High-temperature-resistant thermal insulation layer of cracking furnace and preparation process thereof

Abstract

The invention relates to the technical field, and discloses a high-temperature-resistant thermal insulation layer of a cracking furnace and a preparation process of the high-temperature-resistant thermal insulation layer. The thermal insulation layer is prepared from the following raw materials in parts by weight: 50-80 parts of aluminum silicate fiber, 10-25 parts of stabilized zirconia powder, 5-15 parts of activated alumina powder, 1-5 parts of rare earth oxide, 3-10 parts of chopped silicon carbide fiber, 2-8 parts of a composite sintering aid and 1-4 parts of hexagonal boron nitride powder. According to the present invention, the high temperature behavior of the material system is improved, and the embodiment shows that the heating permanent linear change of the prepared thermal insulation layer is controlled between-0.20% and + 0.08% after the 1250 DEG C * 24 h test, and the shrinkage rate of the comparative conventional material reaches-2.3%, such that the significant progress in the high temperature shrinkage reduction aspect is displayed.

Description

Technical Field

[0001] This invention relates to the field of high-temperature industrial furnace technology, and more specifically to a high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process. Background Technology

[0002] Cracking furnaces are core equipment for olefin production in petrochemicals. The temperature of the furnace chamber in the radiant section is maintained above 1100℃ for a long time, and can even reach 1300℃. The performance of the furnace body insulation layer is directly related to energy consumption, operational safety and equipment life.

[0003] Currently, the insulation material commonly used in pyrolysis furnaces is mainly aluminosilicate ceramic fiber products. Although this type of material has good initial thermal insulation performance, it has inherent defects under long-term ultra-high temperature and thermal shock conditions. For example, according to industry tests and comparative verification of this invention, after 24 hours at 1250℃, the permanent linear change rate of conventional high-purity aluminosilicate fiber modules can reach -2.3% to -4.0%, accompanied by severe surface pulverization and strength decay. This significant high-temperature shrinkage will cause gaps in the insulation layer and form thermal bridges, which not only causes the furnace outer wall temperature to exceed the standard (>60℃) and increases energy consumption by 5%-15%, but also poses safety hazards. Although some studies have attempted to add zirconium oxide for improvement, under the specific reducing and cyclic thermal stress environment of the pyrolysis furnace, the effect of single modification is limited and has failed to fundamentally solve the problem of long-term service. Therefore, there is an urgent need for a high-temperature resistant insulation layer for pyrolysis furnaces and its preparation process to solve the aforementioned technical problems. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a high-temperature resistant insulation layer for pyrolysis furnace and its preparation process, so as to solve the problems existing in the background art.

[0005] To achieve the above objectives, the present invention provides a high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process.

[0006] In a first aspect, the present invention provides a high-temperature resistant insulation layer for a pyrolysis furnace, which adopts the following scheme: A high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process, comprising an insulation layer made of the following raw materials in parts by weight: 50-80 parts of aluminosilicate fiber, 10-25 parts of stabilized zirconium oxide powder, 5-15 parts of activated alumina powder, 1-5 parts of rare earth oxides, 3-10 parts of chopped silicon carbide fiber, 2-8 parts of composite sintering aid, and 1-4 parts of hexagonal boron nitride powder. The preparation method of the composite sintering aid includes: mixing silica sol and aluminum sol at a mass ratio of 1:(0.5-2), stirring at 40-60℃ for 0.5-1.5h, then adding zinc borate equivalent to 5%-15% of the total mass of the mixture, and continuing to stir for 2-4h to obtain the final product.

[0007] Preferably, the stabilized zirconium oxide powder is yttrium-stabilized zirconium oxide or calcium-stabilized zirconium oxide, and its median particle size is 1-5 μm; the median particle size of the activated alumina powder is 0.5-3 μm.

[0008] Preferably, the rare earth oxide is at least one of yttrium oxide, cerium oxide, and lanthanum oxide; the length of the chopped silicon carbide fiber is 0.1-2 mm, and the diameter of its single filament is 5-15 μm.

[0009] Preferably, the aluminum silicate fiber has an Al2O3 content of ≥62% and a fiber length of 3-20 mm; the hexagonal boron nitride powder has a median particle size of 0.1-1 μm.

[0010] Preferably, the insulation layer is an integral prefabricated component made by high-temperature sintering, with a bulk density of 350-480 kg / m³. The increase in bulk density is mainly achieved by adding high-density fillers such as stabilized zirconia powder and activated alumina powder, as well as the molding step in the preparation process.

[0011] Preferably, the thermal insulation layer is tested according to GB / T5988-2022 "Test Method for Permanent Linear Change of Refractory Materials under Heating", and the absolute value of the permanent linear change under heating at 1250℃×24h is not greater than 0.25%.

[0012] Secondly, the present invention provides a process for preparing a high-temperature resistant insulation layer for a pyrolysis furnace, using the following scheme: A process for preparing a high-temperature resistant insulation layer for a pyrolysis furnace includes the following steps: S1. Aluminosilicate fibers and chopped silicon carbide fibers are subjected to an opening and dispersion pretreatment; S2. The stabilized zirconium oxide powder, activated alumina powder, rare earth oxide, hexagonal boron nitride powder and the composite sintering aid are mixed and ball-milled to obtain a uniform mixed powder. S3. Dry mix the fiber pretreated in S1 with the mixed powder obtained in S2; S4. Add the molding binder to the mixture from S3 and perform vacuum stirring to produce... A uniform plastic slurry; the molding binder is silica sol or aluminum sol, and its addition amount is 15%-20% of the total mass of the mixture, and the specific amount is adjusted according to the rheological properties of the required slurry; S5. The slurry is injected into a mold and formed into a wet blank by vacuum filtration; S6. The wet blank is subjected to molding or cold isostatic pressing at a pressure of 10-30 MPa; S7. Perform segmented drying on the shaped blank; S8. The dried green body is subjected to staged high-temperature sintering: first, the temperature is increased to 400-500℃ at 1-3℃ / min and held at that temperature, then the temperature is increased to 900-1000℃ at 2-5℃ / min and held at that temperature, and finally the temperature is increased to 1250-1380℃ at 3-8℃ / min and held at that temperature for 4-8 hours. The holding time of the final stage is determined according to the thickness of the green body, and it is cooled with the furnace.

[0013] Preferably, the final stage temperature of the staged high-temperature sintering is 1280-1350℃; the holding time of the final stage is estimated to be 1.0-1.5h per 10mm of green body thickness.

[0014] The technical effects and advantages of this invention are as follows: 1. This invention improves the high-temperature behavior of the material system by introducing rare earth oxides and composite sintering aids. Examples show that the prepared insulation layer, after testing at 1250℃ for 24 hours, exhibits a permanent linear change controlled between -0.20% and +0.08%, while the shrinkage rate of the conventional material in the comparison reaches -2.3%, demonstrating the significant progress of this application in reducing high-temperature shrinkage.

[0015] 2. The present invention, through the combination of short-cut silicon carbide fibers, zirconium oxide and hexagonal boron nitride in the material, helps to improve the thermal shock resistance. The sample of the example can withstand more than 10 cycles in the water quenching thermal shock test at 1100℃. At the same time, the compressive strength of the product at room temperature reaches 1.8-3.2 MPa, which is higher than the strength of the comparative example after traditional material treatment.

[0016] 3. This invention provides basic thermal insulation performance by using aluminum silicate fiber as the matrix. By adjusting the formula and molding process, the bulk density of the preform is controlled at 350-480, which improves the strength of the blank while taking into account the thermal insulation requirements. Attached Figure Description

[0017] Figure 1 This is a process flow diagram for preparing the high-temperature resistant insulation layer of the pyrolysis furnace of the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The high-temperature resistant insulation layer for pyrolysis furnace and its preparation process involved in the present invention are not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Reference Figure 1The present invention provides a high-temperature resistant insulation layer for a pyrolysis furnace, comprising an insulation layer made of the following raw materials in parts by weight: 50-80 parts of aluminosilicate fiber, 10-25 parts of stabilized zirconium oxide powder, 5-15 parts of activated alumina powder, 1-5 parts of rare earth oxides, 3-10 parts of chopped silicon carbide fiber, 2-8 parts of composite sintering aid, and 1-4 parts of hexagonal boron nitride powder. The preparation method of the composite sintering aid includes: mixing silica sol and alumina sol at a mass ratio of 1:(0.5-2), stirring at 40-60℃ for 0.5-1.5h, then adding zinc borate equivalent to 5%-15% of the total mass of the mixture, and continuing to stir for 2-4h to obtain the final product; The stabilized zirconia powder is yttrium-stabilized zirconia or calcium-stabilized zirconia, with a median particle size of 1-5 μm; the median particle size of the activated alumina powder is 0.5-3 μm.

[0020] The rare earth oxide is at least one of yttrium oxide, cerium oxide, and lanthanum oxide; the length of the chopped silicon carbide fiber is 0.1-2 mm, and the diameter of its single filament is 5-15 μm.

[0021] The aluminum silicate fiber contains ≥62% Al2O3 by mass and has a fiber length of 3-20 mm; the median particle size of the hexagonal boron nitride powder is 0.1-1 μm.

[0022] The insulation layer is an integral prefabricated component made by high-temperature sintering, with a bulk density of 350-480 kg / m³. The increase in bulk density is mainly achieved by adding high-density fillers such as stabilized zirconia powder and activated alumina powder, as well as the molding step in the preparation process.

[0023] According to GB / T5988-2022 "Test Method for Permanent Linear Change of Refractory Materials under Heating", the absolute value of the permanent linear change of the insulation layer under heating at 1250℃ for 24h is not greater than 0.25%.

[0024] In the embodiments of this application, the median particle size of both stabilized zirconium oxide powder and activated alumina powder refers to the particle size value corresponding to the cumulative distribution of the volume reference measured by a laser diffraction particle size analyzer when it reaches 50%. It should be noted that the raw materials used in the embodiments of this application, unless otherwise specified, are all commercially available industrial-grade or chemically pure products that can be obtained through conventional commercial channels.

[0025] Reference Figure 1 This invention provides a process for preparing a high-temperature resistant insulation layer for a pyrolysis furnace, comprising the following steps: S1. Aluminosilicate fibers and chopped silicon carbide fibers are subjected to an opening and dispersion pretreatment; S2. Stabilized zirconium oxide powder, activated alumina powder, rare earth oxide, hexagonal boron nitride powder and composite sintering aid are mixed and ball-milled to obtain a uniform mixed powder. S3. Dry mix the fiber pretreated in S1 with the mixed powder obtained in S2; S4. Add a molding binder to the mixture in S3 and perform vacuum stirring to prepare a uniform plastic slurry; the molding binder is silica sol or aluminum sol, and its addition amount is 15%-20% of the total mass of the mixture. The specific amount is adjusted according to the rheological properties of the required slurry. S5. Inject the slurry into the mold and form a wet blank by vacuum filtration; S6. Perform molding or cold isostatic pressing on the wet blank, with a pressure of 10-30MPa; S7. Perform segmented drying on the shaped blank; S8. The dried green body is subjected to staged high-temperature sintering: first, the temperature is increased to 400-500℃ at 1-3℃ / min and held, then the temperature is increased to 900-1000℃ at 2-5℃ / min and held, and finally the temperature is increased to 1250-1380℃ at 3-8℃ / min and held for 4-8 hours. The holding time of the final stage is determined according to the thickness of the green body, and it is cooled with the furnace.

[0026] In this embodiment, the final stage temperature of the staged high-temperature sintering is 1280-1350℃; the holding time of the final stage is estimated to be 1.0-1.5h for every 10mm of green body thickness.

[0027] In the following examples and comparative examples, the key performance tests were all performed in accordance with national standards: permanent linear change upon heating was determined according to GB / T5988-2022; bulk density was determined according to GB / T2997-2015.

[0028] Example 1 Raw material ratio (by weight): Aluminosilicate fiber (Al2O3 content: 65%, fiber length: 5mm): 65 parts; Yttrium-stabilized zirconia powder (median particle size 2 μm): 18 parts; Activated alumina powder (median particle size 1μm): 10 parts; Yttrium oxide (purity > 99%): 3 parts; Short-cut silicon carbide fibers (0.5 mm in length, 10 μm in diameter): 5 parts; Composite sintering aid: 5 parts (prepared by mixing silica sol and aluminum sol in a 1:1 ratio and adding 10% zinc borate), wherein the preparation method is carried out in accordance with claim 1; Hexagonal boron nitride powder (median particle size 0.5 μm): 2 parts.

[0029] Preparation process: S1. Fiber pretreatment: 65 parts of aluminosilicate fiber and 5 parts of chopped silicon carbide fiber are put into an opening machine for opening and dispersion treatment for 5 minutes until the fiber clumps are completely broken up. S2. Powder mixing and ball milling: 18 parts of yttrium-stabilized zirconia powder, 10 parts of activated alumina powder, 3 parts of yttrium oxide, 2 parts of hexagonal boron nitride powder and 5 parts of composite sintering aid were added to a planetary ball mill. Zirconia balls were used as the grinding medium, the ball-to-material ratio was 3:1, the speed was 300 rpm, and the ball milling was carried out for 3 hours to obtain a uniform mixed powder. S3. Dry mixing: Add the fiber pretreated in S1 and all the mixed powder obtained in S2 into a high-speed mixer and dry mix at 1500 rpm for 20 minutes to obtain a mixture in which the fiber and powder are evenly dispersed. S4. Preparation of slurry: Add 20 parts of silica sol (30% solid content) to the mixture in S3 as a molding binder, put it into a vacuum mixer, and stir for 15 minutes under a vacuum of -0.08MPa to make a uniform, bubble-free plastic slurry. S5. Vacuum filtration molding: Inject the slurry into a rectangular mold with dimensions of 200mm×200mm×20mm, turn on the vacuum system (vacuum degree -0.09MPa), and filter for 5 minutes to form a wet blank; S6. Compression molding: The wet blank along with the mold is transferred to a cold isostatic press and molded at a pressure of 20MPa for 3 minutes; S7. Segmented drying: Place the formed green body in a forced-air drying oven and dry at 80℃ for 12 hours, then raise the temperature to 100℃ and dry for 24 hours until the moisture content of the green body is less than 1%; S8. Staged high-temperature sintering: Place the dried green body into a high-temperature sintering furnace and sinter according to the following procedure: raise the temperature from room temperature to 500℃ at a rate of 2℃ / min and hold for 1 hour; then raise the temperature to 950℃ at a rate of 4℃ / min and hold for 2 hours; finally raise the temperature to 1320℃ (final stage) at a rate of 5℃ / min and hold for 6 hours (calculated based on a green body thickness of 20mm, with 1.5h corresponding to every 10mm). After sintering, allow the green body to cool naturally to room temperature in the furnace.

[0030] Example 2 Raw material ratio (by weight): Aluminosilicate fiber (with Al2O3 content ≥62%, fiber length 3-20mm): 80 parts; Yttrium-stabilized zirconia powder (median particle size 1-5 μm): 10 parts; Activated alumina powder (median particle size 0.5-3μm): 5 parts; Yttrium oxide (purity ≥ 99%) 1 part; Short-cut silicon carbide fibers (length 0.1-2 mm, monofilament diameter 5-15 μm): 3 parts; Composite sintering aid: 2 parts (prepared by mixing silica sol and aluminum sol in a 1:1 ratio and adding 10% zinc borate), wherein the preparation method is carried out in accordance with claim 1; Hexagonal boron nitride powder (median particle size 0.1-1μm): 1 part.

[0031] Preparation process: S1. Put 80 parts of aluminosilicate fiber and 3 parts of chopped silicon carbide fiber into an opening machine for opening and dispersion treatment for 5 minutes until the fiber clumps are completely fluffy and free of lumps.

[0032] S2. Add 10 parts of calcium-stabilized zirconia powder, 5 parts of activated alumina powder, 1 part of cerium oxide, 1 part of hexagonal boron nitride powder and 2 parts of composite sintering aid into a planetary ball mill, use zirconia balls as the grinding medium, the ball-to-material ratio is 2.5:1, the rotation speed is 250 rpm, and the ball milling process is carried out for 2.5 hours to obtain a uniform mixed powder. S3. Add the fiber pretreated in S1 and all the mixed powder obtained in S2 into a high-speed mixer and dry mix at 1200 rpm for 15 minutes to obtain a mixture in which the fiber and powder are macroscopically uniformly dispersed. S4. Add 18 parts of aluminum sol to the mixture in S3 as a molding binder, put it into a vacuum mixer, and stir for 10 minutes under a vacuum of -0.07MPa to make a uniform, bubble-free plastic slurry. S5. Pour the slurry into a rectangular mold with dimensions of 150mm×150mm×15mm, turn on the vacuum system, and filter for 4 minutes to form a wet blank; S6. Transfer the wet blank along with the mold to a cold isostatic press and press it at a pressure of 15 MPa for 2 minutes to form the blank. S7. Place the formed blank in a forced-air drying oven and dry at 60℃ for 10 hours, then raise the temperature to 90℃ and dry for 20 hours until the moisture content of the blank is less than 1%; S8. Place the dried green body into a high-temperature sintering furnace and sinter according to the following procedure: heat from room temperature to 400℃ at a rate of 1℃ / min and hold for 1 hour; then heat to 900℃ at a rate of 3℃ / min and hold for 2 hours; finally heat to 1300℃ (final stage) at a rate of 4℃ / min and hold for 5 hours (calculated based on a green body thickness of 15mm, with 1.0h corresponding to every 10mm). After sintering, allow the green body to cool naturally to room temperature in the furnace.

[0033] Example 3 Raw material ratio (by weight): Aluminosilicate fiber (with Al2O3 content ≥62%, fiber length 5-20mm): 50 parts; Yttrium-stabilized zirconia powder (median particle size 3-5 μm): 25 parts; Activated alumina powder (median particle size 2-3 μm): 15 parts; Yttrium oxide (purity ≥ 99%): 5 parts; Short-cut silicon carbide fibers (1-2 mm in length, 10-15 μm in diameter): 10 parts; Composite sintering aid: 8 parts (prepared by mixing silica sol and aluminum sol in a 1:1 ratio and adding 10% zinc borate), wherein the preparation method is carried out in accordance with claim 1; Hexagonal boron nitride powder (median particle size 0.5-1μm): 4 parts; Preparation process: S1. Put 50 parts of aluminosilicate fiber and 10 parts of chopped silicon carbide fiber into an opening machine for opening and dispersion treatment for 8 minutes until the fiber clumps are completely broken up. S2. Add 25 parts of yttrium-stabilized zirconia powder, 15 parts of activated alumina powder, 5 parts of yttrium oxide, 4 parts of hexagonal boron nitride powder and 8 parts of composite sintering aid to a planetary ball mill, use zirconia balls as the grinding medium, the ball-to-material ratio is 3.5:1, the speed is 350 rpm, and the ball milling is performed for 4 hours to obtain a uniform mixed powder.

[0034] S3. Add the fiber pretreated in S1 and all the mixed powder obtained in S2 into a high-speed mixer and dry mix at 1800 rpm for 30 minutes to obtain a mixture in which the fiber and powder are evenly dispersed. S4. Add 22 parts of silica sol (30% solid content) to the mixture in S3 as a molding binder, put it into a vacuum mixer, and stir for 20 minutes under a vacuum of -0.09MPa to make a uniform, bubble-free plastic slurry. S5. Pour the slurry into a rectangular mold with dimensions of 200mm×200mm×25mm, turn on the vacuum system, and filter for 6 minutes to form a wet blank; S6. Transfer the wet blank along with the mold to the molding press and press it under pressure of 30MPa for 5 minutes to form the shape; S7. Place the formed green body in a forced-air drying oven and dry at 80℃ for 24 hours, then raise the temperature to 120℃ and dry for another 24 hours, until the moisture content of the green body is less than 1%; S8. Place the dried green body into a high-temperature sintering furnace and sinter according to the following procedure: heat from room temperature to 500℃ at a rate of 3℃ / min and hold for 1.5 hours; then heat to 1000℃ at a rate of 5℃ / min and hold for 3 hours; finally heat to 1350℃ (final stage) at a rate of 8℃ / min and hold for 8 hours (calculated based on a green body thickness of 25mm, with 1.5 hours corresponding to every 10mm). After sintering, allow the green body to cool naturally to room temperature in the furnace.

[0035] Comparative example: Commercially available high-purity aluminosilicate ceramic fiber modules (Al2O3 content ≥62%, bulk density ~220kg / m³) were used. -3 )

[0036] The thermal insulation prefabricated component prepared in Example 1 was installed in the radiant section of an ethylene cracking furnace. After one operating cycle (approximately 8000 hours), the average temperature of the furnace outer wall in this area was 45°C, which was 23°C lower than that of the adjacent area where the comparative product was used (average outer wall temperature of 68°C). Moreover, the thermal insulation layer structure was intact with no visible shrinkage seams, resulting in significant energy-saving and safety benefits.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process, characterized in that, The material includes a thermal insulation layer, which is made of the following raw materials in parts by weight: 50-80 parts of aluminum silicate fiber, 10-25 parts of stabilized zirconia powder, 5-15 parts of activated alumina powder, 1-5 parts of rare earth oxides, 3-10 parts of chopped silicon carbide fiber, 2-8 parts of composite sintering aid, and 1-4 parts of hexagonal boron nitride powder. The preparation method of the composite sintering aid includes: mixing silica sol and aluminum sol at a mass ratio of 1:(0.5-2), stirring at 40-60℃ for 0.5-1.5h, then adding zinc borate equivalent to 5%-15% of the total mass of the mixture, and continuing to stir for 2-4h to obtain the final product.

2. The high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process according to claim 1, characterized in that: The stabilized zirconium oxide powder is yttrium-stabilized zirconium oxide or calcium-stabilized zirconium oxide, and its median particle size is 1-5 μm; the median particle size of the activated alumina powder is 0.5-3 μm.

3. The high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process according to claim 1, characterized in that: The rare earth oxide is at least one of yttrium oxide, cerium oxide, and lanthanum oxide; the length of the chopped silicon carbide fiber is 0.1-2 mm, and the diameter of its single filament is 5-15 μm.

4. The high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process according to claim 1, characterized in that: The aluminum silicate fiber contains ≥62% Al2O3 by mass and has a fiber length of 3-20 mm; the hexagonal boron nitride powder has a median particle size of 0.1-1 μm.

5. The high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process according to claim 1, characterized in that: The insulation layer is an integral prefabricated component made by high-temperature sintering, with a bulk density of 350-480 kg / m³. The increase in bulk density is mainly achieved by adding high-density fillers such as stabilized zirconia powder and activated alumina powder, as well as the molding step in the preparation process.

6. The high-temperature resistant insulation layer for a pyrolysis furnace and its preparation process according to claim 5, characterized in that: The insulation layer was tested according to GB / T5988-2022 "Test Method for Permanent Linear Change of Refractory Materials under Heating", and the absolute value of the permanent linear change under heating at 1250℃×24h was not greater than 0.25%.

7. The preparation process of a high-temperature resistant insulation layer for a pyrolysis furnace according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Aluminosilicate fibers and chopped silicon carbide fibers are subjected to an opening and dispersion pretreatment; S2. The stabilized zirconium oxide powder, activated alumina powder, rare earth oxide, hexagonal boron nitride powder and the composite sintering aid are mixed and ball-milled to obtain a uniform mixed powder. S3. Dry mix the fiber pretreated in S1 with the mixed powder obtained in S2; S4. Add a molding binder to the mixture in S3 and perform vacuum stirring to prepare a uniform plastic slurry; the molding binder is silica sol or aluminum sol, and its addition amount is 15%-20% of the total mass of the mixture, and the specific amount is adjusted according to the rheological properties of the required slurry; S5. The slurry is injected into a mold and formed into a wet blank by vacuum filtration; S6. The wet blank is subjected to molding or cold isostatic pressing at a pressure of 10-30 MPa; S7. Perform segmented drying on the shaped blank; S8. The dried green body is subjected to staged high-temperature sintering: first, the temperature is increased to 400-500℃ at 1-3℃ / min and held at that temperature, then the temperature is increased to 900-1000℃ at 2-5℃ / min and held at that temperature, and finally the temperature is increased to 1250-1380℃ at 3-8℃ / min and held at that temperature for 4-8 hours. The holding time of the final stage is determined according to the thickness of the green body, and it is cooled with the furnace.

8. The preparation process of a high-temperature resistant insulation layer for a pyrolysis furnace according to claim 7, characterized in that: The final stage temperature of the staged high-temperature sintering is 1280-1350℃; the holding time of the final stage is estimated to be 1.0-1.5h for every 10mm of green body thickness.

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