Furnace lining structure and preparation method thereof

Abstract

The invention discloses a furnace lining structure and a preparation method thereof, and belongs to the technical field of ferrous metallurgy. The furnace lining structure sequentially comprises a furnace wall steel shell, a heat preservation layer, an isolation layer and a working layer from outside to inside, the working layer is made of corundum refractory materials, the heat preservation layer is made of aluminum-silicon refractory materials, and the isolation layer is a nanometer oxide coating. The nano oxide is at least one of nano aluminum oxide and nano zirconium oxide. Stable and reliable operation of equipment related to the hydrogen reduction process is promoted, the service life of refractory materials is prolonged, and safe production is strengthened.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and mainly relates to a furnace lining structure and its preparation method for a direct hydrogen reduction process. Background Technology

[0003] Because the direct reduction process involves relatively low reaction temperatures and is a solid-state reaction without melting, it is not subject to the corrosive effects of molten iron. Therefore, many people do not pay enough attention to the furnace lining refractory materials, believing that ordinary refractory materials are sufficient for production. However, hydrogen gas has high permeability, strong reducing properties, and is flammable and explosive. It easily causes hydrogen embrittlement and corrosion to metallic materials, and can even lead to leaks and safety accidents. Therefore, the direct reduction technology using hydrogen places entirely new demands on the lining refractory materials. In existing vertical shaft furnace direct reduction processes using mixed coal gas as the reducing gas, the furnace lining refractory materials used are mainly alumina-silicon based products, such as mullite and mullite / corundum refractory bricks or castables. The working layer typically uses low-iron high-alumina bricks and corundum hollow sphere castables, while the insulation layer uses feldspar bricks, lightweight mullite bricks, and low-iron insulating castables. Current furnace lining refractory structures face the following problems when used in high-temperature hydrogen environments of 600-950℃: Firstly, hydrogen molecules are small, and especially at high temperatures, hydrogen has strong permeability, easily diffusing into the insulation layer or metal shell through open pores, microcracks, and other defects in the refractory material. Secondly... Hydrogen has extremely strong reducing properties at high temperatures of 600℃-950℃ and high pressures of 0.2-0.8MPa, and can react with some components in refractory materials. In particular, studies have found that hydrogen can react with silicon dioxide at high temperatures. Conventional insulation layers are generally made of silicon-aluminum materials. In addition, there are inevitably some other impurities that can be corroded by hydrogen or water vapor, such as iron oxide. This means that the furnace lining refractory will be gradually corroded in the high-temperature environment of hydrogen, resulting in structural damage, reduced strength, and even refractory detachment. At the same time, hydrogen can also come into contact with the metal shell, causing hydrogen embrittlement and other problems, which increases the risk to production safety.

[0004] Currently, research institutions and enterprises are mainly conducting research on the selection of refractory raw materials and the development of new refractory materials to address the above-mentioned issues. For example, patent (CN202310415306.2) discloses a corundum refractory material for hydrogen metallurgy and its preparation method. The raw materials include 70-85 wt% tabular corundum, 8-15 wt% calcium aluminate cement, 0.5-9 wt% titanium dioxide, and 2-7 wt% alumina micropowder. A water-reducing agent (which is any one or a mixture of two of polyether, polycarboxylic acid, sodium tripolyphosphate, sodium tetrapolyphosphate, and sodium hexametaphosphate, with the water-reducing agent accounting for 0.1% of the raw material mass) is added. 0.8%), mixed evenly to obtain a premix; add water to the premix, stir evenly, cast into molds, cure at room temperature, demold, and dry to obtain corundum preforms, and then keep the corundum preforms at 1600-1800℃ for 3-8 hours under carbon embedding conditions to obtain the final product; Patent (CN202411844100.2) discloses a hydrogen-based vertical furnace resistant Al2O3-Cr2O3 refractory material and its preparation method, comprising the following raw materials in parts by weight: 30-40 parts of chromium corundum particles with a particle size of 4-1mm, and 1-0mm of... The preparation method comprises: 10-15 parts aluminum chromium slag particles, 10-20 parts fused brown corundum particles with a particle size of 3-1 mm, 20-30 parts fused white corundum powder with a particle size of less than 0.074 mm, 5-10 parts alumina micro powder with a particle size of less than 6 μm, 3-5 parts chromium oxide green with a particle size of less than 0.074 mm, 3-4 parts phosphoric acid, and 3-10 parts erbium oxide; characterized by: Step 1, weighing each raw material according to the above-mentioned weight proportions; Step 2, mixing the chromium oxide green with a particle size of less than 0.074 mm and erbium oxide evenly, placing them in a sagger and placing them in a kiln at 1450°C. Firing at 1500℃ for 2 days After 4 hours, the ball mill 2... After 4 hours, the mixture is obtained and ready for use; Step 3: Particle size 4 1mm chromium corundum particles, particle size 1 0mm aluminum chromium slag particles, particle size 3 1mm fused brown corundum particles are added to a sand mixer in the above proportions, and then mixed with phosphoric acid and milled for 1 minute. 2 minutes; Step 4: Combine 6.5g of fused white corundum powder (particle size less than 0.074mm), alumina micro powder (particle size less than 6µm), and the mixture obtained in Step 2. 9.5 parts by weight were placed in a premixer and mixed for 1 minute. 2 minutes to obtain premixed fine powder; Step 5: Add the premixed fine powder obtained in Step 4 to the mixing and grinding equipment in Step 3, and wet grind for 5 minutes. 7 minutes, 22 tadpoles After molding for 26 hours, the Al2O3 material is dried at 200℃ for 24 hours to obtain the hydrogen-based vertical furnace-resistant Al2O3 material resistant to H2 and CO corrosion. Cr2O3 refractory material; Patent (CN202411483755.1) discloses a hydrogen-based furnace erosion-resistant alumina-silicon carbide refractory material and its preparation method, comprising the following raw materials in parts by weight: 30-40 parts of coarse silicon carbide powder with a particle size of 3-1mm, 20-30 parts of fused white corundum with a particle size of less than 1-0mm, 3-10 parts of kyanite with a particle size of less than 0-0.2mm, 10-20 parts of fine silicon carbide powder with a particle size of less than 0.074mm, and a particle size of less than 3μm. The preparation method includes the following steps: (1) Weigh each raw material according to the formula; (2) Place the sodium hexametaphosphate in a beaker, heat it to 200℃ and keep it warm until the sodium hexametaphosphate dissolves into a transparent solution; (3) Place the coarse silicon carbide powder, fused white corundum, and kyanite in a stirring device and stir for 1 minute. 2 minutes; (4) Mix fine silicon carbide powder, alumina powder, graphite, white mud, and solid aluminum dihydrogen phosphate in a premixer for 1 minute. 2 minutes to obtain fine powder; (5) Add the fine powder obtained in step (4) to the stirring device in step (3), add the transparent solution obtained in step (2), and stir for 1 minute. After 3 minutes, the material is left to stand for 48 hours to obtain corrosion-resistant alumina. Silicon carbide refractory materials. While the above technologies disclose some novel refractory material techniques for resisting hydrogen erosion, these methods often require complex raw materials and specific proportions and processing steps, increasing costs. Although the new refractory materials themselves may possess hydrogen resistance, they cannot prevent hydrogen from permeating through the refractory material. Hydrogen can still reach the metal shell side, posing a risk of erosion of the insulation refractory material on the shell side or causing hydrogen embrittlement of the metal, adversely affecting equipment lifespan and production safety. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a furnace lining structure and its preparation method for use in high-temperature hydrogen environments, so as to promote the stable and reliable operation of equipment related to hydrogen reduction processes, extend the service life of refractory materials, and enhance safe production.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A furnace lining structure comprises, from the outside to the inside, a furnace wall steel shell, an insulation layer, an isolation layer, and a working layer. The working layer is made of corundum refractory material, the insulation layer is made of aluminosilicate refractory material, and the isolation layer is a nano-oxide coating.

[0008] Furthermore, the thickness of the insulation layer is 100-350mm, the thickness of the isolation layer is 0.01-0.1mm, and the thickness of the working layer is 50-300mm.

[0009] Furthermore, the working layer contains Al2O3 with a mass content ≥96%, SiO2 and Fe2O3 with a total mass content ≤0.5%, and K2O and Na2O with a total mass content ≤0.3%; the apparent porosity of the working layer is ≤10%; by controlling the components that can react with hydrogen, such as SiO2, Fe2O3, K2O, and Na2O, as well as their porosity, the resistance to hydrogen reaction and hydrogen permeation is enhanced.

[0010] The insulation layer contains ≥60% Al2O3, ≤30% SiO2, ≤0.5% Fe2O3, and ≤0.5% total K2O and Na2O; the apparent porosity of the insulation layer is ≥50%; the impurity content is controlled and the Al2O3 content is increased to improve strength and make it similar to the expansion performance of the working layer.

[0011] The nano-oxide is at least one of nano-alumina and nano-zirconia.

[0012] Furthermore, the furnace lining structure is also provided with anchors, one end of which is welded and fixed to the inner side of the furnace wall steel shell, and the other end extends into the insulation layer and the working layer.

[0013] Furthermore, the anchor is a V-shaped or Y-shaped anchor.

[0014] Furthermore, the number of anchors is several, and the material of the anchors is stainless steel.

[0015] The method for preparing the above-mentioned furnace lining structure includes the following steps: (1) After cleaning the inner wall of the furnace steel shell, the aluminum-silicon refractory casting material is constructed on the inner wall of the furnace shell according to the design thickness of the insulation layer using the formwork casting method. After casting and molding, it is cured and heat-treated to form the insulation layer. (2) The insulation layer prepared in step (1) is coated by brushing or spraying, and the coating layer formed on the surface of the insulation layer using nano-oxide sol is cured and heat-treated to form an isolation layer; (3) According to the design thickness of the working layer of the furnace lining, the formwork casting method is adopted. On the basis of the isolation layer made in step (2), the corundum refractory casting material is constructed. After casting and molding, it is cured and heat-treated according to the specifications to form the working layer and obtain the furnace lining structure.

[0016] Furthermore, in step (1), when using anchors, after cleaning the inner wall of the furnace shell, mark the anchoring points according to the design requirements and weld the anchors, apply asphalt paint or wrap refractory fiber paper to the anchors to reserve thermal expansion gaps, and then prepare the insulation layer.

[0017] Furthermore, in step (1), after casting and molding, the surface is left to stand for at least 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 24-48 hours. The temperature is increased from room temperature to 110-120℃ at 10-15℃ / h and kept at that temperature for 15-48 hours. The temperature is then increased to 150-160℃ and kept at that temperature for 15-48 hours. After that, the temperature is increased to 350-360℃ and kept at that temperature for 15-48 hours before naturally cooling to form an insulation layer.

[0018] Furthermore, in step (2), the nano-oxide sol is at least one of nano-alumina sol and nano-zirconia sol, and the solid content of the nano-oxide sol is ≥25%.

[0019] Furthermore, in step (2), after the coating layer has cured naturally for 2-3 hours, it is heated to 110-120℃ at 2-3℃ / min and kept at that temperature for 2-3 hours, then heated to 350-360℃ and kept at that temperature for 2-3 hours before being naturally cooled to form an isolation layer.

[0020] Furthermore, in step (3), after casting and molding, the surface is left to stand for at least 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 24-48 hours. The temperature is then increased from room temperature to 110-120℃ at 10-15℃ / h and kept at that temperature for 15-48 hours. The temperature is then increased to 150-160℃ and kept at that temperature for 15-48 hours. The temperature is then increased to 350-360℃ and kept at that temperature for 15-48 hours. The temperature is then increased to 600-610℃ at 15-20℃ / h and kept at that temperature for 10-15 hours. The temperature is then increased to 950-1000℃ at 25-30℃ / h and kept at that temperature for 24-36 hours. After that, the surface is allowed to cool naturally to form an insulation layer.

[0021] Furthermore, in step (3), alumina fibers accounting for no more than 1% of the volume fraction of the castable can be added during the construction of the working layer castable, wherein the mass content of Al2O3 in the alumina fibers is ≥99%.

[0022] Due to the extremely strong permeability and reducing properties of hydrogen, existing conventional furnace lining refractory structures and materials face significant challenges in high-temperature hydrogen environments. This invention proposes a furnace lining structure and preparation method, employing a multi-layered composite structure consisting of an insulation layer, an isolation layer, and a working layer. The corundum working layer is in direct contact with the materials and atmosphere within the reactor. Its main component, alumina, is highly stable in both hydrogen and water vapor, exhibiting excellent mechanical strength and wear resistance after heat treatment and firing. The aluminosilicate insulation layer is lightweight, high-strength, and provides excellent thermal insulation, effectively reducing heat loss. By optimizing the material composition of the working layer and insulation layer, their resistance to hydrogen erosion is improved. Based on the above structure, a nano-oxide isolation layer is added between the insulation layer and the working layer. The coating layer, which is formed by nano-oxide sol-gel and heat treatment, has a grain size at the nanoscale and fills the pores on the refractory surface. The porosity of the isolation layer is close to zero, which is significantly lower than that of the working layer and the insulation layer. The densely packed nanostructure can effectively block the passage of hydrogen and greatly reduce hydrogen permeation, thereby mitigating or avoiding the erosion of the insulation layer refractory and the hydrogen embrittlement of the furnace wall metal by hydrogen. The above composite furnace lining structure plays a positive role in extending equipment life and production safety.

[0023] Beneficial effects: This invention provides a composite furnace lining structure and its preparation method, which can be used in direct hydrogen reduction processes. The furnace lining structure of this invention organically combines the advantages of corundum working layer in terms of high temperature and pressure resistance, hydrogen resistance, and material wear resistance with the heat insulation and energy-saving advantages of insulation layer. At the same time, the addition of an isolation layer enhances the function of isolating hydrogen, reducing or avoiding the erosion of the insulation layer refractory material or the hydrogen embrittlement effect on the furnace shell metal caused by hydrogen penetration into the furnace lining. This plays a positive role in extending equipment life and production safety. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the furnace lining structure; In the diagram: 1. Furnace wall steel shell, 2. Insulation layer, 3. Isolation layer, 4. Working layer, 5. V-shaped anchor, 6. V-shaped anchor. Detailed Implementation

[0025] The following description is based on specific embodiments: Example 1 like Figure 1 As shown, a furnace lining structure comprises, from the outside to the inside, a furnace wall steel shell 1, an insulation layer 2, an isolation layer 3, and a working layer 4, wherein the thickness of the insulation layer is 250 mm, the thickness of the isolation layer is 0.01-0.1 mm, and the thickness of the working layer is 300 mm.

[0026] The furnace lining structure is also equipped with several V-shaped anchors 5 and Y-shaped anchors 6. The anchors are made of 316L stainless steel and are arranged alternately with a spacing of 200mm. One end of the anchor is welded and fixed to the inner side of the furnace wall steel shell, and the other end extends into the insulation layer and working layer.

[0027] The working layer is made of corundum castable. The final working layer has an Al2O3 mass content of 96.20%, a total SiO2 and Fe2O3 mass content of 0.49%, a total K2O and Na2O mass content of 0.30%, and an apparent porosity of 10%.

[0028] The insulation layer is made of lightweight aluminum-silicon castable. The final insulation layer has an Al2O3 mass content of 62.15%, a SiO2 mass content of 29.80%, a Fe2O3 mass content of 0.45%, a total K2O and Na2O mass content of 0.48%, and an apparent porosity of 55%.

[0029] The isolation layer is made of nano-oxide sol, using nano-alumina sol, and the solid content of the nano-oxide sol is 25.65%.

[0030] The above-mentioned method for preparing the furnace lining structure mainly includes the following steps: (1) After cleaning the inner wall of the furnace steel shell, remove rust, oil stains, etc. Mark the anchoring points according to the design requirements and weld the anchors. Apply asphalt paint to the anchors to leave a thermal expansion gap.

[0031] (2) The furnace lining insulation layer is designed with formwork and cast. The aluminum-silicon refractory castable is constructed on the inner wall of the furnace shell. After casting, it is left to stand for 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 48 hours. The temperature is increased from room temperature to 110℃ at 10℃ / h and kept for 24 hours. The temperature is then increased to 150℃ and kept for 24 hours. After that, the temperature is increased to 350℃ at 10℃ / h and kept for 24 hours. Then it is naturally cooled to room temperature to form the insulation layer.

[0032] (3) The surface of the insulation layer prepared in step (2) is coated by brushing with nano-oxide sol to form a coating layer. After natural curing for 2 hours, the temperature is raised to 120℃ at 2℃ / min and kept for 2 hours. Then the temperature is raised to 350℃ and kept for 3 hours. After natural cooling to room temperature, the isolation layer is formed.

[0033] (4) Based on the design thickness of the working layer of the furnace lining, a formwork casting method is adopted. On the basis of the isolation layer made in step (3), corundum refractory castable is constructed. After casting, it is left to stand for 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 48 hours. The temperature is increased from room temperature to 110℃ at 15℃ / h and held for 24 hours. The temperature is then increased to 150℃ and held for 24 hours. The temperature is increased to 350℃ at 15℃ / h and held for 24 hours. The temperature is increased to 600℃ at 15℃ / h and held for 12 hours. The temperature is increased to 950℃ at 30℃ / h and held for 24 hours. After that, it is naturally cooled to room temperature to form the working layer and obtain the furnace lining structure. When constructing the working layer castable, 1% of alumina fiber by volume of the working layer castable can be added. The alumina fiber has an Al2O3 mass content of 99.5%.

[0034] Example 2 like Figure 1 As shown, a furnace lining structure comprises, from the outside to the inside, a furnace wall steel shell, an insulation layer, an isolation layer, and a working layer, wherein the thickness of the insulation layer is 100 mm, the thickness of the isolation layer is 0.01-0.1 mm, and the thickness of the working layer is 60 mm.

[0035] The furnace lining structure is also equipped with several V-shaped anchors 5 and Y-shaped anchors 6. The anchors are made of 316L stainless steel and are arranged in an alternating pattern with a spacing of 100mm. One end of the anchor is welded and fixed to the inner side of the furnace wall steel shell, and the other end extends into the insulation layer and working layer.

[0036] The working layer is made of corundum castable, and the final working layer has an Al2O3 mass content of 96.50%, a total SiO2 and Fe2O3 mass content of 0.45%, a total K2O and Na2O mass content of 0.28%, and an apparent porosity of 9.5%.

[0037] The insulation layer is made of lightweight aluminum-silicon castable. The final insulation layer contains 63.50% Al2O3, 28.50% SiO2, 0.50% Fe2O3, and 0.45% K2O and Na2O. The apparent porosity of the insulation layer is 53%.

[0038] The isolation layer is made of nano-oxide sol, using nano-zirconia sol, and the solid content of the nano-oxide sol is 27%.

[0039] The above-mentioned method for preparing the furnace lining structure mainly includes the following steps: (1) After cleaning the inner wall of the furnace steel shell, remove rust, oil stains, etc. Mark the anchoring points according to the design requirements and weld the anchors. Wrap the anchors with refractory fiber paper for surface treatment to reserve thermal expansion gap.

[0040] (2) The furnace lining insulation layer is designed with formwork and cast. The aluminum-silicon refractory castable is constructed on the inner wall of the furnace shell. After casting, it is left to stand for 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 24 hours. The temperature is increased from room temperature to 110℃ at 10℃ / h and kept for 16 hours. The temperature is then increased to 150℃ and kept for 16 hours. After that, the temperature is increased to 350℃ at 10℃ / h and kept for 16 hours. Then it is naturally cooled to room temperature to form the insulation layer.

[0041] (3) The surface of the insulation layer prepared in step (2) is coated by spraying with nano-oxide sol to form a coating layer. After natural curing for 2 hours, the temperature is raised to 120℃ at 2℃ / min and kept for 2 hours. Then the temperature is raised to 350℃ and kept for 3 hours. After natural cooling to room temperature, the isolation layer is formed.

[0042] (4) According to the design thickness of the working layer of the furnace lining, the corundum refractory castable is constructed on the basis of the isolation layer made in step (3). After casting, it is left to stand for 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 24 hours. The temperature is increased from room temperature to 110℃ at 15℃ / h and kept for 16 hours. The temperature is increased to 150℃ and kept for 16 hours. The temperature is increased to 350℃ at 15℃ / h and kept for 16 hours. The temperature is increased to 600℃ at 15℃ / h and kept for 12 hours. The temperature is increased to 950℃ at 30℃ / h and kept for 24 hours. After that, it is naturally cooled to room temperature to form the working layer and obtain the furnace lining structure.

[0043] Example 3 like Figure 1 As shown, a furnace lining structure comprises, from the outside to the inside, a furnace wall steel shell, an insulation layer, an isolation layer, and a working layer, wherein the thickness of the insulation layer is 350 mm, the thickness of the isolation layer is 0.01-0.1 mm, and the thickness of the working layer is 200 mm.

[0044] The furnace lining structure is also equipped with several V-shaped anchors 5 and Y-shaped anchors 6. The anchors are made of 316L stainless steel and are arranged in an alternating pattern with a spacing of 150mm. One end of the anchor is welded and fixed to the inner side of the furnace wall steel shell, and the other end extends into the insulation layer and working layer.

[0045] The working layer is made of corundum castable, and the final working layer has an Al2O3 mass content of 98.50%, a total SiO2 and Fe2O3 mass content of 0.35%, a total K2O and Na2O mass content of 0.20%, and an apparent porosity of 9.35%.

[0046] The insulation layer is made of lightweight aluminum-silicon castable. The final insulation layer contains 63.50% Al2O3, 29.50% SiO2, 0.40% Fe2O3, and 0.42% K2O and Na2O. The apparent porosity of the insulation layer is 56%.

[0047] The isolation layer is made of nano-oxide sol, using nano-alumina sol, and the solid content of the nano-oxide sol is 30%.

[0048] The above-mentioned method for preparing the furnace lining structure mainly includes the following steps: (1) After cleaning the inner wall of the furnace steel shell, remove rust, oil stains, etc. Mark the anchoring points according to the design requirements and weld the anchors. Apply asphalt paint to the anchors to leave a thermal expansion gap.

[0049] (2) According to the design thickness of the furnace lining insulation layer, formwork is used for casting. Aluminosilicate refractory castable is constructed on the inner wall of the furnace shell. After casting, it is left to stand for 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 48 hours. The temperature is increased from room temperature to 110℃ at 10℃ / h and kept for 36 hours. The temperature is then increased to 150℃ and kept for 24 hours. After that, the temperature is increased to 350℃ at 10℃ / h and kept for 24 hours. Then it is naturally cooled to room temperature to form the insulation layer.

[0050] (3) The surface of the insulation layer prepared in step (2) is coated by brushing with nano-oxide sol to form a coating layer. After natural curing for 2 hours, the temperature is raised to 120℃ at 2℃ / min and kept for 2 hours. Then the temperature is raised to 350℃ and kept for 3 hours. After natural cooling to room temperature, the isolation layer is formed.

[0051] (4) According to the design thickness of the working layer of the furnace lining, the corundum refractory castable is constructed on the basis of the isolation layer made in step (3). After casting, it is left to stand for 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 48 hours. The temperature is increased from room temperature to 110℃ at 15℃ / h and kept for 24 hours. The temperature is then increased to 150℃ and kept for 24 hours. The temperature is increased to 350℃ at 15℃ / h and kept for 24 hours. The temperature is increased to 600℃ at 15℃ / h and kept for 12 hours. The temperature is increased to 950℃ at 30℃ / h and kept for 24 hours. After that, it is naturally cooled to room temperature to form the working layer and obtain the furnace lining structure.

Claims

1. A furnace lining structure, characterized in that, From the outside in, the structure consists of a furnace wall steel shell, an insulation layer, an isolation layer, and a working layer. The working layer is made of corundum refractory material, the insulation layer is made of aluminosilicate refractory material, and the isolation layer is a nano-oxide coating.

2. The furnace lining structure according to claim 1, characterized in that, The thickness of the insulation layer is 100-350mm, the thickness of the isolation layer is 0.01-0.1mm, and the thickness of the working layer is 50-300mm.

3. The furnace lining structure according to claim 1, characterized in that, The working layer contains ≥96% Al2O3 by mass, ≤0.5% total SiO2 and Fe2O3 by mass, and ≤0.3% total K2O and Na2O by mass; the apparent porosity of the working layer is ≤10%. The insulation layer contains ≥60% Al2O3, ≤30% SiO2, ≤0.5% Fe2O3, and ≤0.5% total K2O and Na2O; the apparent porosity of the insulation layer is ≥50%. The nano-oxide is at least one of nano-alumina and nano-zirconia.

4. The furnace lining structure according to claim 1, characterized in that, The furnace lining structure is also equipped with anchors, one end of which is fixed to the inside of the furnace wall steel shell, and the other end extends into the insulation layer and the working layer.

5. The furnace lining structure according to claim 4, characterized in that, The anchor is a V-shaped or Y-shaped anchor; there are several anchors, and the material of the anchor is stainless steel.

6. The method for preparing the furnace lining structure according to any one of claims 1-5, characterized in that, It includes the following steps: (1) After cleaning the inner wall of the furnace steel shell, the aluminum-silicon refractory casting material is constructed on the inner wall of the furnace shell according to the thickness of the insulation layer by formwork casting. After casting and molding, it is cured and heat-treated to form the insulation layer. (2) The surface of the insulation layer prepared in step (1) is coated by brushing or spraying with nano-oxide sol to form a coating layer on the surface of the insulation layer, and then cured and heat-treated to form an isolation layer. (3) According to the thickness of the working layer of the furnace lining, the formwork casting method is adopted. On the basis of the isolation layer made in step (2), the corundum refractory casting material is constructed. After casting and molding, it is cured and heat-treated to form the working layer and obtain the furnace lining structure.

7. The preparation method according to claim 6, characterized in that, In step (1), when using anchors, after cleaning the inner wall of the furnace shell, mark the anchoring points and fix the anchors, apply asphalt paint or wrap refractory fiber paper to the anchors for surface treatment, and then prepare the insulation layer.

8. The preparation method according to claim 6, characterized in that, In step (2), the solid content of the nano-oxide sol is ≥25%.

9. The preparation method according to claim 6, characterized in that, In step (1), after casting and molding, the surface is left to stand for at least 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 24-48 hours. The temperature is then increased from room temperature to 110-120℃ at a rate of 10-15℃ / h and held for 15-48 hours. The temperature is then increased to 150-160℃ and held for 15-48 hours. After that, the temperature is increased to 350-360℃ and held for 15-48 hours before being allowed to cool naturally to form an insulation layer. In step (2), after the coating layer has cured naturally for 2-3 hours, it is heated to 110-120℃ at 2-3℃ / min and kept at that temperature for 2-3 hours, then heated to 350-360℃ and kept at that temperature for 2-3 hours before being cooled naturally to form an isolation layer. In step (3), after casting and molding, the surface is left to stand for at least 24 hours before demolding. The surface is covered with plastic film and cured at room temperature for 24-48 hours. The temperature is then increased from room temperature to 110-120℃ at a rate of 10-15℃ / h and held for 15-48 hours. The temperature is then increased to 150-160℃ and held for 15-48 hours. The temperature is then increased to 350-360℃ and held for 15-48 hours. The temperature is then increased to 600-610℃ at a rate of 15-20℃ / h and held for 10-15 hours. The temperature is then increased to 950-1000℃ at a rate of 25-30℃ / h and held for 24-36 hours. After that, the surface is allowed to cool naturally to form the working layer.

10. The preparation method according to claim 6, characterized in that, In step (3), when constructing the working layer castable, alumina fibers accounting for no more than 1% of the volume fraction of the working layer castable are added, and the mass content of Al2O3 in the alumina fibers is ≥99%.

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