A high-radiation coating and spraying process for spraying the lining of a petroleum and petrochemical heating furnace

Abstract

The invention discloses a high-radiation coating for spraying a lining of a petroleum and petrochemical heating furnace and a spraying process. The coating comprises raw materials in the following proportions: 5-6% zirconium oxide, 27-27.5% small-particle silica sol, 14-15% silicon carbide, 8.1% chromium oxide, 27-28% brown corundum, 8-8.5% potassium dihydrogen phosphate, 10-11% calcium carbonate and 1-1.5% cobalt oxide, wherein the content of aluminum oxide in the brown corundum is not less than 95%. The high-radiation coating for spraying a lining of a petroleum and petrochemical heating furnace and the spraying process have high refractoriness and strong stability when used, are not affected by acid, alkali and salt environments, and the coating can effectively penetrate, has strong adhesion ability, is durable for a long time and meets use requirements.

Description

Technical Field

[0001] The invention relates to the technical field of high-radiation coatings, and in particular to a high-radiation coating and a spraying process for spraying a lining of a petroleum and petrochemical heating furnace. Background Art

[0002] Heating furnace coatings can be used as refractory materials on the heat-absorbing surfaces of various industrial furnaces. By using the high absorption rate and high emissivity of the coating to thermal radiation, the high-temperature furnace lining can absorb the heat of the furnace flame, improve the heat exchange conditions of the furnace, reduce the heat dissipation of the furnace body, and increase the thermal efficiency of energy utilization. At the same time, it has a good protective effect on the furnace matrix material, prolongs the service life of the furnace, and reduces the maintenance workload. In addition, by strengthening the radiation heat transfer of the furnace, it can also improve the uniformity of the temperature field in the furnace and the heating quality of the heated object.

[0003] The Chinese invention patent with announcement number CN103525142B discloses a heat radiation coating for heating furnaces, including base material, additives, adhesive, plasticizer and solvent. The base material and additives are selected from five or all of zinc aluminum spinel powder, manganese aluminum spinel powder, ilmenite powder, boron carbide, iron oxide, and desiliconized zirconium powder; the adhesive is composed of liquid aluminum dihydrogen phosphate and liquid magnesium dihydrogen phosphate. The weight percentage of the base material and additives is 6%-75%, the weight percentage of the adhesive is 5%-29%, the weight percentage of the plasticizer is 0.5%-3%, and the balance is solvent; the technical problems of weak thermal shock resistance and weak adhesion are solved, and the thermal efficiency of energy utilization can be improved at the same time.

[0004] However, the emissivity of the above-mentioned high-radiation coating is unstable during use, and the coating particles cannot be suspended in the air, which will result in poor penetration after spraying. In a high-temperature thermal radiation environment, it will affect its adhesion ability and shorten its service life. If it is to be used again, the furnace will need to be stopped for spraying again, which will affect production and increase costs. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems and provide a high-radiation coating and spraying process for spraying the lining of a petroleum and petrochemical heating furnace, which has high refractoriness and strong stability during use and is not affected by acid, alkali or salt environments. In addition, the coating can effectively penetrate, has strong adhesion and is long-lasting.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present invention is: a high-radiation coating for spraying the lining of a petroleum and petrochemical heating furnace, comprising raw materials in the following proportions: 5-6% zirconium oxide, 27-27.5% small-particle silica sol, 14-15% silicon carbide, 8.1% chromium oxide, 27-28% brown corundum, 8-8.5% potassium dihydrogen phosphate, 10-11% calcium carbonate and 1-1.5% cobalt oxide, with the balance being silica sol.

[0007] Preferably, the zirconium oxide comprises 5.6%, small-particle silica sol 27.2%, silicon carbide 4.5%, chromium oxide 8.1%, brown corundum 27.6%, potassium dihydrogen phosphate 8.3%, calcium carbonate 10.4% and cobalt oxide 1.3%, and the balance is silica sol.

[0008] Preferably, the aluminum oxide content in the brown corundum is not less than 95%.

[0009] A spraying process for high-radiation coating of a petroleum and petrochemical heating furnace lining comprises the following steps: S1: removing floating dust on the lining surface; S2: removing slag on the lining; S3: filling and leveling the lining surface; S4: pre-treating the inner lining surface; S5: spraying thin coating; S6: spraying thick coating.

[0010] Preferably, in step S4, a treatment liquid is sprayed onto the surface of the lining for pretreatment, wherein the treatment liquid is a glue-water mixture with a ratio of 60:1.

[0011] Preferably, in steps S5 and S6, the thin material and the thick material are sprayed 4-6 times respectively.

[0012] Preferably, the volume of the water solvent in the thin material is 1.5 times the volume of the water solvent in the thick material.

[0013] Preferably, in step S6, the overall coating thickness after the thick material is sprayed is not less than 2 mm.

[0014] Compared with the prior art, the high-radiation coating and spraying process for spraying the lining of a petroleum and petrochemical heating furnace disclosed in the present invention have the following beneficial effects: 1. Improving the emissivity of the lining of the petroleum and petrochemical heating furnace and increasing the effective radiation of the lining to the furnace; 2. High refractoriness, which can effectively protect the lining of the petroleum and petrochemical heating furnace, resist corrosion, acid and alkali combustion, and optimize the construction process of the high-radiation coating lining; 3. The coating can effectively penetrate and adhere well during spraying, and is long-lasting and durable. DETAILED DESCRIPTION

[0015] A high-radiation coating for spraying the lining of a petroleum and petrochemical heating furnace comprises raw materials in the following proportions: 5-6% zirconium oxide (ZrO2), 27-27.5% small-particle silica sol (2SiO2.5H2O), 14-15% silicon carbide (SiC), 8.1% chromium oxide (Cr2O3), 27-28% brown corundum (AL2O3≥95%), 8-8.5% potassium dihydrogen phosphate (KH2PO4), 10-11% calcium carbonate (CaCO3) and 1-1.5% cobalt oxide (CoO), with the remainder being silica sol, wherein the aluminum oxide content in the brown corundum is not less than 95%.

[0016] Embodiment 1: The high-radiation coating comprises raw materials in the following proportions: 5% zirconium oxide (ZrO2), 27% small-particle silica sol (2SiO2.5H2O), 114% silicon carbide (SiC), 8.1% chromium oxide (Cr2O3), 27% brown corundum (AL2O3≥95%), 8% potassium dihydrogen phosphate (KH2PO4), 10% calcium carbonate (CaCO3) and 1% cobalt oxide (CoO), with the remainder being silica sol.

[0017] In this embodiment, the specific performance parameters are as follows:

[0018]

[0019] In this embodiment, the refractoriness, emissivity, adhesion and anti-seismic performance are all satisfactory for use, but in acid, alkali and salt environments, damage occurs to varying degrees, which will directly affect the service life.

[0020] Embodiment 2: The high-radiation coating comprises raw materials in the following proportions: 5.6% zirconium oxide (ZrO2), 27.2% small-particle silica sol (2SiO2.5H2O), 4.5% silicon carbide (SiC), 8.1% chromium oxide (Cr2O3), 27.6% brown corundum (AL2O3≥95%), 8.3% potassium dihydrogen phosphate (KH2PO4), 10.4% calcium carbonate (CaCO3) and 1.3% cobalt oxide (CoO), with the remainder being silica sol.

[0021] In this embodiment, the specific performance parameters are as follows:

[0022] project Numeric project Numeric Bulk density g / cm3 1.6-1.8 ViscosityPa.s Spraying<20 Refractoriness ℃ ≥1800 Adhesion(grade) 1～2 Emissivity ε 0.92 Acid resistance No change after 3 days of immersion in 40% H2SO4 Expansion coefficient <![CDATA[5.72 ×10 -6 ]]> Alkali resistance No change after 3-day immersion in 20% NaOH Shock resistance ≥15 times Salt tolerance No change after 3-day immersion in 10% NaCl Anti-aging properties Coating 1200℃, ε≥0.89 Thermal conductivity W / mk 27.6 Re-firing linear shrinkage (%, 1200℃) 1.7 Service life (years) 3-10

[0023] This embodiment is a preferred embodiment of the present invention, and its refractoriness, adhesion, emissivity, acid, alkali, salt resistance and service life all achieve the best effects; the whole is stirred and refined through a powder sieve to present a suspended state, and on the premise of ensuring the emissivity, it can penetrate into the refractory matrix and combine with the refractory penetration state; at the same time, the construction method of combining auxiliary thin materials and thick materials ensures that the coating does not fall off after spraying, and can make the coating better penetrate into the lining of the petroleum and petrochemical heating furnace, and be squeezed and combined with the surface of the lining, and the performance is long-lasting and durable.

[0024] Example 3: High-radiation coating, including raw materials in the following proportions, zirconium oxide (ZrO2) 6%, small-particle silica sol (2SiO2.5H2O) 27.5%, silicon carbide (SiC) 15%, chromium oxide (Cr2O3) 8.1%, brown corundum (AL2O3≥95%) 28%, potassium dihydrogen phosphate (KH2PO4) 8.5%, calcium carbonate (CaCO3) 11% and cobalt oxide (CoO) 1.5%, with the remainder being silica sol.

[0025] In this embodiment, the specific performance parameters are as follows:

[0026] project Numeric project Numeric Bulk density g / cm3 1.8-2.2 ViscosityPa.s Spraying<20 Refractoriness ℃ ≥1800 Adhesion(grade) 1 Emissivity ε 0.92 Acid resistance No change after 3-day immersion in 40% H2SO4 Expansion coefficient <![CDATA[5.72 ×10 -6 ]]> Alkali resistance No change after 3-day immersion in 20% NaOH Shock resistance ≥15 times Salt tolerance No change after 3-day immersion in 10% NaCl Anti-aging properties Coating 1200℃, ε≥0.89 Thermal conductivity W / mk 27.6 Re-firing linear shrinkage (%, 1200℃) 1.7 Service life (years) 2-8

[0027] The coating of this embodiment has good acid, alkali and salt resistance, but poor overall adhesion and service life. It is not durable during use and is easy to fall off in high temperature environments.

[0028] Based on the above three embodiments, the preparation method of the high-radiation coating is as follows: firstly, the raw materials are ground into powder, wherein the particle size of zirconium oxide (ZrO2), small-particle silica sol (2SiO2.5H2O), silicon carbide (SiC) and chromium oxide (Cr2O3) is less than 500nm, the particle size of brown corundum and potassium dihydrogen phosphate (KH2PO4) is less than 0.01mm, and the particle size of calcium carbonate (CaCO3) and cobalt oxide (CoO) is less than 0.2mm. After the raw materials are ground and refined, they are mixed with silica sol. At this time, the raw material powder will be in a suspended state in the silica sol, which reduces the internal stress of the coating and increases the adhesion ability of the coating. When spraying, the suspended glue-containing particles can be sprayed onto the surface of the furnace lining. After spraying, the adhesion is strong, the coating is easy to penetrate and durable.

[0029] The present invention also discloses a spraying process of a high-radiation coating for spraying on the lining of a petroleum and petrochemical heating furnace, comprising the following steps: S1: removing floating dust on the surface of the lining, removing and collecting the floating dust on the surface of the lining by auxiliary tools such as a brush vacuum cleaner; S2: removing slag on the lining, removing slag on the surface of the lining by tools such as a hard steel brush and a flat shovel; S3: after the slag is removed, cracks and fissures on the surface of the lining will be directly exposed to the outside, at this time, the surface of the lining is repaired and leveled by a repair material, wherein the repair material is a mixture of fused quartz, borosilicate glass, brown corundum powder, fluororesin and silicone solution, and the ratio is 1:1.5:4:2:6; after mixing according to the ratio, stirring continuously until the repair material is in a paste state, brushing it to the cracks and fissures, and smoothing the surface of the lining after filling the seams to avoid potholes and protrusions; S4: The surface of the lining is pretreated by spraying a treatment liquid, wherein the treatment liquid is a glue-water mixture in a ratio of 60:1. After pretreatment, the surface tension of the lining will be improved, and the bonding ability between the lining and the coating will be further increased; S5: Spraying of thin coating (one spraying), spraying the above-mentioned high-radiation coating onto the pretreated surface of the lining, spraying 4-6 times, so that the coating can penetrate the surface of the lining; S6: Spraying of thick coating (secondary spraying), then spraying the thick high-radiation coating onto the thin material in S5, spraying 4-6 times, and the overall coating thickness after spraying the thick material is not less than 2mm, further improving the service life.

[0030] The volume of the water solvent in the thin material (the thin material in S5) is 1.5 times the volume of the water solvent in the thick material (the thick material in S6).

[0031] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A high-radiation coating for spraying the lining of a petroleum and petrochemical heating furnace, characterized in that: The invention comprises raw materials in the following proportions: 5.6% zirconium oxide, 27.2% small-particle silica sol, 4.5% silicon carbide, 8.1% chromium oxide, 27.6% brown corundum, 8.3% potassium dihydrogen phosphate, 10.4% calcium carbonate and 1.3% cobalt oxide, with the remainder being silica sol. The aluminum oxide content in the brown corundum is not less than 95%.

2. A spraying process for high-radiation coating for petroleum and petrochemical heating furnace lining according to claim 1, characterized in that: The method comprises the following steps: S1: removing floating dust on the surface of the furnace lining; S2: removing slag on the furnace lining; S3: filling and leveling the surface of the furnace lining; S4: pre-treating the surface of the inner lining; S5: spraying a thin coating; S6: spraying a thick coating.

3. The spraying process of the high-radiation coating for the lining of the petroleum and petrochemical heating furnace according to claim 2 is characterized in that: In the step S4, the treatment liquid is sprayed onto the surface of the lining for pretreatment, wherein the treatment liquid is a glue-water mixture with a ratio of 60:

1.

4. The spraying process of the high-radiation coating for the lining of the petroleum and petrochemical heating furnace according to claim 3 is characterized in that: In the steps S5 and S6, the thin material and the thick material are sprayed 4-6 times respectively.

5. The spraying process of high-radiation coating for petroleum and petrochemical heating furnace lining according to claim 4 is characterized in that: The volume of the water solvent in the thin material is 1.5 times the volume of the water solvent in the thick material.

6. The spraying process of high-radiation coating for petroleum and petrochemical heating furnace lining according to claim 5 is characterized in that: In the step S6, the overall coating thickness after the thick material is sprayed is not less than 2 mm.

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