A coating material for the wall of a tank-type calcining furnace and a method for preparing the coating.

Abstract

This invention provides a coating material for the wall of a tank-type calcining furnace and a method for preparing the coating. The coating material comprises a first fine powder or a second fine powder, solid additives, and liquid additives. The mass ratio of the first fine powder or the second fine powder, the liquid additives, and the solid additives is 100:8-13:0.9-2.2. The first fine powder comprises the following substances by weight percentage: 60-80% fused silica fine powder, 10-20% silicon carbide fine powder, 3-8% silicon nitride powder, 2-6% spherical silica powder, and 2-6% spodumene. The second fine powder comprises the following substances by weight percentage: 60-80% fused corundum fine powder, 10-20% α-alumina fine powder, 5-10% chromium oxide fine powder, 2-6% spherical silica powder, and 2-6% spodumene. The coating material for the tank wall of the calcining furnace and the preparation method of the coating provided by the present invention improve the erosion and corrosion resistance of the silica brick products for the tank wall of the calcining furnace, reduce the corrosion of silica bricks by impurities such as sulfur and vanadium in petroleum coke, improve the production efficiency of the calcining furnace, and extend the service life of the calcining furnace.

Description

Technical Field

[0001] This invention relates to the field of refractory materials, and more particularly to a coating material for the wall of a calcining furnace and a method for preparing the coating. Background Technology

[0002] The tank-type calciner is one of the main pieces of equipment for calcining petroleum coke. The petroleum coke is heated and calcined inside the tank at 1200℃~1500℃ in the absence of air, burning off the volatile components in the petroleum coke material to form carbon raw materials. The calcined carbon raw materials are the main raw materials used in the production of carbon products. The material used to build the walls of the tank-type calciner is silica refractory brick with a SiO2 content greater than 95%, commonly known as silica brick. The sulfur content in petroleum coke varies, with high-quality petroleum coke having a sulfur content greater than 5.5%. In recent years, due to material cost factors, the proportion of high-sulfur petroleum coke raw materials used in calcining petroleum coke has increased. This has also increased the content of impurities such as sulfur and vanadium in the calcining furnace tank. These impurities have caused great damage and erosion to the silica bricks used to build the tank walls, resulting in phenomena such as dissolution, delamination, pitting, and depressions on the inner wall of the silica bricks. This has led to severe erosion and damage to the silica bricks on the inner wall of the tank, reducing the lifespan of the calcining furnace from the original 7-8 years to the current 2-3 years before requiring gradual maintenance or major repairs, thus shortening the service life of the calcining furnace.

[0003] To prevent damage to the inner wall of the tank from low-melting-point impurities such as sulfur and vanadium in high-sulfur petroleum coke feedstock, existing refractory coating materials, such as the refractory coating material disclosed in patent document CN1058225A, are composed of a concentrated aqueous solution of alkaline silicate and heat-resistant inorganic fillers. However, they require micro-bladder-like structures that expand upon heating as foaming aids. After being heated to 120°C, their volume expansion coefficient is at least 20 times their original volume to improve the effectiveness of the alkaline silicate containing the refractory coating material. This material is mainly used for heat-resistant and fireproofing of steel structures in buildings. However, at temperatures above 1200°C in tank calcining furnaces, the preheated expansion layer melts and fails to protect the inner wall of the furnace. It also lacks resistance to the erosion of petroleum coke and the corrosion of impurities such as sulfur and vanadium. Therefore, the refractory coating disclosed in this invention is not suitable for the tank walls of tank calcining furnaces. Patent document CN111073460A discloses a refractory coating for high-temperature environmental protection equipment and its preparation method. The refractory coating comprises, from the inside out, a refractory layer, a sandblasting layer, and a heat-insulating layer. The refractory layer comprises 2-6 parts copper powder, 1-3 parts chromium powder, 10-16 parts alumina powder, 2-10 parts asbestos fiber, 1-4 parts niobium powder, 1-9 parts diatomaceous earth, 6-8 parts silane coupling agent, 10-18 parts epoxy resin emulsion, 3-6 parts polypropylene cellulose, 2-6 parts paraffin wax, and amino... 3-10 parts resin; the sandblasting layer includes a silicon carbide granule layer and a gypsum layer; the insulation layer, by weight, includes 5-9 parts peanut shell powder, 2-10 parts corn stalk powder, 3-7 parts wheat straw, 2-12 parts shell powder, and 10-40 parts water; among these, copper powder, niobium powder, asbestos fiber, niobium powder, diatomaceous earth, paraffin wax, gypsum layer, peanut shell powder, corn stalk powder, wheat straw, and shell powder will become harmful impurities in the coating material, making it unsuitable for the protection of silica bricks on the walls of tank-type calcining furnaces that calcine petroleum coke. Patent document CN107841169A discloses a refractory coating for high-temperature environmental protection equipment and its preparation method. The refractory coating disclosed in the document includes 16 parts of silicon powder, 4 parts of copper powder, 3 parts of chromium powder, 12 parts of alumina powder, 9 parts of iron oxide powder, 7 parts of silicon carbide powder, 13 parts of beryllium oxide, 8 parts of lanthanum oxide, 30 parts of calcium oxide, and 17 parts of manganese nitride. Among them, copper powder, iron oxide powder, calcium oxide, manganese nitride, etc. can become harmful impurities in the coating material, and are not suitable for the protection of silica bricks on the walls of tank furnaces for calcining petroleum coke.Patent document CN109504137A describes a high-temperature resistant and wear-resistant coating material for boiler water-cooled walls and its preparation method. The material protects the boiler water-cooled walls, primarily from the wear and corrosion caused by long-term scouring of unburned coal particles and burnt fly ash, thus achieving anti-corrosion and wear-resistant effects. However, the petroleum coke calcined in a calcining furnace is directly in contact with silica bricks inside the furnace wall for high-temperature roasting. The environment it faces includes moisture, scouring from the discharged petroleum coke material, and corrosion from sulfur and alum in the petroleum coke. Alum is particularly corrosive to silica bricks. The two applications are in different environments, and the coating material in patent document CN109504137A contains light magnesium oxide and titanium oxide, making it unsuitable for tank-type calcining furnaces used for calcining petroleum coke.

[0004] Therefore, how to improve the erosion and corrosion resistance of silica brick products on tank walls, reduce the erosion of silica bricks by impurities such as sulfur and vanadium from petroleum coke, and improve the production efficiency of tank calcining furnaces has become the key to extending the service life of tank calcining furnaces. Summary of the Invention

[0005] The purpose of this invention is to provide a coating material for the tank wall of a calcining furnace and a method for preparing the coating, thereby improving the erosion and corrosion resistance of the silica brick products for the tank wall of the calcining furnace, reducing the erosion of silica bricks by impurities such as sulfur and vanadium from petroleum coke, improving the production efficiency of the calcining furnace, and extending the service life of the calcining furnace.

[0006] To solve the above-mentioned technical problems, the present invention provides a coating material for the tank wall of a tank-type calcining furnace and a method for preparing the coating, which is achieved as follows:

[0007] A coating material for the wall of a tank-type calcining furnace includes a first fine powder or a second fine powder, solid additives, and liquid additives; the mass ratio of the first fine powder or the second fine powder, the liquid additives, and the solid additives is 100:8-13:0.9-2.2; the first fine powder includes the following substances by weight percentage: 60-80% fused silica powder, 10-20% silicon carbide powder, 3-8% silicon nitride powder, 2-6% spherical silica powder, and 2-6% spodumene; the second fine powder includes the following substances by weight percentage: 60-80% fused silica powder, 10-20% silicon carbide powder, 3-8% silicon nitride powder, 2-6% spherical silica powder, and 2-6% spodumene; The powder comprises 80% fused alumina fine powder, 10-20% α-alumina fine powder, 5-10% chromium oxide fine powder, 2-6% spherical silica powder, and 2-6% spodumene; the liquid additive for the first fine powder is silica sol, and the liquid additive for the second fine powder is aluminum dihydrogen phosphate; the solid additives include methyl cellulose, boric acid, and sodium hexametaphosphate, wherein the weight percentage of each substance in the first or second fine powder is: 0.2-1.0% methyl cellulose, 0.2-0.5% boric acid, and 0.2-1.0% sodium hexametaphosphate.

[0008] This invention utilizes fused silica, a high-purity silica material with excellent high-temperature resistance, chemical stability, and mechanical strength. In coatings, fine fused silica powder enhances the hardness and wear resistance of the coating. Fine silicon carbide powder, a high-temperature resistant and high-hardness ceramic material with excellent wear resistance and chemical inertness, further increases the hardness and wear resistance of the coating, improving its anti-friction properties. Fine silicon nitride powder, a high-temperature resistant and high-strength material with excellent thermal shock resistance and chemical stability, enhances the heat resistance and corrosion resistance of the coating. Adding more than 8% silicon nitride does not significantly alter the effect and increases costs. When these three materials are combined, they complement each other, forming a composite coating that comprehensively leverages their respective performance advantages. Fine fused silica powder provides hardness and wear resistance, fine silicon carbide powder increases wear resistance, and fine silicon nitride powder improves heat resistance, collectively protecting the substrate and enhancing the overall performance of the coating.

[0009] Silica sol, as a high-temperature binder for fine powders, can uniformly mix with particulate materials in the coating to form a homogeneous coating system, ensuring the uniformity and density of the coating. It forms a good bond, improving the adhesion between the coating and the substrate, and increasing the stability and durability of the coating. Silica sol remains stable at high temperatures, is not easily combustible or decomposed, and its low coefficient of thermal expansion and contraction allows the coating to remain stable under temperature changes, preventing cracking or peeling. Silica sol can better promote the bonding between various materials, forming a uniform and stable composite coating, improving the coating's performance and durability.

[0010] Both fused alumina fine powder and chromium oxide fine powder possess high hardness and wear resistance, which can improve the hardness and abrasion resistance of the coating. Alpha-alumina fine powder has good mechanical strength and toughness; when mixed with fused alumina and chromium oxide fine powder, it can improve the strength and toughness of the coating. Chromium oxide and fused alumina fine powder undergo a chemical reaction at high temperatures to form aluminum chromate, improving the mechanical and heat resistance of the coating. Furthermore, the solid solution formation of chromium oxide fine powder at high temperatures alters the hardness and density of the fused alumina fine powder, enhancing the strength and toughness of the coating and reducing its coefficient of thermal expansion. The three fine powders—fused alumina, alpha-alumina, and chromium oxide—have different coefficients of thermal expansion, with fused alumina fine powder having the lowest and alpha-alumina the highest. Their interaction after mixing reduces the overall thermal expansion performance of the coating.

[0011] Aluminum dihydrogen phosphate undergoes a hydrolysis reaction at high temperatures to form aluminum hydroxide colloid, which acts as a binder and solidifier for the second fine powder. Its bonding strength and stability are higher than those of silica sol, making it more suitable as a binder for fused corundum fine powder, chromium oxide, and α-alumina, which have higher hardness.

[0012] The coating material of the present invention is prepared by adding spodumene with a specific gravity of not less than 1.35 g / cm³. 3 The aluminum dihydrogen phosphate liquid or silica sol allows the coating material to be sprayed onto the inner wall of the silica brick wall of the calcining furnace without dripping or cracking. It bonds to the silica brick wall under natural conditions, initially setting and solidifying at 50-80℃, providing adhesive strength. At 750-800℃, it undergoes a bonding reaction with the material, gradually sintering with the silica brick wall surface. Complete sintering occurs at 1250℃, protecting the silica brick.

[0013] A small amount of silica powder can fill the gaps and cracks in the coating, increasing its density and compactness, and improving its fire resistance. It can also increase the coating's hardness and wear resistance, extending its service life. Furthermore, it can reduce the coating's coefficient of thermal expansion, decreasing the likelihood of deformation and cracking at high temperatures. Finally, it can be fully mixed with fine powder to enhance the adhesion between the coating and the substrate, preventing the coating from peeling off.

[0014] Spodumene can reduce the coefficient of thermal expansion of coatings. Its low coefficient of thermal expansion reduces the thermal expansion of materials at high temperatures, thus lowering the risk of thermal shock damage. It also enhances the refractory properties of coatings, making them more resistant to high temperatures and corrosion. Furthermore, spodumene improves the thermal stability and thermal shock resistance of refractory materials, resulting in better stability and durability under high-temperature conditions. Finally, the addition of spodumene effectively reduces the thermal conductivity of materials, improving their insulation properties.

[0015] In the first fine fraction, the fineness of the fused silica powder is greater than 300 mesh. Combined with spherical silica powder, spodumene, and other materials, it is easier to form a mullite phase, which improves the density of the coating material. The spherical silica powder and spodumene can act as a catalyst to increase the curing speed of the coating material, thereby increasing the adhesion between the coating material and the wall silica bricks. This can increase the hardness of the coating material, while also improving the adhesion, hardness, and wear resistance of the coating material, and increasing the corrosion resistance of the coating material in harsh environments such as high humidity.

[0016] Silicon nitride powder with a fineness greater than 300 mesh is an excellent material for resisting corrosion by compounds such as sulfur and lum. When used in combination with fine silicon carbide powder, and by adding materials such as spherical silicon micro powder and spodumene, a glaze layer can be formed on the surface of the coating, which further improves the hardness and wear resistance of the coating material and increases its corrosion resistance in harsh environments.

[0017] Methylcellulose, boric acid, and sodium hexametaphosphate are added to the coating as auxiliary materials. Methylcellulose acts as a binder, helping to fix other particles and improving the coating's formability and stability. The addition of flame retardants such as boric acid and sodium hexametaphosphate can improve the coating's flame retardant properties, reduce its flammability, and improve fire safety.

[0018] Optionally, the coating further includes: a base film adhesive, wherein the base film adhesive has a specific gravity of not less than 1.35 g / cm³. 3 Liquid water glass.

[0019] Liquid water glass is a colorless and transparent colloidal solution, mainly composed of sodium silicate or potassium silicate. It is composed of amorphous silica polymers and water molecules. It has high viscosity, good heat resistance, and can withstand high temperatures without decomposing. It also has a certain degree of corrosion resistance to many chemicals, which can protect the surface of the coated object. When liquid water glass comes into contact with moisture or water, it undergoes a hydrolysis reaction to form a colloidal silica gel, which can bond well with the silica refractory bricks on the walls of the calcining furnace.

[0020] Optionally, the first fine powder may further include 13-17% by weight of α-alumina fine powder.

[0021] Adding α-alumina fine powder to the first fine powder material can enhance the overall strength and hardness of the first fine powder material, improve its compressive and tensile mechanical properties, and improve its wear resistance.

[0022] Optionally, the second fine powder may further include 3 to 8% by weight of silicon nitride powder.

[0023] Silicon nitride has extremely high hardness, which can significantly improve the hardness and wear resistance of the second fine powder, enhance the mechanical properties of the overall coating material, and improve its tensile and compressive strength; silicon nitride has extremely high chemical stability, which improves the chemical stability and corrosion resistance of the coating material.

[0024] Optionally, the second fine powder may further include 10-20% by weight of silicon carbide fine powder.

[0025] Silicon carbide has higher hardness and thermal conductivity than silicon nitride, and it exhibits better stability at high temperatures. When added to fine powders, it can significantly improve the hardness and wear resistance of the secondary fine powder, enhance the overall mechanical properties of the coating material, and improve its tensile and compressive strength. Silicon nitride has extremely high chemical stability, improving the chemical stability and corrosion resistance of the coating material. Its effects are better than silicon nitride, but silicon nitride is more expensive.

[0026] Optionally, the mass ratio of the second fine powder, liquid additive, and solid additive is 100:12:1.5; the first fine powder comprises the following substances by weight percentage: 80% fused silica fine powder, 10% silicon carbide fine powder, 3% silicon nitride powder, 3% spherical silica micropowder, and 4% spodumene; the solid additive comprises the following substances by weight percentage of the first fine powder: boric acid 0.3%, sodium hexametaphosphate 0.5%, and methyl cellulose 0.5%.

[0027] Optionally, the mass ratio of the second fine powder, liquid additive, and solid additive is 100:12:1.3; the second fine powder comprises the following substances by weight percentage: 75% fused alumina fine powder, 15% α-alumina fine powder, 5% chromium oxide fine powder, 2% spherical silica powder, and 3% spodumene; the solid additive comprises the following substances by weight percentage in the second fine powder: boric acid 0.2%, sodium hexametaphosphate 0.5%, and methyl cellulose 0.8%.

[0028] A method for preparing a coating material for the tank wall of a calcining furnace involves uniformly mixing a first fine powder or a second fine powder, uniformly mixing solid auxiliary materials, pouring the uniformly mixed first or second powder and solid auxiliary materials into a container, adding liquid auxiliary materials and stirring evenly to form a coating material; spraying or brushing a layer of base film adhesive onto the inner wall of the calcining furnace tank, waiting for 8-12 minutes, and then spraying or repeatedly brushing the coating material until the coating thickness is not less than 3 mm.

[0029] Optionally, the base film adhesive has a specific gravity of not less than 1.35 g / cm³. 3 Liquid water glass.

[0030] Optionally, the first fine powder or the second fine powder is mixed evenly by adding it to a mixer and mixing for ≥10 minutes.

[0031] This invention relates to a coating material for the walls of a calcining furnace tank. This material forms a 3mm thick protective layer on the inner wall of the silica brick wall within the furnace tank. At a high temperature of 750-800℃, the coating material gradually sintersects with the silica brick wall through a reaction between the binder and the material. Complete sintering occurs at 1250℃. The sintered coating material adheres firmly to the silica brick surface, forming a smooth glaze layer that is voluminous, non-expanding, and non-shrinking. This coating material not only resists the erosion and corrosion of the silica brick wall by impurities such as sulfur and vanadium in petroleum coke at high temperatures, but also prevents these impurities from eroding the tank wall along the mortar joints of the silica bricks. It also prevents coke adhesion to the surface of the refractory silica bricks, improving the production efficiency of the calcining furnace. The protective layer formed by the coating material prepared according to this invention can extend the service life of the calcining furnace tank wall by 2-3 years. Furthermore, when slight damage to the inner wall of the silica bricks in the tank wall is found during the 3-8 years of use of the tank calciner, machine spraying can be used to repair the damaged surface of the silica bricks, thereby extending the service life of the tank calciner.

[0032] The present invention discloses a coating material for the wall of a tank-type calcining furnace and its preparation method, which has the following beneficial effects:

[0033] 1. The coating material of the present invention can form a 3mm thick protective layer on the inner wall of the silica brick wall of the calcining furnace tank. At a high temperature of 750-800℃, the coating material gradually sinterstalls with the silica brick wall through the bonding reaction between the binder and the material within the coating material. Complete sintering with the silica brick surface is achieved after 1250℃. The sintered coating material adheres firmly to the silica brick surface, forming a smooth glaze layer. It is also volume-stable, without expansion or contraction. This coating material not only resists the erosion and corrosion of the silica brick products on the tank wall by impurities such as sulfur and vanadium in petroleum coke at high temperatures, but also solves the problem of these impurities eroding the tank wall along the mortar joints of the silica bricks. It can also resist the formation of coke adhering to the surface of refractory silica brick products, improving the production efficiency of the tank calcining furnace. The protective layer formed by the coating material prepared by the present invention can extend the service life of the calcining furnace tank wall by 2-3 years.

[0034] 2. The coating material of the present invention can also be used as a repair material when the inner wall of the silica bricks in the tank wall of the calcining furnace is found to be slightly damaged during the 3 to 8 years of use. The damaged surface of the inner wall of the silica bricks can be repaired by machine spraying, thereby extending the service life of the calcining furnace.

[0035] 3. The materials provided by this invention are reasonably matched and readily available, ensuring the performance characteristics of the coating material and improving its performance. Attached Figure Description

[0036] Figure 1 These are cross-sectional views of the silicon brick circular hole crucibles used in Examples 1 to 5 of the present invention; from left to right, they are Examples 1 to 5.

[0037] Figure 2 The present invention relates to the tank body and coating of a tank-type calcining furnace constructed on-site; 1-silica brick wall; 2-inner wall coating layer. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the following embodiments provide a more detailed description of the invention. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0039] The coating material for the tank wall of the calcining furnace of this invention requires the following specifications for each embodiment: fused silica fine powder with a fineness greater than 300 mesh, fused corundum fine powder with a fineness greater than 250 mesh, α-alumina fine powder with a fineness greater than 300 mesh, chromium oxide fine powder with a fineness greater than 300 mesh, silicon carbide fine powder with a fineness greater than 250 mesh, silicon nitride powder with a fineness greater than 300 mesh, spherical silica micropowder with a fineness greater than 300 mesh, and spodumene fine powder with a fineness greater than 200 mesh; the SiO2 content of the fused silica fine powder is greater than 99%, the Al2O3 content of the fused corundum fine powder is greater than 98%, the Al2O3 content of the α-alumina fine powder is greater than 99%, the SiO2 content of the silicon carbide fine powder is greater than 90%, the SiO2 content of the silicon nitride fine powder is greater than 95%, the SiO2 content of the spherical silica micropowder is greater than 90%, and the SiO2 content of the spodumene fine powder is greater than 70%. The specific gravity of the liquid additive, aluminum dihydrogen phosphate or silica sol, is not less than 1.35 g / cm³. 3 The specific gravity of liquid water glass is not less than 1.35 g / cm³. 3 This invention provides specific requirements for the raw materials to ensure the implementation effect of the embodiments. However, these limiting conditions are not essential for achieving the purpose of this invention. Various embodiments for solving the technical problems of this invention are as follows:

[0040] Example 1

[0041] 1.1 The material composition and content of the coating material in this embodiment are shown in Table 1:

[0042] Table 1

[0043]

[0044] The percentage content of boric acid, sodium hexametaphosphate, and methyl cellulose in solid excipients is relative to the mass of the fine powder.

[0045] 1.2 Preparation of coating material:

[0046] Weigh the fine powders according to the above-mentioned weight proportions. Add the weighed fine powders to a mixer and mix for at least 10 minutes to ensure uniform mixing. Then weigh out 27 kg of the uniformly mixed fine powder and package it in a sealed plastic bag for later use.

[0047] Weigh the solid excipients methylcellulose, boric acid, and sodium hexametaphosphate according to the above-mentioned weight proportions, and then pack them into plastic sealed bags for later use.

[0048] Weigh out the liquid auxiliary material silica sol according to the above-mentioned weight proportions, and package it in a sealed plastic bag for later use.

[0049] The specific gravity shall not be less than 1.35 g / cm³ 3 For liquid water glass base film adhesive, weigh out 30KG and put it into a plastic bucket with a sealed lid for warehousing and shipment. The sealed plastic bucket should be marked with the words "base film adhesive".

[0050] Once weighed, one part of coating powder, one part of solid auxiliary material, and one part of liquid auxiliary material are placed into a sealed plastic bucket, it is ready for warehousing and shipment. The sealed plastic bucket is marked with the words "Spraying Powder".

[0051] The 27KG fine powder mentioned above is for packaging purposes only; during use, the fine powder, liquid additives, and solid additives must be mixed according to the mass ratio in Table 1. The 30KG liquid water glass base film adhesive is also for packaging purposes only, and is not for use in the same mass ratio as the fine powder.

[0052] 1.3 On-site coating application:

[0053] 1.3.1 Clean up the site and set up a safety cordon to facilitate construction.

[0054] 1.3.2 Remove all three portions of material from the plastic bucket marked "Spraying Powder". Open the three plastic bags and pour the material into the plastic bucket. Then, use a handheld electric mixer to stir the powder until it forms a uniform, thick paste. Set aside for later use. Open the sealed plastic bucket marked "Base Film Adhesive" and set aside for later use.

[0055] 1.3.3 Manual Application Method: After the silica brick walls of the tank are constructed, clean the residual mortar from the inner wall surface. Manually apply the primer adhesive using a brush or mortar roller. First, spray a layer of primer adhesive onto the inner wall surface of the newly constructed silica brick walls of the calcining furnace tank. After waiting 10 minutes, manually dip the brush or mortar roller into a bucket containing mixed coating material, then repeatedly apply the coating material to the inner wall of the silica brick wall. Apply a coating of at least 3mm on top of the primer. After completion, clean the site thoroughly before proceeding to the next tank, continuing until all calcining furnace tanks are coated.

[0056] 1.3.4 Machine Spraying Method: After constructing the silica brick walls of the tank, clean the residual mortar from the inner wall surface. Place the suction pipe of the spraying machine into the bucket containing the base film adhesive, start the spraying machine, and aim the nozzle at the inner wall of the silica brick wall. First, spray a layer of base film adhesive onto the inner wall surface of the newly constructed silica brick walls of the calcining furnace tank. After waiting for 10 minutes, place the suction pipe of the spraying machine into the bucket containing the mixed coating material, start the spraying machine, and aim the nozzle at the base film on the inner wall of the silica brick wall. Spray a coating of not less than 3mm onto the base film on the inner wall surface of the newly constructed silica brick walls of the calcining furnace tank. After the operation is completed, clean the site thoroughly and proceed to the next tank until all calcining furnace tanks are sprayed.

[0057] Example 2

[0058] The material composition and content of the coating material in this embodiment are shown in Table 2:

[0059] Table 2

[0060]

[0061] The percentage content of boric acid, sodium hexametaphosphate, and methyl cellulose in solid excipients is relative to the mass of the fine powder.

[0062] The preparation method of the coating material and the on-site construction method are the same as in Example 1.

[0063] Example 2

[0064] The material composition and content of the coating material in this embodiment are shown in Table 2:

[0065] Table 2

[0066]

[0067] The percentage content of boric acid, sodium hexametaphosphate, and methyl cellulose in solid excipients is relative to the mass of the fine powder.

[0068] The preparation method of the coating material and the on-site construction method are the same as in Example 1.

[0069] Example 3

[0070] The material composition and content of the coating material in this embodiment are shown in Table 3:

[0071] Table 3

[0072]

[0073]

[0074] The percentage content of boric acid, sodium hexametaphosphate, and methyl cellulose in solid excipients is relative to the mass of the fine powder.

[0075] The preparation method of the coating material and the on-site construction method are the same as in Example 1.

[0076] Compared to Example 2, this embodiment reduces the amount of fused alumina fine powder and increases the amount of silicon carbide fine powder.

[0077] Example 4

[0078] The material composition and content of the coating material in this embodiment are shown in Table 4:

[0079] Table 4

[0080]

[0081] The percentage content of boric acid, sodium hexametaphosphate, and methyl cellulose in solid excipients is relative to the mass of the fine powder.

[0082] The preparation method of the coating material and the on-site construction method are the same as in Example 1.

[0083] Example 5

[0084] The material composition and content of the coating material in this embodiment are shown in Table 5:

[0085] Table 5

[0086]

[0087] The percentage content of boric acid, sodium hexametaphosphate, and methyl cellulose in solid excipients is relative to the mass of the fine powder.

[0088] Compared to Example 1, this embodiment reduces the amount of fused silica powder and increases α-alumina powder; the preparation method of the coating material and the on-site construction method are the same as in Example 1.

[0089] Example 6

[0090] Table 6

[0091]

[0092]

[0093] This embodiment is based on Embodiment 1, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0094] Example 7

[0095] Table 7

[0096]

[0097] This embodiment is based on Embodiment 1, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0098] Example 8

[0099] Table 8

[0100]

[0101]

[0102] This embodiment is based on Embodiment 5, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0103] Example 9

[0104] Table 9

[0105]

[0106]

[0107] This embodiment is based on Embodiment 5, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0108] Example 10

[0109] Table 10

[0110]

[0111] This embodiment is based on Embodiment 2, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0112] Example 11

[0113] Table 11

[0114]

[0115]

[0116] This embodiment is based on Embodiment 2, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0117] Example 12

[0118] Table 12

[0119]

[0120] This embodiment is based on Embodiment 3, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0121] Example 13

[0122] Table Thirteen

[0123]

[0124]

[0125] This embodiment is based on Embodiment 3, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0126] Example 14

[0127] Table 14

[0128]

[0129] This embodiment is based on Embodiment 4, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0130] Example 15

[0131] Table 15

[0132]

[0133] This embodiment is based on Embodiment 4, but with adjustments to the component content. The coating material preparation method and coating application method are the same as in Embodiment 1.

[0134] Experimental example:

[0135] Small samples were prepared according to the proportions described in Examples 1-5 for testing. Five silica bricks were taken, and drilling was performed on the bricks. The crucibles were shaped with a 50mm deep circular hole. The coating materials in the proportions described in Examples 1 to 5 were applied to the inner walls of the circular holes of the five silica bricks according to the methods described in the examples. After 24 hours of natural solidification, petroleum coke raw material with a sulfur content greater than 5.5% was taken and filled into the circular holes of the silica bricks. The crucibles were covered with a cover plate and placed in a kiln to be heated to 1350°C for calcination. After calcination and cooling, the petroleum coke was poured out. The coating material was observed to be intact and smooth, with no traces of erosion.

[0136] To further verify the anti-corrosion effect of the coating material, the silica brick crucible, which had undergone its first calcination, was refilled with fresh petroleum coke raw material with a sulfur content greater than 5.5%, covered, and placed back into the kiln for calcination at 1350℃. After 10 such repeated calcinations, the silica brick crucible was then cut in half from the middle, and the erosion condition of the cross-section was observed. Figure 1 This is the cross-section of the round-hole crucible coated in Example 1, such as... Figure 1 The coating material shown is completely and firmly bonded to the silica bricks. The coating material is not significantly penetrated by the sulfur in the petroleum coke. The coating material is clearly visible and the surface is smooth and complete. Visual observation shows that the coating effect of Examples 1, 2, and 5 is better than that of Examples 3 and 4. The best effect is shown in Examples 1 and 5. However, the formulation schemes of Examples 1 to 5 all achieve the purpose of resisting the corrosion of silica brick products on the tank wall by impurities such as sulfur and vanadium in the petroleum coke at high temperature. Figure 2 This is a photograph of the actual coating on the wall of the tank-type calcining furnace of this invention.

[0137] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coating material for the wall of a tank-type calcining furnace, characterized in that, The mixture comprises a first or second fine powder, solid additives, and liquid additives; the mass ratio of the first or second fine powder, liquid additives, and solid additives is 100:8-13:0.9-2.2; the first fine powder comprises the following substances by weight percentage: 60-80% fused silica powder, 10-20% silicon carbide powder, 3-8% silicon nitride powder, 2-6% spherical silica powder, and 2-6% spodumene; the second fine powder comprises the following substances by weight percentage: 60-80%... The powder comprises fused corundum fine powder, 10-20% α-alumina fine powder, 5-10% chromium oxide fine powder, 2-6% spherical silica micropowder, and 2-6% spodumene; the liquid additive for the first fine powder is silica sol, and the liquid additive for the second fine powder is aluminum dihydrogen phosphate; the solid additives include carboxymethyl cellulose, boric acid, and sodium hexametaphosphate, accounting for the following weight percentages of the first or second fine powder: carboxymethyl cellulose 0.2-1.0%, boric acid 0.2-0.5%, and sodium hexametaphosphate 0.2-1.0%.

2. The coating material for the tank wall of the calcining furnace according to claim 1, characterized in that, The first fine powder also includes 10-20% by weight of α-alumina fine powder.

3. The coating material for the tank wall of the calcining furnace according to claim 1, characterized in that, The second fine powder also includes silicon nitride powder at a weight percentage of 3 to 8%.

4. The coating material for the tank wall of the calcining furnace according to claim 1, characterized in that, The second fine powder also includes 10-20% by weight of silicon carbide fine powder.

5. The coating material for the tank wall of the calcining furnace according to claim 1, characterized in that, The mass ratio of the first fine powder, liquid additive, and solid additive is 100:12:1.

3. The first fine powder comprises the following substances by weight percentage: 80% fused silica fine powder, 10% silicon carbide fine powder, 3% silicon nitride powder, 3% spherical silica micropowder, and 4% spodumene. The solid additive comprises the following substances by weight percentage in the first fine powder: boric acid 0.3%, sodium hexametaphosphate 0.5%, and carboxymethyl cellulose 0.5%.

6. The coating material for the tank wall of the calcining furnace according to claim 1, characterized in that, The mass ratio of the second fine powder, liquid additive, and solid additive is 100:12:1.

5. The second fine powder comprises the following substances by weight percentage: 75% fused alumina fine powder, 15% α-alumina fine powder, 5% chromium oxide fine powder, 2% spherical silica powder, and 3% spodumene. The solid additives comprise the following substances by weight percentage in the second fine powder: 0.2% boric acid, 0.5% sodium hexametaphosphate, and 0.8% carboxymethyl cellulose.

7. The method for preparing the coating for the tank wall of the tank-type calcining furnace as described in claim 1, characterized in that, Mix the first or second fine powder evenly, mix the solid auxiliary materials evenly, pour the evenly mixed first or second powder and solid auxiliary materials into a container, add liquid auxiliary materials and stir evenly to form a coating material; spray or brush a layer of base film adhesive onto the inner wall of the tank wall of the tank-type calcining furnace, wait 8-12 minutes, and then spray or repeatedly brush the coating material until the coating thickness is not less than 3 mm. The base film adhesive has a specific gravity of not less than 1.35 g / cm³. 3 Liquid water glass.

8. The method for preparing the coating material for the tank wall of the tank-type calcining furnace according to claim 7, characterized in that, The first or second fine powder is mixed evenly by adding it to a mixer and mixing for ≥10 minutes.

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