Anti-erosion castable for circulating fluidized bed boiler and preparation method of anti-erosion castable

Abstract

The invention relates to an anti-erosion castable for a circulating fluidized bed boiler and a preparation method of the anti-erosion castable, and belongs to the technical field of castable for circulating fluidized bed boilers. The anti-erosion castable for the circulating fluidized bed boiler comprises the following components in parts by mass: 25-35 parts of fused white corundum, 15-23 parts of corundum composite powder, 10-15 parts of mullite particles, 10-15 parts of sialon bonded silicon carbide, 15-18 parts of modified chrome corundum, 6-8 parts of a binding agent and 3-6 parts of water. According to the anti-erosion castable for the circulating fluidized bed boiler, the corundum powder and the chrome corundum are processed, so that the corundum powder and the chrome corundum have relatively good anti-erosion performance, and the acid and alkali resistance of the anti-erosion castable for the circulating fluidized bed boiler is further improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of castable for circulating fluidized bed boiler, and particularly relates to an erosion-resistant castable for circulating fluidized bed boiler and a preparation method thereof. BACKGROUND

[0002] The circulating fluidized bed boiler is a key equipment of a thermal power plant, and has been rapidly promoted and applied in the world since 1779 due to its high thermal efficiency. The circulating fluidized bed boiler shows great superiority in clean combustion and develops rapidly in China because it can economically and rationally burn low-quality coal. When the circulating fluidized bed boiler is in operation, the inner lining of the boiler is subjected to a large thermal shock. In addition, the circulating fluidized bed boiler usually burns fossil fuels such as coal, and impurities such as sulfur and chlorine contained in the coal can generate acid gases such as sulfuric acid and hydrochloric acid at high temperatures. These substances combine with water in the flue gas to form a corrosive solution, which poses a threat of acid erosion to the inner lining material. At the same time, the alkaline components (such as sodium oxide and potassium oxide) in the coal can form low-melting-point molten alkaline substances at high temperatures, which can cause alkaline erosion of the refractory material and shorten the service cycle of the inner lining of the boiler. Therefore, the inner lining material of the circulating fluidized bed boiler needs to have good resistance to acid gas and slag alkali erosion. SUMMARY

[0003] A first object of the present application is to provide an erosion-resistant castable for a circulating fluidized bed boiler, which has good erosion resistance.

[0004] A second object of the present application is to provide a preparation method of the erosion-resistant castable for the circulating fluidized bed boiler.

[0005] In order to achieve the above objects, the technical scheme adopted by the present application is as follows: An erosion-resistant castable for a circulating fluidized bed boiler, which comprises, by mass fraction: 25-35 parts of fused white corundum, 15-23 parts of corundum composite powder, 10-15 parts of mullite particles, 10-15 parts of sialon bonded silicon carbide, 15-18 parts of modified chromium corundum, 6-8 parts of a bonding agent, and 3-6 parts of water.

[0006] Further, the preparation method of the modified chromium corundum comprises: uniformly mixing TiO2 powder, chromium corundum and phenolic resin, then pressing and forming, drying, calcining and crushing to obtain the modified chromium corundum.

[0007] Further, the mass ratio of the TiO2 powder to the chromium corundum is 1:5-6, and the mass ratio of the chromium corundum to the phenolic resin is 1:0.1-0.2.

[0008] Further, the temperature of drying is 110 DEG C, the time of drying is 5-6 h; the calcination is in nitrogen atmosphere; the temperature rising procedure of calcination is: rising to 450-500 DEG C with the temperature rising rate of 2 DEG C / min, keeping warm for 5-10 h, then rising to 750-800 DEG C with the temperature rising rate of 4 DEG C / min, keeping warm for 5-10 h, finally rising to 1350-1420 DEG C with the temperature rising rate of 3 DEG C / min, keeping warm for 5-6 h, thus the product is obtained.

[0009] Further, the preparation method of the corundum composite powder comprises the following steps: mixing corundum powder, TiO2 powder and TiN powder to obtain corundum mixed powder by ball milling, melting the corundum mixed powder in an electric arc furnace, cooling and crystallizing, and crushing to obtain the product.

[0010] Further, the mass ratio of the corundum powder to the TiO2 powder is 10:0.9-1; the mass ratio of the corundum powder to the TiN powder is 10:0.4-0.5; the temperature of the electric arc furnace is 2000-2500 DEG C.

[0011] Further, the content of Al2O3 in the electrically fused white corundum is ≥99 %, the content of Fe2O3 is ≤0.3 %, the particle size of the electrically fused white corundum is 1-3 mm; the particle size of the mullite particles is 0.5-1 mm; the particle size of the sialon combined silicon carbide is 1-50 µm.

[0012] Further, the modified chromium corundum comprises, by mass percentage: 10-20 % of aggregate with a particle size of 3-5 mm, 20-40 % of aggregate with a particle size of 1-3 mm, 10-20 % of aggregate with a particle size of 0.088-1 mm, and the rest of fine powder with a particle size of <0.088 mm; the particle size of the corundum composite powder is <0.044 mm.

[0013] Further, the binder is silica sol and calcium aluminate cement, the mass of the calcium aluminate cement is 55-78 % of the mass of the binder, and the mass of the silica sol is 22-45 % of the mass of the binder.

[0014] A preparation method of an erosion-resistant castable for a circulating fluidized bed boiler, comprising the following steps: uniformly mixing formula amount of the electrically fused white corundum, the corundum composite powder, the mullite particles, the sialon combined silicon carbide and the modified chromium corundum, then uniformly mixing formula amount of the binder with water, vibration forming, room temperature curing for 12-24 h, and then 110 DEG C keeping warm for 12-24 h, thus the product is obtained.

[0015] The beneficial effects of the present application are: The TiO2 is used as a sintering aid to enhance the compactness of the modified chrome corundum, reduce the porosity of the modified chrome corundum, and delay the diffusion of corrosive substances into the castable. The TiO2 and TiN added to the corundum powder can also increase the compactness of the corundum composite powder, thereby improving the corrosion resistance of the corundum composite powder. The corundum powder and the chrome corundum processed according to the present application have good corrosion resistance, and the acid and alkali resistance of the corrosion-resistant castable for circulating fluidized bed boilers is further improved. DETAILED DESCRIPTION

[0016] The present application will be further described below with reference to the examples.

[0017] The solid content of the phenolic resin is 75 %.

[0018] Example 1 The corrosion-resistant castable for circulating fluidized bed boilers of Example 1 comprises the following raw materials: 35 kg of fused white corundum, 20 kg of corundum composite powder, 10 kg of mullite particles, 10 kg of sialon bonded silicon carbide, 15 kg of modified chrome corundum, 3.3 kg of calcium aluminate cement, 2.7 kg of silica sol, and 4 kg of water. The content of Al2O3 in the fused white corundum is ≥ 99 %, and the content of Fe2O3 is ≤ 0.3 %. The particle size of the fused white corundum is 1-3 mm. The particle size of the mullite particles is 0.5-1 mm. The particle size of the sialon bonded silicon carbide is 1-50 μm.

[0019] The preparation method of the modified chrome corundum comprises the following steps: uniformly mixing 15 kg of chrome corundum, 3 kg of TiO2 powder, and 1.5 kg of phenolic resin, pressing and forming, drying at 110 ℃ for 6 h, then heating to 500 ℃ at a heating rate of 2 ℃ / min under a nitrogen atmosphere, keeping the temperature for 10 h, then heating to 800 ℃ at a heating rate of 4 ℃ / min, keeping the temperature for 5 h, finally heating to 1400 ℃ at a heating rate of 3 ℃ / min, keeping the temperature for 6 h, and then crushing to obtain the modified chrome corundum. The modified chrome corundum comprises, by mass percentage, 20 % of aggregate with a particle size of 3-5 mm, 30 % of aggregate with a particle size of 1-3 mm, 10 % of aggregate with a particle size of 0.088-1 mm, and the remaining amount of fine powder with a particle size of < 0.088 mm.

[0020] The preparation method of the corundum composite powder comprises the following steps: ball milling 20 kg of corundum powder, 1.8 kg of TiO2 powder, and 0.8 kg of TiN powder for 1 h to obtain corundum mixed powder, melting the corundum mixed powder in an electric arc furnace at 2200 ℃, cooling and crystallizing, and then crushing to obtain the corundum composite powder. The particle size of the corundum composite powder is < 0.044 mm.

[0021] The preparation method of the erosion-resistant castable for the circulating fluidized bed boiler of Example 1 comprises the following steps: uniformly mixing the electrically fused white corundum, corundum composite powder, mullite particles, sialon bonded silicon carbide and modified chromium corundum in the formula amount, then adding the silica sol, calcium aluminate cement and water in the formula amount, uniformly mixing, vibration forming, curing at room temperature for 24 h, and then curing at 110 ℃ for 24 h, to obtain the erosion-resistant castable.

[0022] Example 2 The erosion-resistant castable for the circulating fluidized bed boiler of Example 2 comprises the following raw materials: 28 kg of electrically fused white corundum, 15 kg of corundum composite powder, 15 kg of mullite particles, 15 kg of sialon bonded silicon carbide, 18 kg of modified chromium corundum, 6.24 kg of calcium aluminate cement, 1.76 kg of silica sol and 6 kg of water. The content of Al2O3 in the electrically fused white corundum is ≥99 %, and the content of Fe2O3 is ≤0.3 %. The particle size of the electrically fused white corundum is 1-3 mm. The particle size of the mullite particles is 0.5-1 mm. The particle size of the sialon bonded silicon carbide is 1-50 μm.

[0023] The preparation method of the modified chromium corundum comprises the following steps: uniformly mixing 18 kg of chromium corundum, 3 kg of TiO2 powder and 3 kg of phenolic resin, pressing into a shape, drying at 110 ℃ for 6 h, then heating to 450 ℃ at a heating rate of 2 ℃ / min in a nitrogen atmosphere, keeping the temperature for 5 h, then heating to 750 ℃ at a heating rate of 4 ℃ / min, keeping the temperature for 8 h, finally heating to 1420 ℃ at a heating rate of 3 ℃ / min, keeping the temperature for 5 h, and then crushing to obtain the modified chromium corundum. The modified chromium corundum comprises, by mass percentage: 20 % of aggregate with a particle size of 3-5 mm, 40 % of aggregate with a particle size of 1-3 mm, 15 % of aggregate with a particle size of 0.088-1 mm, and the remaining amount of fine powder with a particle size of <0.088 mm.

[0024] The preparation method of the corundum composite powder comprises the following steps: ball-milling 15 kg of corundum powder, 1.5 kg of TiO2 powder and 0.75 kg of TiN powder for 1 h to obtain corundum mixed powder, melting the corundum mixed powder in an electric arc furnace at 2000 ℃, cooling and crystallizing, and then crushing to obtain the corundum composite powder. The particle size of the corundum composite powder is <0.044 mm.

[0025] The preparation method of the erosion-resistant castable for the circulating fluidized bed boiler of Example 2 comprises the following steps: uniformly mixing the electrically fused white corundum, corundum composite powder, mullite particles, sialon bonded silicon carbide and modified chromium corundum in the formula amount, then adding the silica sol, calcium aluminate cement and water in the formula amount, uniformly mixing, vibration forming, curing at room temperature for 20 h, and then curing at 110 ℃ for 12 h, to obtain the erosion-resistant castable.

[0026] Example 3 The anti-erosion castable for circulating fluidized bed boilers in Example 3 comprises the following raw materials: 25 kg of fused white fused alumina, 23 kg of fused alumina composite powder, 13 kg of mullite particles, 13 kg of silane-bonded silicon carbide, 16 kg of modified chromium fused alumina, 4.2 kg of calcium aluminate cement, 2.8 kg of silica sol, and 3 kg of water. The fused white fused alumina contains ≥99% Al₂O₃ and ≤0.3% Fe₂O₃, with a particle size of 1-3 mm. The mullite particles have a particle size of 0.5-1 mm. The silane-bonded silicon carbide has a particle size of 1-50 μm.

[0027] The preparation method of modified chromium corundum includes: mixing 15 kg of chromium corundum, 3 kg of TiO2 powder, and 3 kg of phenolic resin evenly, pressing them into shape, drying them at 110 ℃ for 6 h, then heating them to 480 ℃ at a heating rate of 2 ℃ / min under a nitrogen atmosphere, holding them at that temperature for 8 h, then heating them to 780 ℃ at a heating rate of 4 ℃ / min, holding them at that temperature for 10 h, and finally heating them to 1350 ℃ at a heating rate of 3 ℃ / min, holding them at that temperature for 6 h, and then crushing them to obtain the modified chromium corundum. The modified chromium corundum, by mass percentage, comprises: 15% aggregate with a particle size of 3-5 mm, 30% aggregate with a particle size of 1-3 mm, 20% aggregate with a particle size of 0.088-1 mm, and the remainder being fine powder with a particle size <0.088 mm.

[0028] The preparation method of corundum composite powder includes: ball milling 20 kg of corundum powder, 2 kg of TiO2 powder, and 0.9 kg of TiN powder for 1 h to obtain corundum mixed powder; melting the corundum mixed powder in an electric arc furnace at 2500 ℃; cooling and crystallizing; and crushing to obtain the final product. The particle size of the corundum composite powder is <0.044 mm.

[0029] The preparation method of the anti-erosion castable for circulating fluidized bed boiler in Example 3 includes the following steps: the formula amounts of fused white corundum, corundum composite powder, mullite particles, silane-bonded silicon carbide, and modified chromium corundum are mixed evenly, and then the formula amounts of silica sol, calcium aluminate cement, and water are added and mixed evenly. The mixture is then vibrated and molded, cured at room temperature for 12 h, and then kept at 110 ℃ for 12 h to obtain the final product.

[0030] Comparative Example 1 The preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 1 is roughly the same as that in Example 1. The difference between the preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 1 and Example 1 is that the corundum composite powder is replaced with an equal mass of corundum powder in Comparative Example 1.

[0031] Comparative Example 2 The preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 2 is roughly the same as that in Example 1. The difference between the preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 2 and Example 1 is that the modified chromium corundum is replaced with an equal mass of chromium corundum in Comparative Example 2.

[0032] Comparative Example 3 The preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 3 is roughly the same as that in Example 1. The difference between the preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 3 and Example 1 is that 2.6 kg of TiO2 powder was added in Comparative Example 3.

[0033] Comparative Example 4 The preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 4 is roughly the same as that in Example 1. The difference between the preparation method of the anti-erosion castable for circulating fluidized bed boiler in Comparative Example 4 and Example 1 is that 2.6 kg of TiN powder was added to Comparative Example 4.

[0034] Test case 1. The bulk density and porosity were tested according to GB / T 2997-2015; 2. According to GB / T 30873-2014, the thermal shock resistance performance was tested: the sample was placed in a resistance furnace and kept at 1100 ℃ for 20 min, then removed and placed in room temperature water for 5 min, placed in the air for 5 min, and then placed in the resistance furnace for 20 min. This process was repeated 15 times. 3. Test acid resistance according to GB / T 17601-2023; 4. Alkali resistance was tested according to GB / T 14983-2008; 5. Test the compressive strength at room temperature according to GB / T 5072-2023; 6. Test the permanent linear change rate of heating according to GB / T 5988-2007.

[0035] The test results are shown in Table 1.

[0036] Table 1 Performance test of anti-erosion castables for circulating fluidized bed boilers in Examples 1-3 and Comparative Examples 1-4 As shown in Table 1, the anti-erosion castable for circulating fluidized bed boilers of the present invention possesses excellent thermal shock resistance and erosion resistance. Comparative Examples 1, 3, and 4 show that the blending of TiO2 and TiN can increase the density of corundum powder and reduce porosity, thereby increasing the erosion resistance of the anti-erosion castable for circulating fluidized bed boilers. Comparative Example 2 shows that TiO2 can increase the density of chromium corundum.

[0037] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the content of the present invention's specification shall also be included within the scope of protection of the present invention.

Claims

1. An anti-erosion castable for circulating fluidized bed boilers, characterized in that, The composition by weight is as follows: 25-35 parts fused white corundum, 15-23 parts corundum composite powder, 10-15 parts mullite particles, 10-15 parts silane-bonded silicon carbide, 15-18 parts modified chromium corundum, 6-8 parts binder, and 3-6 parts water.

2. The anti-erosion castable for circulating fluidized bed boilers according to claim 1, characterized in that, The preparation method of the modified chromium corundum includes: mixing TiO2 powder, chromium corundum and phenolic resin evenly, pressing into shape, drying, calcining and crushing to obtain the product.

3. The anti-erosion castable for circulating fluidized bed boilers according to claim 2, characterized in that, The mass ratio of TiO2 powder to chromium corundum is 1:5-6; the mass ratio of chromium corundum to phenolic resin is 1:0.1-0.

2.

4. The anti-erosion castable for circulating fluidized bed boilers according to claim 2, characterized in that, The drying temperature is 110 ℃, and the drying time is 5-6 h; the calcination is carried out in a nitrogen atmosphere; the calcination procedure is as follows: the temperature is increased to 450-500 ℃ at a heating rate of 2 ℃ / min, and held for 5-10 h, then increased to 750-800 ℃ at a heating rate of 4 ℃ / min, and held for 5-10 h, and finally increased to 1350-1420 ℃ at a heating rate of 3 ℃ / min, and held for 5-6 h, thus obtaining the product.

5. The anti-erosion castable for circulating fluidized bed boilers according to claim 1, characterized in that, The preparation method of the corundum composite powder includes: mixing corundum powder, TiO2 powder and TiN powder and then ball milling to obtain corundum mixed powder; melting the corundum mixed powder in an electric arc furnace; cooling and crystallizing; and then pulverizing to obtain the final product.

6. The anti-erosion castable for circulating fluidized bed boilers according to claim 5, characterized in that, The mass ratio of corundum powder to TiO2 powder is 10:0.9-1; the mass ratio of corundum powder to TiN powder is 10:0.4-0.5; and the temperature of the electric arc furnace is 2000-2500 ℃.

7. The anti-erosion castable for circulating fluidized bed boilers according to claim 1, characterized in that, The content of Al2O3 in the fused white fused alumina is ≥99%, the content of Fe2O3 is ≤0.3%, and the particle size of the fused white fused alumina is 1-3 mm; the particle size of the mullite particles is 0.5-1 mm; and the particle size of the silon-bonded silicon carbide is 1-50 μm.

8. The anti-erosion castable for circulating fluidized bed boilers according to claim 1, characterized in that, The modified chromium corundum comprises, by mass percentage: 10-20% aggregate with a particle size of 3-5 mm, 20-40% aggregate with a particle size of 1-3 mm, 10-20% aggregate with a particle size of 0.088-1 mm, and the remainder being fine powder with a particle size <0.088 mm; the particle size of the corundum composite powder is <0.044 mm.

9. The anti-erosion castable for circulating fluidized bed boilers according to claim 1, characterized in that, The binder is silica sol and calcium aluminate cement, wherein the mass of calcium aluminate cement is 55-78% of the mass of the binder, and the mass of silica sol is 22-45% of the mass of the binder.

10. A method for preparing an anti-erosion castable for a circulating fluidized bed boiler as described in any one of claims 1-9, characterized in that, The process includes the following steps: After mixing the prescribed amounts of fused white corundum, corundum composite powder, mullite particles, silane-bonded silicon carbide, and modified chromium corundum evenly, add the prescribed amounts of binder and water and mix evenly. Then, vibrate to form the mixture, cure at room temperature for 12-24 hours, and then keep it at 110 ℃ for 12-24 hours to obtain the final product.

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