Anti-corrosion coating for garbage power generation high-temperature heating surface as well as preparation method and application of anti-corrosion coating

Abstract

The invention provides an anticorrosive coating for a high-temperature heating surface of garbage power generation and a preparation method and application of the anticorrosive coating. The anticorrosive coating is prepared by selecting high-temperature-resistant inorganic resin as a film-forming agent and modified magnesium oxide as a curing agent and matching with rare-earth metal oxide, ceramic powder, flaky metal powder and other auxiliaries; the curing agent is used for coating and modifying magnesium oxide by adopting a sol-gel method, so that the activation period of the coating is prolonged; the flaky metal powder is infiltrated and coated with polysiloxane, the hydrophobic property and low surface tension of the polysiloxane drive the flaky metal powder to migrate in a liquid phase in the surface drying process of the coating, the flaky metal powder is arranged on the surface layer of the coating to form a labyrinth structure, and the polysiloxane forms an oily hydrophobic shielding layer on the outermost layer; the coating has low-temperature curing performance, excellent surface drying and heat and humidity resistance and excellent high-temperature resistance and corrosion resistance, and due to the performance, the coating can achieve sintering and long-period protection effects on the high-temperature heating surfaces of the first flue and the second flue of the waste incineration power generation boiler.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature protective coatings, and specifically relates to an anti-corrosion coating for high-temperature heating surfaces of waste-to-energy power generation, and a preparation method and application thereof. Background Art

[0002] Waste-to-energy (WTE) is a major development in clean energy, utilizing waste for pollution-free resource processing, protecting the environment while improving economic efficiency. However, high-temperature furnace corrosion is a common problem in WTE power plants. This is due to the low operating parameters of the units, with the front-end tube wall operating temperature typically between 250°C and 350°C. High-temperature protective coatings form slowly within this temperature range, and the high water vapor content in the flue gas during startup makes the coating susceptible to dissolution and damage during the coating sintering phase.

[0003] In order to improve the low-temperature curing and surface-drying moisture and heat resistance of the ceramic coating, the present invention innovatively uses sol-gel modified calcined magnesium oxide as a curing agent, achieving a long activation cycle while allowing the coating to be sintered at a low temperature of 180°C to form a film. At the same time, in order to improve the surface-drying moisture and heat resistance of the coating and prevent water vapor in the flue gas from damaging the coating, the present invention uses modified polysiloxane to coat the flaky metal powder. During the surface drying process of the coating, the polysiloxane-modified flaky metal powder migrates to the surface of the coating, providing surface-drying hydrophobic properties and a flaky shielding effect. The flaky metal powder is arranged in a superimposed manner with the directional movement of the polysiloxane, forming an oil-in-water microscopic double coating structure on the surface. The present invention improves the low-temperature film-forming effect of the high-temperature resistant inorganic coating, while overcoming the initial water resistance problem of the coating, and improving the film-forming effect and density of the coating. The low surface tension effect reduces the adhesion of dust on the high-temperature heated surface and improves the heat exchange efficiency of the unit. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide an anti-corrosion coating for high-temperature heating surfaces of waste-to-energy power generation, and its preparation method and application. The coating can reduce the sintering film-forming temperature, has good surface dry moisture and heat resistance, and has excellent anti-corrosion shielding effect and anti-fouling performance.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] 1. An anti-corrosion coating for high-temperature heating surfaces in waste-to-energy plants, characterized in that the coating comprises the following raw materials in parts by weight:

[0007] The invention discloses an anti-corrosion coating for high-temperature heating surfaces of garbage power generation, comprising the following raw materials in parts by weight: 20-50 parts of high-temperature resistant inorganic resin, 0.5-1.5 parts of modified magnesium oxide, 5-15 parts of rare earth oxide, 20-40 parts of ceramic powder, 3-5 parts of flaky metal powder, 1-5 parts of polysiloxane, 0.5-3 parts of leveling agent, 3-10 parts of passivating agent, 3-5 parts of butyl ether, and 0-20 parts of deionized water.

[0008] The high temperature resistant inorganic resin is liquid aluminum dihydrogen phosphate with a mass solid content of 45-52% and a resin Al / P molar ratio

[0009] =0.25-0.28.

[0010] The rare earth oxide is one of cerium oxide and yttrium oxide or a mixture of the two, and the powder particle size D50 is less than 20 μm.

[0011] The ceramic powder is at least one of boron nitride, silicon nitride and chromium oxide green. Preferably, boron nitride is a hexagonal flake structure, silicon nitride and chromium oxide green are spherical powders, and the powder particle size D50 is less than 40 μm.

[0012] The flaky metal powder is stearic acid-coated titanium powder, the powder particle size D50 is less than 25 μm, and the mass content of stearic acid is less than 5%.

[0013] The polysiloxane is Wacker 5350 modified polysiloxane.

[0014] The passivating agent is sodium molybdate.

[0015] The leveling agent is talcum powder with a particle size of D50 less than 40 μm.

[0016] The nano silica sol is neutral or weakly alkaline silica sol.

[0017] Preferably, the anti-corrosion coating for high-temperature heating surfaces of waste-to-energy power generation comprises the following raw materials in parts by weight: 30-40 parts of high-temperature resistant inorganic resin, 0.5-1 part of modified magnesium oxide, 5-10 parts of rare earth oxide, 20-40 parts of ceramic powder, 3-5 parts of flaky metal powder, 1-5 parts of polysiloxane, 0.5-3 parts of leveling agent, 5 parts of passivator, 3 parts of butyl ether, and 10-20 parts of deionized water.

[0018] The modified magnesium oxide preparation method comprises the following steps:

[0019] (1) Calcined magnesium oxide was added to deionized water under high-speed stirring, and dispersed at high speed for 30-40 minutes under circulating water cooling to prepare a 50% wt dispersion slurry;

[0020] (2) Take 100-150 ml of nano-silica sol, dilute it with an equal volume of deionized water, the colloid solid content is 20-30 wt%, the average particle size is 10-40 nm, and stir and disperse it under ultrasonic conditions for 5-10 minutes;

[0021] (3) slowly adding the slurry of step (1) into the dispersion of step (2) under stirring, and stirring in an ice-water bath for 1-2 hours;

[0022] (4) The slurry in step (3) is filtered through a 200-mesh filter, and the filtrate is rinsed with deionized water 1-2 times. After washing, the solid material is freeze-dried in a vacuum to remove moisture, and the powder after drying is modified magnesium oxide.

[0023] Another object of the present invention is to provide a method for preparing an anti-corrosion coating for a high-temperature heating surface of a waste-to-energy power plant, comprising the following steps:

[0024] (1) Prepare materials: 30-40 parts of high temperature resistant inorganic resin, 0.5-1 part of modified magnesium oxide, 5-10 parts of rare earth oxide, 20-40 parts of ceramic powder, 3-5 parts of flaky metal powder, 1-5 parts of polysiloxane, 0.5-3 parts of leveling agent, 5 parts of passivating agent, 3 parts of butyl ether, and 10-20 parts of deionized water.

[0025] (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse it for 10-20 minutes to form a uniform dispersion;

[0026] (3) Diluting polysiloxane with butyl ether, adding flake metal powder, stirring evenly with a glass rod, and then placing it in ultrasonic dispersion for 15-20 minutes to obtain a mixed solution;

[0027] (4) adding the mixed solution of step (3), rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 400-600 rad, and after the powder is fully wetted, dispersing at a high speed of 1000-1500 rad for 30 minutes under a circulating water cooling state to obtain a slurry;

[0028] (5) adding a leveling agent to the slurry prepared in step (4), dispersing the mixture at 500-600 rad for 10 min, testing the slurry fineness to ensure that it is qualified, adjusting the viscosity with the remaining deionized water, and filtering the mixture to obtain the coating component A;

[0029] (6) The modified magnesium oxide powder is the coating B component and can be dispersed by machine on site when used.

[0030] Another object of the present invention is to provide a method for applying an anti-corrosion coating to a high-temperature heating surface of a waste-to-energy power plant, comprising the following steps:

[0031] (1) Take a 20G metal substrate and use quartz sand with a particle size of 10-30 mesh to sandblast the substrate at a pressure of 0.6-0.8 MPa and an angle of 30-60°; the construction environment is controlled at a temperature of 5-35°C and a relative humidity of 0-85%. The sandblasting requires the substrate to reach Sa3.0 cleanliness and a surface roughness Rz>40μm;

[0032] (2) Add component B to component A while stirring, and bend the mixture at 500 rad for 5-10 minutes. The coating is sprayed. Before spraying, the surface of the sandblasted substrate is soot-blown. The prepared coating is stirred evenly and adjusted to a suitable viscosity with water. Air spraying is used, and the air inlet pressure is controlled at 0.3-0.5 MPa. The distance between the spray gun and the coated surface is 20-40 cm, and the spray width is 20-40 cm. The spray gun is at an angle of 45-90° to the coated surface.

[0033] (3) Spraying needs to be completed in multiple times, and the total spray film thickness is controlled at 300±20μm. The surface must be fully dried between each spraying before the next spraying can be carried out. The wet film thickness of a single spraying is controlled within 150μm; after spraying is completed, let it stand for 4-6 hours to dry the surface. After the coating is completely dry, heat it from room temperature to 180℃ and keep it warm for 1-2 hours. The heating rate is controlled at 2-3℃ / min. After curing, the anti-corrosion coating is prepared.

[0034] Another object of the present invention is to provide an application of an anti-corrosion coating for high-temperature heating surfaces of waste-to-energy power generation. Applying it to the metal surfaces of the first and second flue water-cooled walls of a waste incineration power generation unit can prevent high-temperature corrosion, reduce contamination and coking of the high-temperature heating surfaces, and increase the service life of the pipe wall substrate.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention provides an anti-corrosion coating for high-temperature heating surfaces of waste-to-energy power generation, and its preparation method and application. The technical benefits include: (1) The magnesium oxide curing agent is modified by the sol-gel method, so that the phosphate high-temperature corrosion-resistant coating can be sintered and cured in a medium-low temperature environment, while ensuring that the coating has a suitable construction activation period. (2) The oily polysiloxane and stearic acid-modified flaky metal powder are similarly dissolved and coated and dispersed. During the surface drying process of the coating, the polysiloxane undergoes low surface tension migration in the water washing system, and the polysiloxane drives the flaky metal powder to migrate and arrange to the surface of the coating, eventually forming a dense coating structure with oily surface and watery bottom. (3) During the furnace start-up stage, the tube wall temperature is low and the coating has not been sintered. The high water vapor content in the flue gas will dissolve and destroy the ceramic coating. The low surface tension surface drying process of the surface oily polysiloxane will form a hydrophobic layer, which enhances the coating's resistance to moisture and heat and ensures that the coating is not destroyed during the sintering stage. (4) The low surface tension coating surface structure can reduce the contamination and coking of the high-temperature heating surface and improve the heat exchange efficiency of the high-temperature heating surface. DETAILED DESCRIPTION

[0037] To further understand the present invention, preferred embodiments of the present invention are described below with reference to the following examples. However, it should be understood that these examples are intended only to further illustrate the features and advantages of the present invention and are not intended to limit the scope of the present invention. All raw materials used in the present invention are not particularly limited in their sources and can be purchased commercially or prepared according to conventional methods known to those skilled in the art.

[0038] Example 1

[0039] Disclosed is an anti-corrosion coating for high-temperature heating surfaces of garbage-to-energy plants, comprising the following raw materials in parts by weight: 40 parts of high-temperature resistant inorganic resin, 1 part of modified magnesium oxide, 10 parts of rare earth oxide, 40 parts of ceramic powder, 5 parts of flaky metal powder, 5 parts of polysiloxane, 3 parts of leveling agent, 5 parts of passivator, 3 parts of butyl ether, and 20 parts of deionized water.

[0040] The high-temperature resistant inorganic resin is liquid aluminum dihydrogen phosphate with a mass solid content of 45% and a resin Al / P molar ratio of 0.25.

[0041] The rare earth oxide is cerium oxide, and the powder particle size D50 is less than 20 μm.

[0042] The ceramic powder is boron nitride, silicon nitride, and chromium oxide green powder in a mass ratio of 1:2:2, and the powder particle size D50 is less than 40 μm.

[0043] The flaky metal powder is stearic acid-coated titanium powder, the powder particle size D50 is less than 25 μm, and the mass content of stearic acid is less than 5%.

[0044] The polysiloxane is Wacker 5350 modified polysiloxane.

[0045] The passivating agent is sodium molybdate.

[0046] The leveling agent is talcum powder with a particle size of D50 less than 40 μm.

[0047] The nano silica sol is a neutral silica sol, and the colloidal particle size D50 is ≤20nm.

[0048] The modified magnesium oxide is prepared as follows:

[0049] (1) Calcined magnesium oxide was added to deionized water under high-speed stirring, and dispersed at high speed for 30 minutes under circulating water cooling to prepare a 50% wt dispersion slurry;

[0050] (2) Take 150 ml of nano-silica sol, dilute it with an equal volume of deionized water, and make the colloid solid content 25% and the average particle size 20 nm. Stir and disperse it under ultrasonic conditions for 5-10 minutes.

[0051] (3) slowly adding the slurry from step (1) to the dispersion from step (2) under stirring, and stirring in an ice-water bath for 1 h;

[0052] (4) The slurry in step (3) is filtered through a 200-mesh filter, and the filtrate is rinsed once with deionized water. After washing, the solid material is freeze-dried in a vacuum to remove moisture, and the powder after drying is modified magnesium oxide.

[0053] Example 2

[0054] Disclosed is an anti-corrosion coating for high-temperature heating surfaces of garbage-to-energy plants, comprising the following raw materials in parts by weight: 30 parts of high-temperature resistant inorganic resin, 0.5 parts of modified magnesium oxide, 10 parts of rare earth oxide, 30 parts of ceramic powder, 3 parts of flaky metal powder, 3 parts of polysiloxane, 1 part of leveling agent, 5 parts of passivator, 3 parts of butyl ether, and 10 parts of deionized water.

[0055] The high-temperature resistant inorganic resin is liquid aluminum dihydrogen phosphate, with a mass solid content of 45% and a resin Al / P molar ratio of 0.28.

[0056] The rare earth oxides are cerium oxide and yttrium oxide, the powder mass ratio is 1:1, and the powder particle size D50 is less than 20 μm.

[0057] The ceramic powder is boron nitride, silicon nitride, and chromium oxide green powder in a mass ratio of 1:1:3, and the powder particle size D50 is less than 40 μm.

[0058] The flaky metal powder is stearic acid-coated titanium powder, the powder particle size D50 is less than 25 μm, and the mass content of stearic acid is less than 5%.

[0059] The polysiloxane is Wacker 5350 modified polysiloxane.

[0060] The passivating agent is sodium molybdate.

[0061] The leveling agent is talcum powder with a particle size of D50 less than 40 μm.

[0062] The nano silica sol is a neutral silica sol, and the colloidal particle size D50 is ≤10nm.

[0063] The modified magnesium oxide is prepared as follows:

[0064] (1) Calcined magnesium oxide was added to deionized water under high-speed stirring, and dispersed at high speed for 30 minutes under circulating water cooling to prepare a 50% wt dispersion slurry;

[0065] (2) Take 150 ml of nano-silica sol and dilute it with an equal volume of deionized water to a colloidal solid content of 20% and an average particle size of 10 nm. Stir and disperse it under ultrasonic conditions for 10 min.

[0066] (3) slowly adding the slurry from step (1) to the dispersion from step (2) under stirring, and stirring in an ice-water bath for 1 h;

[0067] (4) The slurry in step (3) is filtered through a 200-mesh filter, and the filtrate is rinsed twice with deionized water. After washing, the solid material is freeze-dried in a vacuum to remove moisture, and the powder after drying is modified magnesium oxide.

[0068] Example 3

[0069] Disclosed is an anti-corrosion coating for high-temperature heating surfaces of garbage-to-energy plants, comprising the following raw materials in parts by weight: 30 parts of high-temperature resistant inorganic resin, 1 part of modified magnesium oxide, 5 parts of rare earth oxide, 20 parts of ceramic powder, 5 parts of flaky metal powder, 5 parts of polysiloxane, 0.5 parts of leveling agent, 5 parts of passivator, 3 parts of butyl ether, and 20 parts of deionized water.

[0070] The high-temperature resistant inorganic resin is liquid aluminum dihydrogen phosphate, with a mass solid content of 48% and a resin Al / P molar ratio of 0.27.

[0071] The rare earth oxide is yttrium oxide, and the powder particle size D50 is less than 20 μm.

[0072] The ceramic powder is boron nitride and chromium oxide green powder in a mass ratio of 1:4, and the powder particle size D50 is less than 40 μm.

[0073] The flaky metal powder is stearic acid-coated titanium powder, the powder particle size D50 is less than 25 μm, and the mass content of stearic acid is less than 5%.

[0074] The polysiloxane is Wacker 5350 modified polysiloxane.

[0075] The passivating agent is sodium molybdate.

[0076] The leveling agent is talcum powder with a particle size of D50 less than 40 μm.

[0077] The nano silica sol is a weakly alkaline silica sol with a pH value of 8-9 and a colloidal particle size D50≤40nm.

[0078] The modified magnesium oxide is prepared as follows:

[0079] (1) Calcined magnesium oxide was added to deionized water under high-speed stirring, and dispersed at high speed for 40 minutes under circulating water cooling to prepare a 50% wt dispersion slurry;

[0080] (2) Take 100 ml of nano-silica sol and dilute it with an equal volume of deionized water to a colloidal solid content of 30% and an average particle size of 40 nm. Stir and disperse it under ultrasonic conditions for 10 min.

[0081] (3) slowly adding the slurry from step (1) to the dispersion from step (2) under stirring, and stirring in an ice-water bath for 1 h;

[0082] (4) The slurry in step (3) is filtered through a 200-mesh filter, and the filtrate is rinsed twice with deionized water. After washing, the solid material is freeze-dried in a vacuum to remove moisture, and the powder after drying is modified magnesium oxide.

[0083] Example 4

[0084] Disclosed is an anti-corrosion coating for high-temperature heating surfaces of garbage-to-energy plants, comprising the following raw materials in parts by weight: 35 parts of high-temperature resistant inorganic resin, 0.8 parts of modified magnesium oxide, 5 parts of rare earth oxide, 35 parts of ceramic powder, 3 parts of flaky metal powder, 1 part of polysiloxane, 2 parts of leveling agent, 5 parts of passivator, 3 parts of butyl ether, and 20 parts of deionized water.

[0085] The high-temperature resistant inorganic resin is liquid aluminum dihydrogen phosphate, with a mass solid content of 52% and a resin Al / P molar ratio of 0.28.

[0086] The rare earth oxide is cerium oxide, and the powder particle size D50 is less than 20 μm.

[0087] The ceramic powder is boron nitride and chromium oxide green powder in a mass ratio of 2:3, and the powder particle size D50 is less than 40 μm.

[0088] The flaky metal powder is stearic acid-coated titanium powder, the powder particle size D50 is less than 25 μm, and the mass content of stearic acid is less than 5%.

[0089] The polysiloxane is Wacker 5350 modified polysiloxane.

[0090] The passivating agent is sodium molybdate.

[0091] The leveling agent is talcum powder with a particle size of D50 less than 40 μm.

[0092] The nano silica sol is a neutral silica sol, and the colloidal particle size is ≤20nm.

[0093] The modified magnesium oxide is prepared as follows:

[0094] (1) Calcined magnesium oxide was added to deionized water under high-speed stirring, and dispersed at high speed for 30 minutes under circulating water cooling to prepare a 50% wt dispersion slurry;

[0095] (2) Take 150 ml of nano-silica sol and dilute it with an equal volume of deionized water to a colloidal solid content of 25% and an average particle size of 20 nm. Stir and disperse it under ultrasonic conditions for 10 min.

[0096] (3) slowly adding the slurry from step (1) to the dispersion from step (2) under stirring, and stirring for 2 h in an ice-water bath;

[0097] (4) The slurry in step (3) is filtered through a 200-mesh filter, and the filtrate is rinsed twice with deionized water. After washing, the solid material is freeze-dried in a vacuum to remove moisture, and the powder after drying is modified magnesium oxide.

[0098] A comparative example was prepared with reference to Example 1 to test the effect of the compounding of each component on the coating performance. The details are as follows:

[0099] 1. Comparative Example 1

[0100] Compared with Example 1, the magnesium oxide was not modified and the same mass of calcined magnesium oxide was directly added. The other raw materials were exactly the same as those in Example 1.

[0101] 2. Comparative Example 2

[0102] Compared with Example 1, modified magnesium oxide was not added, and the other raw materials were exactly the same as those in Example 1.

[0103] 3. Comparative Example 3

[0104] Compared with Example 1, no polysiloxane was added, and the other raw materials were exactly the same as those in Example 1.

[0105] 4. Comparative Example 4

[0106] Compared with Example 1, no flaky metal powder is added, and the remaining raw materials are completely the same as those in Example 1.

[0107] 5. Comparative Example 5

[0108] Compared with Example 1, no polysiloxane-modified sheet metal is added, and the remaining raw materials are completely the same as those in Example 1.

[0109] The anti-corrosion coating for the high-temperature heating surface of the waste-to-energy power generation system described in Examples 1-4 was prepared according to the following preparation method, including the following steps:

[0110] (1) Preparing materials according to the formula of the anti-corrosion coating for the high-temperature heating surface of waste-to-energy power generation described in Examples 1-4;

[0111] (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse for 15 minutes to form a uniform dispersion;

[0112] (3) Diluting polysiloxane with butyl ether, adding flake metal powder, stirring evenly with a glass rod, and then placing it in ultrasonic dispersion for 20 minutes to obtain a mixed solution;

[0113] (4) adding the mixed solution of step (3), rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 500 rad, and after the powder is fully wetted, dispersing at a high speed of 1500 rad for 30 minutes under a circulating water cooling state to obtain a slurry;

[0114] (5) adding a leveling agent to the slurry prepared in step (4), dispersing the slurry at 500 rad for 10 min, testing the slurry fineness to be ≤40 μm, adjusting the viscosity with the remaining deionized water, and filtering to obtain the coating component A;

[0115] (6) Add the modified magnesium oxide powder component B to component A while stirring, and stir and disperse for 5 minutes.

[0116] The anti-corrosion coating for the high-temperature heating surface of the waste-to-energy power generation method described in Comparative Example 1 was prepared according to the following preparation method, including the following steps:

[0117] (1) preparing materials according to the formula of the anti-corrosion coating for the high-temperature heating surface of waste-to-energy power generation described in Comparative Example 1;

[0118] (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse for 15 minutes to form a uniform dispersion;

[0119] (3) Diluting polysiloxane with butyl ether, adding flake metal powder, stirring evenly with a glass rod, and then placing it in ultrasonic dispersion for 20 minutes to obtain a mixed solution;

[0120] (4) adding the mixed solution of step (3), rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 500 rad, and after the powder is fully wetted, dispersing at a high speed of 1500 rad for 30 minutes under a circulating water cooling state to obtain a slurry;

[0121] (5) adding a leveling agent to the slurry prepared in step (4), dispersing the slurry at 500 rad for 10 min, testing the slurry fineness to be ≤40 μm, adjusting the viscosity with the remaining deionized water, and filtering to obtain the coating component A;

[0122] (6) Add the calcined magnesium oxide powder component B to component A while stirring, and stir and disperse for 5 minutes.

[0123] The anti-corrosion coating for the high-temperature heating surface of the waste-to-energy power generation system described in Comparative Example 2 was prepared according to the following preparation method, including the following steps:

[0124] (1) Preparing materials according to the formula of the anti-corrosion coating for the high-temperature heating surface of waste-to-energy power generation described in Comparative Example 2;

[0125] (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse for 15 minutes to form a uniform dispersion;

[0126] (3) Diluting polysiloxane with butyl ether, adding flake metal powder, stirring evenly with a glass rod, and then placing it in ultrasonic dispersion for 20 minutes to obtain a mixed solution;

[0127] (4) adding the mixed solution of step (3), rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 500 rad, and after the powder is fully wetted, dispersing at a high speed of 1500 rad for 30 minutes under a circulating water cooling state to obtain a slurry;

[0128] (5) adding a leveling agent to the slurry prepared in step (4), dispersing the slurry at 500 rad for 10 min, testing the slurry fineness to be ≤40 μm, adjusting the viscosity with the remaining deionized water, and filtering to obtain the coating component A;

[0129] (6) Stir and disperse component A for 5 minutes.

[0130] The anti-corrosion coating for the high-temperature heating surface of the waste-to-energy power generation system described in Comparative Example 3 was prepared according to the following preparation method, including the following steps:

[0131] (1) preparing materials according to the formula of the anti-corrosion coating for the high-temperature heating surface of waste-to-energy power generation described in Comparative Example 3;

[0132] (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse for 15 minutes to form a uniform dispersion;

[0133] (3) adding flaky metal powder to the butyl ether solution, stirring evenly with a glass rod, and then placing it in ultrasonic dispersion for 20 minutes to obtain a mixed solution;

[0134] (4) adding the mixed solution of step (3), rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 500 rad, and after the powder is fully wetted, dispersing at a high speed of 1500 rad for 30 minutes under a circulating water cooling state to obtain a slurry;

[0135] (5) adding a leveling agent to the slurry prepared in step (4), dispersing the slurry at 500 rad for 10 min, testing the slurry fineness to be ≤40 μm, adjusting the viscosity with the remaining deionized water, and filtering to obtain the coating component A;

[0136] (6) Add the modified magnesium oxide powder component B to component A while stirring, and stir and disperse for 5 minutes.

[0137] The anti-corrosion coating for the high-temperature heating surface of the waste-to-energy power generation system described in Comparative Example 4 was prepared according to the following preparation method, including the following steps:

[0138] (1) Preparing materials according to the formula of the anti-corrosion coating for the high-temperature heating surface of waste-to-energy power generation described in Comparative Example 4;

[0139] (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse for 15 minutes to form a uniform dispersion;

[0140] (3) Dilute polysiloxane with butyl ether, stir evenly with a glass rod, and then ultrasonically disperse for 20 minutes to obtain a mixed solution;

[0141] (4) adding the mixed solution of step (3), rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 500 rad, and after the powder is fully wetted, dispersing at a high speed of 1500 rad for 30 minutes under a circulating water cooling state to obtain a slurry;

[0142] (5) adding a leveling agent to the slurry prepared in step (4), dispersing the slurry at 500 rad for 10 min, testing the slurry fineness to be ≤40 μm, adjusting the viscosity with the remaining deionized water, and filtering to obtain the coating component A;

[0143] (6) Add the modified magnesium oxide powder component B to component A while stirring, and stir and disperse for 5 minutes.

[0144] The anti-corrosion coating for the high-temperature heating surface of the waste-to-energy power generation method described in Comparative Example 5 was prepared according to the following preparation method, including the following steps:

[0145] (1) Preparing materials according to the formula of the anti-corrosion coating for the high-temperature heating surface of waste-to-energy power generation described in Comparative Example 5;

[0146] (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse for 15 minutes to form a uniform dispersion;

[0147] (3) adding rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 500 rad, and after the powder is fully wetted, dispersing at a high speed of 1500 rad for 30 minutes under a circulating water cooling state to obtain a mixed solution;

[0148] (4) adding a leveling agent to the slurry prepared in step (3), dispersing the slurry at 500 rad for 10 min, testing the slurry fineness to be ≤40 μm, adjusting the viscosity with the remaining deionized water, and filtering to obtain the coating component A;

[0149] (5) Add the modified magnesium oxide powder component B to component A while stirring, and stir and disperse for 5 minutes.

[0150] Analysis and testing:

[0151] 1. Prepare test samples

[0152] (1) Take a 20G metal substrate and use quartz sand with a particle size of 20 mesh to sandblast the substrate at a pressure of 0.6 MPa at a 45° angle. The construction environment is controlled at a temperature of 25°C and a relative humidity of 65%. The sandblasting requirement is that the substrate reaches Sa3.0 cleanliness and the surface roughness Rz>40μm.

[0153] (2) Before spraying, the surface of the substrate after sandblasting was subjected to soot blowing treatment. The prepared coating was stirred evenly and adjusted to a suitable viscosity with water. The viscosity was 30s for Tu Si Cup. An air spray gun with a diameter of 1.8 mm was used, and the air inlet pressure was controlled at 0.5 MPa. The distance between the spray gun and the coated surface was 40 cm, and the spray width was 40 cm. The spray gun was at a 90° angle to the coated surface.

[0154] (3) Spraying is completed in multiple times, with a total film thickness of 300±20μm. The surface must be fully dried between each spraying before the next spraying can be carried out. The wet film thickness of a single spraying is controlled within 150μm. After spraying is completed, it is left to dry for 6 hours. After the coating is completely dry, it is heated from room temperature to 180℃ and kept warm for 2 hours. The heating rate is controlled at 3℃ / min. After curing, the protective coating is prepared.

[0155] 2 Experimental results

[0156] The experimental samples prepared in Examples 1-4 and Comparative Examples 1-4 were tested:

[0157] Testing the activation period of the mixed coating: Observe the viscosity of the mixed coating and evaluate its performance by spraying at different time intervals and comparing it with the initial sample. Surface dry heat and humidity resistance: Tested according to the national standard GB / T1740-2007 for 48 hours at a temperature and humidity of 120°C and 90%. Pull-off adhesion is tested according to the national standard GB / T5210-2006. Surface tension and hydrophobicity are tested using a dyne pen and a water drop method. Acid corrosion resistance is tested according to GB / T 9274-1988, using 5% wt sulfuric acid and hydrochloric acid as the corrosive media. Non-scratch neutral salt spray resistance is tested according to the national standard GB / T1771-2007. Surface anti-fouling performance is tested by dripping high-temperature molten ammonium bisulfate onto the sample surface, cooling it, and then blowing it through with air at a rate of 20 m / s for comparison.

[0158] The specific results are shown in Table 1.

[0159] Table 1:

[0160]

[0161] In Comparative Example 1, the unmodified magnesium oxide coating gelled and solidified during stirring, making it unsuitable for coating. A comparison with Example 1 reveals that the modification of the magnesium oxide inhibits its activity, extending the two-component coating's application period and enabling on-site application. Comparative Example 2, compared with Example 1, reveals that the addition of modified magnesium oxide allows the coating to fully cure at 180°C, ensuring its effectiveness in low- to medium-temperature environments. The coating without modified magnesium oxide suffers from insufficient sintering temperature, leading to resin dissolution and pulverization after prolonged water contact, resulting in coating failure. Comparative Example 3, compared with Example 1, reveals that the addition of polysiloxane imparts a hydrophobic effect to the coating, improving its resistance to liquid-phase corrosion and surface-dry heat and humidity, while also protecting the coating from damage by flue gas vapor during drying. When polysiloxane is omitted from the formulation to modify the flaky metal, the coating's hydrophobic effect disappears, its heat and humidity resistance, corrosion resistance, and anti-fouling properties significantly decline, and the flaky metal powder cannot be oriented. Comparing Comparative Example 4 with Example 1, it can be found that the addition of flaky metal powder improves the corrosion resistance of the coating to a certain extent, mainly due to its directional arrangement on the surface of the paint film to form a dense protective layer, which improves the anti-penetration ability of the coating. In Comparative Example 5, since no polysiloxane-modified flaky metal powder was added, the anti-corrosion and anti-fouling properties of the coating decreased significantly, and the initial moisture and heat resistance was lost, affecting the coating performance. The anti-corrosion coating for the high-temperature heating surface of the waste power generation prepared by the present invention has surface-dry hydrophobicity and excellent surface-dry moisture and heat resistance. The coating can be cross-linked and cured in a medium-low temperature environment of 180°C, and the directionally migrated polysiloxane and flaky metal powder form an oily dense shielding layer on the surface of the coating. The coating has excellent film-forming anti-corrosion performance and excellent acid and salt spray corrosion resistance. It can be used for the surface corrosion protection of the water-cooled wall of the flue of waste power plants to replace traditional metal surfacing technology and reduce the frequency of pipe replacement in power plants.

[0162] It will be easily understood by those skilled in the art that the above 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 in the scope of protection of the present invention.

Claims

1. An anti-corrosion coating for high-temperature heating surfaces in waste-to-energy plants, characterized by: The coating material is composed of the following raw materials in parts by weight: 20-50 parts of high temperature resistant inorganic resin, 0.5-1.5 parts of modified magnesium oxide, 5-15 parts of rare earth oxide, 20-40 parts of ceramic powder, 3-5 parts of flaky metal powder, 1-5 parts of polysiloxane, 0.5-3 parts of leveling agent, 3-10 parts of passivating agent, 3-5 parts of butyl ether, and 0-20 parts of deionized water.

2. The anti-corrosion coating for high-temperature heating surfaces of waste-to-energy according to claim 1, characterized in that: The high-temperature resistant inorganic resin is liquid aluminum dihydrogen phosphate with a mass solid content of 45-52% and a resin Al / P molar ratio of 0.25-0.

28.

3. The anti-corrosion coating for high-temperature heating surfaces of waste-to-energy according to claim 1, characterized in that: The rare earth oxide is one of cerium oxide and yttrium oxide or a mixture of the two, and the powder particle size D50 is less than 20 μm.

4. The anti-corrosion coating for high-temperature heating surfaces of waste-to-energy according to claim 1, characterized in that: The ceramic powder is at least one of boron nitride, silicon nitride, and chromium oxide green, and the powder particle size D50 is less than 40 μm.

5. The anti-corrosion coating for high-temperature heating surfaces of waste-to-energy according to claim 1, characterized in that: The flaky metal powder is stearic acid-coated titanium powder, the powder particle size D50 is less than 25 μm, and the mass content of stearic acid is less than 5%.

6. The anti-corrosion coating for high-temperature heating surfaces of waste-to-energy according to claim 1, characterized in that: The polysiloxane is Wacker 5350 modified polysiloxane.

7. The anti-corrosion coating for high-temperature heating surfaces of waste-to-energy according to claim 1, characterized in that: The modified magnesium oxide preparation method comprises the following steps: (1) Calcined magnesium oxide was added to deionized water under high-speed stirring, and dispersed at high speed for 30-40 minutes under circulating water cooling to prepare a 50% wt dispersion slurry; (2) Take 100-150 ml of nano-silica sol, dilute it with an equal volume of deionized water, the colloid solid content is 20-30 wt%, the average particle size is 10-40 nm, and stir and disperse it under ultrasonic conditions for 5-10 minutes; (3) slowly adding the slurry of step (1) into the dispersion of step (2) under stirring, and stirring in an ice-water bath for 1-2 hours; (4) The slurry in step (3) is filtered through a 200-mesh filter, and the filtrate is rinsed with deionized water 1-2 times. After washing, the solid material is freeze-dried in a vacuum to remove moisture, and the powder after drying is modified magnesium oxide.

8. The method for preparing an anti-corrosion coating for a high-temperature heating surface of waste-to-energy according to any one of claims 1 to 7, characterized in that: The raw material preparation includes the following steps: (1) Preparing an anti-corrosion coating for a high-temperature heating surface of waste-to-energy power generation according to any one of claims 1 to 7; (2) Mix the high-temperature resistant inorganic resin with 1 / 2 deionized water, disperse it into a clear liquid phase, then slowly add the passivating agent, and then stir and disperse it for 10-20 minutes to form a uniform dispersion; (3) Diluting polysiloxane with butyl ether, adding flake metal powder, stirring evenly with a glass rod, and then placing it in ultrasonic dispersion for 15-20 minutes to obtain a mixed solution; (4) adding the mixed solution of step (3), rare earth oxide and ceramic powder to the dispersion of step (2) in sequence at a speed of 400-600 rad, and after the powder is fully wetted, dispersing at a high speed of 1000-1500 rad for 30 minutes under a circulating water cooling state to obtain a slurry; (5) adding a leveling agent to the slurry prepared in step (4), dispersing the mixture at 500-600 rad for 10 min, testing the slurry fineness to ensure that it is qualified, adjusting the viscosity with the remaining deionized water, and filtering the mixture to obtain the coating component A; (6) The modified magnesium oxide powder is the coating B component and can be dispersed by machine on site when used.

9. A method for constructing an anti-corrosion coating for a high-temperature heating surface of a waste-to-energy power plant, using the raw materials obtained by the method for preparing an anti-corrosion coating for a high-temperature heating surface of a waste-to-energy power plant according to claim 8, characterized in that: The following steps are involved: (1) Take a 20G metal substrate and use quartz sand with a particle size of 10-30 mesh to sandblast the substrate at a pressure of 0.6-0.8 MPa and an angle of 30-60°; the construction environment is controlled at a temperature of 5-35°C and a relative humidity of 0-85%. The sandblasting requires the substrate to reach Sa3.0 cleanliness and a surface roughness Rz>40μm; (2) Add component B to component A while stirring, and bend the mixture at 500 rad for 5-10 minutes. The coating is sprayed. Before spraying, the surface of the sandblasted substrate is soot-blown. The prepared coating is stirred evenly and adjusted to a suitable viscosity with water. Air spraying is used, and the air inlet pressure is controlled at 0.3-0.5 MPa. The distance between the spray gun and the coated surface is 20-40 cm, and the spray width is 20-40 cm. The spray gun is at an angle of 45-90° to the coated surface. (3) Spraying needs to be completed in multiple times, and the total film thickness is controlled at 300±20μm. The surface must be fully dried between each spraying before the next spraying can be carried out. The wet film thickness of a single spraying is controlled within 150μm; after spraying is completed, let it stand for 4-6 hours to dry. After the coating is completely dry, heat it from room temperature to 180℃ and keep it warm for 1-2 hours. The heating rate is controlled at 2-3℃ / min. After curing, the anti-corrosion coating is prepared.

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