into the interior, and the thermal insulation material has no obvious reaction with sodium.

[0079] Comparative Example 1

[0080] The difference from Example 1 is that,

[0081] The hollow alumina ceramic fiber is replaced with glass fiber.

[0082] The room temperature thermal conductivity of the obtained inorganic composite thermal insulation material is 0.046 W·m -1 K -1 The replacement of fibers has no obvious effect on the thermal conductivity, but the weight gain of the inorganic composite thermal insulation material prepared in Comparative Example 1 is more than 80% after being soaked in liquid sodium at 400℃ for 8h, that is, the inorganic composite thermal insulation material has a serious sodium absorption, and there is a lot of sodium on the surface and inside, which has a hidden danger of direct combustion reaction with sodium when exposed to air.

[0083] Comparative Example 2

[0084] The difference from Example 1 is that,

[0085] The γ-alumina powder is replaced with silica aerogel powder.

[0086] The room temperature thermal conductivity of the obtained inorganic composite thermal insulation material is 0.038 W·m -1 K -1 Although the thermal conductivity of the thermal insulation material even slightly decreases due to the replacement of γ-alumina powder with silica aerogel powder, the thermal insulation material can be observed to rapidly react with sodium at 400℃, the reaction front temperature exceeds 820℃, sodium silicate is generated after the reaction, the weight gain is more than 300% after soaking for 8h, and the thermal insulation material is disabled due to the direct reaction with sodium and the full absorption of sodium.

[0087] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements easily thought of by those skilled in the art within the technical range disclosed in the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An inorganic composite heat insulating material for high temperature liquid sodium piping, characterized by using an alumina fiber cloth as a matrix, wherein the inorganic composite heat insulating material is composed of the alumina fiber cloth and a binder, and the binder is composed of a mixture of a sodium silicate binder and a sodium aluminosilicate binder. By weight, it also includes the following ingredients: Hollow ceramic fiber 25-35 parts, γ-alumina powder 30-40 parts, metakaolin 10-15 parts, mica flakes 5-10 parts, water glass 3-5 parts, sodium hydroxide 1-3 parts, polyvinyl alcohol 5 parts, and sodium dodecyl sulfonate 2-3 parts.

2. The inorganic composite thermal insulation material for high-temperature liquid sodium pipes according to claim 1, characterized by, By weight, the following ingredients are included: The composition includes 35 parts hollow ceramic fiber, 30 parts γ-alumina powder, 12 parts metakaolin, 10 parts mica flakes, 3 parts water glass, 2 parts sodium hydroxide, 5 parts polyvinyl alcohol, and 3 parts sodium dodecyl sulfonate.

3. The inorganic composite thermal insulation material for high-temperature liquid sodium pipes according to claim 1, characterized by, By weight, the following ingredients are included: The composition includes 25 parts hollow ceramic fiber, 40 parts γ-alumina powder, 15 parts metakaolin, 5 parts mica flakes, 5 parts water glass, 3 parts sodium hydroxide, 5 parts polyvinyl alcohol, and 2 parts sodium dodecyl sulfonate.

4. The inorganic composite thermal insulation material for high-temperature liquid sodium pipelines according to any one of claims 1-3, characterized in that, The hollow ceramic fiber includes hollow alumina ceramic fiber or hollow mullite ceramic fiber.

5. An inorganic composite thermal insulation material for high-temperature liquid sodium pipelines according to any one of claims 1-3, characterized in that, The mica sheet is biotite or phlogopite.

6. The inorganic composite thermal insulation material for high-temperature liquid sodium pipes according to claim 1, characterized by, The aspect ratio of the hollow ceramic fiber is (2-5)cm∶(1-5)μm; The γ-alumina powder is an aggregate of 20-40 μm; The mica sheet has a diameter of 50-70 μm and a thickness of less than 5 μm.

7. A method for preparing an inorganic composite thermal insulation material for high-temperature liquid sodium pipelines, characterized in that, Includes the following steps: Weigh and mix the raw materials according to the weight proportions of any one of claims 1-6; The inorganic composite thermal insulation material is prepared by combining the mixed raw materials with alumina fiber cloth as the matrix and using casting molding and microwave heating treatment.

8. The preparation method of an inorganic composite thermal insulation material for high-temperature liquid sodium pipelines according to claim 7, characterized in that, The preparation method specifically includes the following steps: Water and sodium dodecyl sulfonate were added to the hollow ceramic fibers to obtain a ceramic fiber dispersion. The metakaolin, water glass, sodium hydroxide, γ-alumina powder and water are mixed and stirred to obtain ceramic microsphere slurry; The ceramic fiber dispersion, ceramic microsphere slurry, mica sheets, polyvinyl alcohol and water are mixed and stirred to prepare a slurry. The slurry was dehydrated to a moisture content of 50%, and then cast and microwave-treated with aluminum oxide fiber cloth as the matrix, followed by drying to obtain the inorganic composite thermal insulation material.

9. The method according to claim 8, wherein the inorganic composite thermal insulation material for high-temperature liquid sodium pipes is prepared by mixing the inorganic binder, the inorganic filler, and the inorganic fiber, and then sintering the mixture at a temperature of 1,000°C to 1,500°C for 1 to 10 hours. The parameter conditions in the casting process are as follows: The distance between the squeegee and the substrate is controlled at 8-12mm, the pressure of the squeegee is controlled at 0.8-1.2MPa, and the casting speed is 1-2m / min.

10. The preparation method of an inorganic composite thermal insulation material for high-temperature liquid sodium pipelines according to claim 8, characterized in that, The parameter conditions for the microwave heating process are as follows: Microwave frequency 2.45GHz, microwave heating power 60kW, microwave drying time 20-25min, vacuum degree 10-20Pa.

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