Method for prolonging service life and saving energy of blast furnace air supply pipeline

Abstract

According to the method, a bonding layer and a thermal barrier layer are arranged on an air supply pipeline base body, so that the surface temperature of the air supply pipeline is reduced, the burn-through possibility of a hot air pipeline is reduced, the heat loss of hot air is reduced, and the service life of the hot air pipeline is prolonged, and energy is saved; the bonding layer and the thermal barrier layer are sequentially attached to the pipeline base body, the thermal barrier layer comprises thermal insulation filler, and the thermal insulation filler is internally provided with a micropore structure; the thermal barrier layer containing the thermal insulation filler is arranged on the air supply pipeline, and the thermal insulation filler belongs to a high-filling-structure material and has the advantages of being small in heat conductivity coefficient, small in stacking density (a good thermal insulation effect can be achieved with small mass), small in surface area, high in weather resistance and the like. Air in the micropore structure cannot generate heat convection after being heated at high temperature, a stable and efficient heat shielding layer is formed in the thermal barrier layer, heat insulation of the thermal barrier layer is achieved, and then the energy-saving and service life prolonging effects of the air supply pipeline are improved.

Description

Technical Field

[0001] The present application relates to the technical field of blast furnace ironmaking, and in particular to a method for extending the life of a blast furnace air supply duct and saving energy. Background Art

[0002] The blast furnace air supply duct device is an important device for delivering hot air (temperature of 1150-1250℃, pressure of 0.3-0.5MPa) in the hot air surrounding pipe into the blast furnace, among which the direct blowing pipe is the key vulnerable part of the air supply duct device. The outer shell of the direct blowing pipe is made of steel, and the inside is lined with a refractory layer. Due to the limitation of the surrounding space position, the diameter of the direct blowing pipe cannot be too large, and the pipe body cannot adopt a water cooling structure. During use, the surface temperature is often too high, and even red heat may occur. In severe cases, it may cause burn-through, and the wind needs to be stopped for replacement, which has a serious impact on ironmaking production. In addition, the difficulty in achieving both the strength and thermal insulation performance of refractory materials also leads to the above phenomenon. Refractory materials with higher strength often have poor thermal insulation performance, resulting in increased surface temperature, which not only causes a large amount of heat loss, but also affects its service life. On the contrary, refractory materials with better thermal insulation performance have lower strength and are difficult to resist the erosion of high-temperature wind, which also makes their life short. Similarly, the goosenecks and elbows in the air supply duct installation also have the same problem.

[0003] In the field of blast furnace technology, heat transfer and loss in high temperature environments is a key issue. In order to reduce energy consumption during blast furnace operation and improve energy efficiency, effective insulation measures need to be taken. Traditional refractory materials often have problems such as high thermal conductivity, large mass, and poor weather resistance, which makes it difficult to meet the high requirements of blast furnace ironmaking for thermal insulation materials. Summary of the invention

[0004] The present application provides a method for extending the life and saving energy of a blast furnace air supply duct, so as to improve the energy-saving effect of the heat-insulated duct.

[0005] In the first aspect, the present application provides a method for extending the life and saving energy of a blast furnace air supply duct, wherein an adhesive layer and a thermal barrier layer are arranged on a duct substrate of the air supply duct; the adhesive layer and the thermal barrier layer are sequentially attached to the duct substrate, the thermal barrier layer comprises a thermal insulating filler, and the thermal insulating filler has a microporous structure inside.

[0006] As an optional embodiment, the thermal barrier layer includes a first thermal barrier layer and a second thermal barrier layer, wherein the first thermal barrier layer is arranged on the outer side of the steel shell of the pipeline substrate, and the second thermal barrier layer is arranged on the inner side of the pipeline substrate, between the steel shell and the refractory material.

[0007] As an optional implementation manner, the thickness of the first thermal barrier layer is 2 mm to 5 mm; and / or

[0008] The thickness of the second thermal barrier layer is 2 mm to 5 mm.

[0009] As an optional embodiment, the particle size of the thermal insulation filler is 50 μm to 200 μm; and / or

[0010] The heat-insulating filler includes at least one of hollow glass or ceramic microspheres.

[0011] As an optional embodiment, the thermal barrier layer further comprises refractory fibers, and the refractory fibers include at least one of mullite fibers, alumina fibers, or zirconia fibers.

[0012] As an optional embodiment, the components of the thermal barrier layer include, by mass fraction: 5% to 20% quartz powder, 5% to 20% corundum powder, 5% to 20% mullite powder, 2% to 10% wollastonite powder, 40% to 70% thermal insulation filler, 2% to 10% refractory fiber and a binder, wherein the binder includes sodium water glass and / or potassium water glass.

[0013] As an optional implementation, the bonding layer is provided between the pipeline base steel shell and the thermal barrier layer.

[0014] As an optional embodiment, the composition of the bonding layer includes, by mass fraction, 10% to 40% quartz powder, 10% to 40% corundum powder, 10% to 40% mullite powder, 5% to 20% wollastonite powder and a binder, wherein the binder includes sodium water glass and / or potassium water glass.

[0015] As an optional implementation, the thickness of the bonding layer is 0.5 mm to 1.0 mm.

[0016] As an optional implementation, the surface roughness of the pipeline base steel shell is 30 μm to 40 μm.

[0017] In a second aspect, the present application provides an iron-making blast furnace, wherein the iron-making blast furnace comprises an air supply duct device, and the air supply duct device comprises the insulated duct provided in the first aspect.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The method provided in the embodiment of the present application is achieved by arranging a thermal barrier layer containing a thermal insulation filler on the air supply duct. The thermal insulation filler is a high-filling structural material with the characteristics of small thermal conductivity, small stacking density (a smaller mass can achieve a better thermal insulation effect), small surface area, and strong weather resistance. The thermal insulation filler has a microporous structure. The air inside the microporous structure will not generate heat convection after being heated at high temperature, and a stable and efficient heat shielding layer is formed in the thermal barrier layer, thereby finally achieving thermal insulation of the thermal barrier layer, thereby improving the energy saving and life extension effects of the air supply duct. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic diagram of the structure of only the blowing pipe in the air supply duct provided in the embodiment of the present application;

[0023] Figure 2 A schematic cross-sectional view of the air supply duct provided in an embodiment of the present application.

[0024] Figure numerals: 1 - pipeline base steel shell, 21 - first thermal barrier layer, 22 - second thermal barrier layer, 3 - refractory material, 4 - bonding layer, 5 - hot air channel, 6 - coal powder channel. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0027] Figure 1 A schematic diagram of the structure of the air supply duct provided in the embodiment of the present application, Figure 2 A cross-sectional schematic diagram of an air supply duct provided in an embodiment of the present application, such as Figure 1 and Figure 2 As shown, an embodiment of the present application provides a method for extending the life of a blast furnace air supply duct and saving energy, wherein an adhesive layer and a thermal barrier layer are arranged on a duct substrate of the air supply duct; the adhesive layer and the thermal barrier layer are sequentially attached to the duct substrate, the thermal barrier layer comprises a thermal insulating filler, and the thermal insulating filler has a microporous structure inside.

[0028] The pipeline matrix, as the main structure of the pipeline, is responsible for bearing the pressure of the medium inside the pipeline and the load of the external environment.

[0029] The thermal barrier layer, which is the core part of the air supply duct, includes thermal insulation fillers. Thermal insulation fillers are a kind of high-filling structural material with the characteristics of low thermal conductivity, low bulk density, small surface area and strong weather resistance. In particular, the thermal insulation filler has a microporous structure inside, which will not produce heat convection after being heated at high temperature, thus forming a stable and efficient heat shielding layer in the thermal barrier layer, effectively blocking the transfer of heat.

[0030] Refractory materials, located on the innermost side of the hot air duct, mainly play the role of protecting the thermal barrier layer from damage by the external high temperature environment, while further improving the fire resistance of the duct.

[0031] Characteristics and advantages of thermal insulation fillers: 1. Low thermal conductivity: Thermal insulation fillers have extremely low thermal conductivity, which can significantly reduce the rate of heat transfer through the pipeline. 2. Low stacking density: Less mass can achieve better thermal insulation effect, reducing the overall mass of the pipeline, which is beneficial to the transportation and installation of the pipeline. 3. Small surface area: Reduces the heat exchange area with the external environment, further improving the thermal insulation effect. 4. Strong weather resistance: Able to maintain stable thermal insulation performance under harsh environmental conditions and extend the service life of the pipeline. 5. Microporous structure: The microporous structure inside the thermal insulation filler will not produce heat convection at high temperatures, forming a stable and efficient heat shielding layer, which is the key to the thermal insulation effect.

[0032] In summary, the method is to set a thermal barrier layer containing thermal insulation filler on the pipeline matrix. The thermal insulation filler is a high-filling structural material with the characteristics of small thermal conductivity, small stacking density (less mass can achieve better thermal insulation effect), small surface area, strong weather resistance, etc. The thermal insulation filler has a microporous structure. The air inside the microporous structure will not generate heat convection after being heated at high temperature, and a stable and efficient heat shielding layer is formed in the thermal barrier layer, ultimately achieving thermal insulation of the thermal barrier layer, thereby improving the energy saving and life extension effects of the air supply duct.

[0033] In some embodiments, the thermal barrier layer includes a first thermal barrier layer and a second thermal barrier layer, wherein the first thermal barrier layer is disposed on the outside of the pipeline substrate, and the second thermal barrier layer is disposed on the inside of the pipeline substrate, and the refractory material is located on the innermost side of the hot air pipeline. Providing thermal barrier layers on both the inside and outside of the pipeline substrate can further improve the thermal insulation effect.

[0034] In some embodiments, the thickness of the first thermal barrier layer is 2 mm to 5 mm; the thickness of the second thermal barrier layer is 2 mm to 5 mm. A suitable thickness of the thermal barrier layer can provide the thermal barrier layer with a good heat insulation effect.

[0035] In some embodiments, the particle size of the thermal insulation filler is 50 μm to 200 μm. Micron-sized thermal insulation fillers have a large specific surface area and can create many static air layers, effectively reducing the thermal conductivity of the thermal barrier layer; too high a particle size will affect the bulk strength of the thermal barrier layer; too low a particle size will increase technical difficulty and cost.

[0036] In some embodiments, the thermal insulation filler includes at least one of hollow glass or ceramic microspheres. Thermal insulation fillers such as hollow glass and ceramic microspheres can reduce heat transfer in the thermal barrier layer because the air inside the thermal insulation fillers such as hollow glass and ceramic microspheres will not undergo thermal convection when heated at high temperatures, thereby reducing the occurrence of thermal convection. At the same time, the thermal barrier layer material with a low thermal conductivity serves as the base material of the thermal barrier layer, and together with the static air layer, forms an effective thermal barrier layer, thereby reducing the thermal conductivity of the thermal barrier layer.

[0037] In some embodiments, the thermal barrier layer further comprises refractory fibers, and the refractory fibers include at least one of mullite fibers, alumina fibers, or zirconia fibers. The addition of refractory fibers can effectively improve the cohesive strength of the thermal barrier layer, prevent the thermal barrier layer from falling off, and increase the service life of the thermal barrier layer.

[0038] In some embodiments, the composition of the thermal barrier layer includes, by mass fraction: quartz powder 5% to 20%, corundum powder 5% to 20%, mullite powder 5% to 20%, wollastonite powder 2% to 10%, thermal insulation filler 40% to 70%, refractory fiber 2% to 10% and a binder, wherein the binder includes sodium water glass and / or potassium water glass.

[0039] Among them, quartz powder has good resistance to acidic medium erosion and can be used in acidic environments. Corundum powder has good chemical stability and wear resistance and can be used in corrosive medium environments. Mullite powder can improve the mechanical strength, thermal shock resistance, chemical stability and wear resistance of the thermal barrier layer. Wollastonite powder can enhance the strength of the thermal barrier layer, improve density and reduce production costs. Controlling the mass usage ratio of each component can make the thermal barrier layer take into account corrosion resistance, mechanical strength, thermal shock resistance, chemical stability and wear resistance.

[0040] Directly preparing the thermal barrier layer on the surface of the pipeline substrate can easily cause the thermal barrier layer to fall off. In some embodiments, the bonding layer is provided between the pipeline substrate and the thermal barrier layer. The bonding layer can improve the difference in thermal expansion behavior between the two, relieve thermal stress, and enable the thermal barrier layer to be well bonded to the pipeline substrate, thereby improving the bonding strength between the thermal barrier layer and the pipeline substrate.

[0041] In some embodiments, the composition of the bonding layer includes, by mass fraction, quartz powder 10% to 40%, corundum powder 10% to 40%, mullite powder 10% to 40%, wollastonite powder 5% to 20% and a bonding agent, wherein the bonding agent includes sodium water glass and / or potassium water glass. The thickness of the bonding layer is 0.5 mm to 1.0 mm.

[0042] Among them, quartz powder has good resistance to acidic medium erosion and can be used in acidic environments. Corundum powder has good chemical stability and wear resistance and can be used in corrosive medium environments. Mullite powder can improve the mechanical strength, thermal shock resistance, chemical stability and wear resistance of the bonding layer. Wollastonite powder can enhance the strength of the bonding layer, improve density and reduce production costs. Controlling the mass usage ratio of each component can make the bonding layer take into account corrosion resistance, mechanical strength, thermal shock resistance, chemical stability and wear resistance.

[0043] In some embodiments, the surface roughness of the pipe substrate is 30 μm to 40 μm.

[0044] The preparation process of the insulated pipe can be: Step 1: clean the dust, grease, etc. on the inner and outer surfaces of the pipe substrate, and wash and dry it; Step 2: grind and roughen the inner and outer surfaces of the pipe substrate to ensure a surface roughness in the range of 30-40μm, and then prepare a bonding layer with a thickness of 0.5mm-1.0mm on the inner and outer surfaces respectively; Step 3: prepare a thermal barrier layer with a thickness of 2mm-5mmm on the surface of the inner and outer bonding layers respectively; Step 4: set a refractory material on the innermost side of the pipe substrate.

[0045] The preparation process of the bonding layer in step 2 is as follows: the base materials are weighed in proportion and mixed evenly, and the bonding agent is added and stirred until uniform to obtain a bonding layer coating. The bonding layer coating is applied to the surface of the pipeline substrate by brushing, pressing, scraping, wiping or high-pressure spraying.

[0046] Preparation of the thermal barrier layer in step 3: weigh the base material in proportion and mix them evenly, add the binder and continue stirring until uniform, to obtain a thermal barrier layer coating. Apply the thermal barrier coating on the surface of the bonding layer by brushing, pressing, scraping, wiping or high-pressure spraying.

[0047] The heat-insulated pipe structure of the embodiment of the present application has the following advantages:

[0048] 1. Application in iron-making blast furnace: The air supply duct structure of the embodiment of the present application is particularly suitable for the high-temperature duct system in the iron-making blast furnace. By using this insulated duct in key parts such as the cooling water duct and the hot air duct of the blast furnace, the heat loss can be significantly reduced and the thermal efficiency of the blast furnace can be improved. At the same time, since the insulated duct is light in weight, the overall load of the blast furnace can also be reduced and the service life of the blast furnace can be extended.

[0049] 2. Energy-saving effect and economic benefits: The air supply duct structure of the present application can significantly improve the energy-saving effect of blast furnace ironmaking. By reducing heat loss, the energy consumption of the blast furnace is reduced, thereby reducing production costs. In addition, since the insulated pipe has a long service life and low maintenance cost, it can also bring significant economic benefits to the enterprise.

[0050] The air supply duct can lower the surface temperature of the duct, reduce burn-through accidents, and increase the life of the duct; at the same time, it can reduce the heat loss of hot air, increase the wind temperature, and reduce the blast furnace fuel ratio, thereby achieving the goal of energy saving and cost reduction.

[0051] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0052] Example 1

[0053] A method for extending the life of a blast furnace air supply duct and saving energy, the process is as follows:

[0054] Step 1: Clean the dust, grease, etc. on the inner and outer surfaces of the pipeline substrate, and clean and dry them; Step 2: Grind and roughen the inner and outer surfaces of the pipeline substrate steel shell to ensure a surface roughness in the range of 30-40μm, and then prepare a bonding layer with a thickness of 0.5mm on the inner and outer surfaces respectively; Step 3: Prepare a thermal barrier layer with a thickness of 3mm on the inner and outer bonding layer surfaces respectively.

[0055] The preparation process of the bonding layer described in step 2 is as follows: the base materials are weighed in proportion and mixed evenly, and the bonding agent is added and stirred until uniform to obtain the bonding layer coating. The bonding layer coating is applied to the surface of the steel shell of the pipeline substrate by high-pressure spraying;

[0056] The coating base material comprises quartz powder (40%), corundum powder (30%), mullite powder (20%) and wollastonite powder (10%);

[0057] The above-mentioned binder is sodium water glass;

[0058] The preparation of the thermal barrier layer in step 3 is as follows: the base materials are weighed in proportion and mixed evenly, and the binder is added and stirred until uniform to obtain a thermal barrier layer coating. The thermal barrier coating is applied on the surface of the bonding layer by high-pressure spraying;

[0059] The coating base material includes quartz powder (20%), corundum powder (15%), mullite powder (10%), wollastonite powder (5%), thermal insulation filler (including hollow glass, ceramic microspheres) (45%), and refractory fiber (5%); wherein the particle size of the thermal insulation filler is 50 μm;

[0060] The above-mentioned binder is sodium water glass;

[0061] The refractory fiber is mullite fiber.

[0062] Example 2

[0063] A method for extending the life of a blast furnace air supply duct and saving energy, the process is as follows:

[0064] Step 1: Clean the dust, grease, etc. on the inner and outer surfaces of the pipeline substrate, and clean and dry it; Step 2: Grind and roughen the inner and outer surfaces of the pipeline substrate steel shell to ensure a surface roughness in the range of 30-40μm, and then prepare a bonding layer with a thickness of 1.0mm on the inner and outer surfaces respectively; Step 3: Prepare a thermal barrier layer with a thickness of 5mm on the surface of the inner and outer bonding layers respectively.

[0065] The preparation process of the bonding layer described in step 2 is as follows: weigh the base materials in proportion and mix them evenly, add the binder and continue to stir until uniform, to obtain the bonding layer coating. Apply the bonding layer coating on the surface of the steel shell of the pipeline base by brushing;

[0066] The coating base material comprises quartz powder (30%), corundum powder (25%), mullite powder (25%) and wollastonite powder (20%);

[0067] The above-mentioned binder is sodium water glass;

[0068] The preparation of the thermal barrier layer in step 3 is as follows: the base material is weighed in proportion and mixed evenly, and the binder is added and stirred until uniform to obtain a thermal barrier layer coating. The thermal barrier coating is applied on the surface of the bonding layer by brushing;

[0069] The coating base material includes quartz powder (12%), corundum powder (10%), mullite powder (10%), wollastonite powder (8%), thermal insulation filler (including hollow glass, ceramic microspheres) (55%), and refractory fiber (5%); wherein the particle size of the thermal insulation filler is 100 μm;

[0070] The above-mentioned binder is sodium water glass;

[0071] The refractory fiber is alumina fiber.

[0072] Comparative Example 1

[0073] An air supply duct adopts a duct matrix.

[0074] Comparative Example 2

[0075] A method for extending the life of a blast furnace air supply duct and saving energy, the process is as follows:

[0076] Step 1: clean the dust, grease, etc. on the inner and outer surfaces of the pipeline substrate, and wash and dry it; Step 2: grind and roughen the inner and outer surfaces of the pipeline substrate to ensure a surface roughness in the range of 30-40μm, and prepare a thermal barrier layer with a thickness of 3mm on the inner and outer surfaces.

[0077] Furthermore, the preparation of the thermal barrier layer described in step 2: weigh the base materials in proportion and mix them evenly, add the binder and continue to stir until uniform, to obtain a thermal barrier layer coating. The thermal barrier coating is applied to the surface of the steel shell of the pipeline substrate by high-pressure spraying;

[0078] The coating base material includes quartz powder (20%), corundum powder (15%), mullite powder (10%), wollastonite powder (5%), thermal insulation filler (including hollow glass, ceramic microspheres) (45%), and refractory fiber (5%); wherein the particle size of the thermal insulation filler is 50 μm;

[0079] The above-mentioned binder is sodium water glass;

[0080] The refractory fiber is mullite fiber.

[0081] By comparison, it can be seen that the surface temperature of Example 1 and Example 2 is 50-150° C. lower than that of Comparative Example 1; and the thermal shock resistance of the thermal barrier layers of Example 1 and Example 2 is 2-4 times higher than that of Comparative Example 2.

[0082] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0083] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b and c can be single or multiple.

[0084] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for extending the life of a blast furnace air supply duct and saving energy, characterized in that: An adhesive layer and a thermal barrier layer are arranged on the pipe substrate of the air supply duct; the adhesive layer and the thermal barrier layer are sequentially attached to the pipe substrate, the thermal barrier layer comprises a thermal insulation filler, and the thermal insulation filler has a microporous structure inside.

2. The method for extending the life of blast furnace air supply ducts and saving energy according to claim 1, characterized in that: The thermal barrier layer comprises a first thermal barrier layer and a second thermal barrier layer, wherein the first thermal barrier layer is arranged on the outer side of the steel shell of the pipeline substrate, and the second thermal barrier layer is arranged on the inner side of the pipeline substrate and is located between the steel shell and the refractory material.

3. The method for extending the life of blast furnace air supply ducts and saving energy according to claim 2, characterized in that: The thickness of the first thermal barrier layer is 2 mm to 5 mm; and / or The thickness of the second thermal barrier layer is 2 mm to 5 mm.

4. The method for extending the life of a blast furnace air supply duct and saving energy according to any one of claims 1 to 3, characterized in that: The particle size of the thermal insulation filler is 50 μm to 200 μm; and / or The heat-insulating filler includes at least one of hollow glass or ceramic microspheres.

5. The method for extending the life of a blast furnace air supply duct and saving energy according to any one of claims 1 to 3, characterized in that: The thermal barrier layer also includes refractory fibers, and the refractory fibers include at least one of mullite fibers, alumina fibers, or zirconia fibers.

6. The method for extending the life of a blast furnace air supply duct according to any one of claims 1 to 3, characterized in that: The components of the thermal barrier layer include, by mass fraction, quartz powder 5% to 20%, corundum powder 5% to 20%, mullite powder 5% to 20%, wollastonite powder 2% to 10%, thermal insulation filler 40% to 70%, refractory fiber 2% to 10% and a binder, wherein the binder includes sodium water glass and / or potassium water glass.

7. The method for extending the life of a blast furnace air supply duct and saving energy according to any one of claims 1 to 3, characterized in that: The bonding layer is arranged between the pipeline base steel shell and the thermal barrier layer.

8. The method for extending the life of blast furnace air supply ducts and saving energy according to claim 7, characterized in that: The components of the bonding layer include, by mass fraction, 10% to 40% quartz powder, 10% to 40% corundum powder, 10% to 40% mullite powder, 5% to 20% wollastonite powder and a bonding agent, wherein the bonding agent includes sodium water glass and / or potassium water glass.

9. The method for extending the life of blast furnace air supply ducts and saving energy according to claim 7, characterized in that: The thickness of the bonding layer is 0.5 mm to 1.0 mm.

10. The method for extending the life of a blast furnace air supply duct and saving energy according to any one of claims 1 to 3, characterized in that: The surface roughness of the pipeline base steel shell is 30 μm to 40 μm.

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