KR101708795B1 - Coating composition with excellent high temperature acid-resistance and manufacturing method therewith - Google Patents

Abstract

The present invention relates to a high-temperature and acid-resistant coating composition for a gas heat exchange device of a thermoelectric power plant, which comprises 75 wt% of a sol-gel resin, 10 wt% of super-hydrophobic organic-inorganic composite powder, 5 wt% of aluminum oxide (Al_2O_3) powder and 10 wt% of titanium dioxide (TiO_2) powder, and a method for preparing the same. According to the present invention, it is possible to form a highly acid-resistant ceramic coating film having a surface hardness of 9H, high-temperature acid resistance (70% sulfuric acid, 80C) of 10 hours, 60C surface gloss of 43% and a water contact angle of 84 or more on a heat exchange device of a thermoelectric power plant. Thus, it is possible to prevent corrosion at high temperature, to inhibit scale formation, and to form a passivation film on a material made of a metal, such as magnesium, having low acid resistance, thereby providing increased durability thereto.

Description

TECHNICAL FIELD [0001] The present invention relates to a high-temperature acid-resistant coating agent for a thermal power plant gas heat exchanger,

TECHNICAL FIELD The present invention relates to a high-temperature acid-resistant coating agent for a thermal power plant gas heat exchanger, and more particularly to a high-temperature acid-resistant coating agent for inhibiting high temperature corrosion and scale formation of a thermal power plant heat exchanger made of carbon steel And a process for producing the same.

Generally, in the case of thermal power generation, the gas that burns coal contains corrosive gas at a high temperature of 150 to 180 ° C even after passing through the electrostatic precipitator.

The high temperature corrosive gas is composed of SO _x (SO ₂ , SO ₃ ) and reacts with CaO and fly ash when passing through a heat exchanger (hereinafter referred to as GGH (Gas Gas Heater)) to produce a hard scale This scale adheres well to the hydrophilic surface and interferes with the flow of gas. In severe cases, it increases the differential pressure of the flue gas of the GGH (gas gas heater) And the operation is also stopped.

At this time, GGH sends the high temperature gas from the boiler to the absorption tower at a low temperature, and warms the low temperature gas to the middle temperature (90 ° C) and sends it to the stack.

[Prior Art Literature]

1. Domestic Patent Disclosure: 1020120111050 (Publication date Oct. 10, 2012)

In order to solve the above problems, an object of the present invention is to provide a sol-gel resin composed of an organic-inorganic composite for inhibiting high-temperature corrosion and scale formation of GGH in a thermal power plant composed of a carbon steel element The present invention provides a coating agent prepared by dispersing and mixing a superfine hydrophobic powder and a ceramic filler synthesized therein, and a manufacturing method thereof.

In order to achieve the above-mentioned object, the high-temperature acid-resistant coating material of the thermal power plant gas-heat exchanging element of the present invention comprises 68 to 89 wt% of sol-gel resin, 5 to 20 wt% of super- hydrophobic organic- (Al ₂ O ₃ ) powder of 3 to 12 wt%, and titanium dioxide (TiO ₂ ) powder of 3 to 15 wt%.

Also, 14 ~ 16 mol% of Methyltrimethoxysilane (CH ₃ Si (OCH ₃ ), MTMS) and 15 ~ 25 mol% of Ethanol were mixed for 5 ~ 10 minutes and DI water And the mixture was stirred at room temperature for 2 hours. After stirring, the mixture was mixed with 0.01-0.2 mol% of 2-amino-2-methyl-1-propanol and stirred at room temperature for 12 hours to precipitate And the remaining wet gel is dried at 150 DEG C for 6 hours to obtain a solidified mass, and then the mass is pulverized to obtain an organic-inorganic composite (1 to 10 mu m in size) having a size of 1 to 10 mu m A first step of obtaining a powder of

MTMS, TEOS (Tetraethylorthosilicate) and PhTMS (Phenyltrimethoxysilane) were added, and the mixture was stirred for 5 to 10 minutes to prepare a silane mixed solution. Methoxy functional PDMS (polydimethylsiloxane), ethanol and acetic acid were added to the mixed solution and stirred at room temperature for 5 to 30 minutes A second step of adding an acidic silica colloid using water as a solvent and stirring at room temperature for 6 hours to obtain a transparent sol-gel resin,

And a third step of adding the organic-inorganic composite powder, aluminum oxide powder, and titanium dioxide powder obtained in the first step to the sol-gel resin prepared in the second step and dispersing the powders to obtain a ceramic coating agent do.

The effect of the present invention as described above is that by forming a high-acid-resistant ceramic coating film having a surface hardness of 9H, a high temperature acid resistance (70% sulfuric acid, 80 DEG C) for 10 hours, a 60 DEG surface gloss of 43% It is an extremely useful invention that can prevent high temperature corrosion and scale formation and enhance durability.

Fig. 1 is a photographic view of a pencil hardness and gloss measurement result of a high-acid-resistant ceramic coating agent for preventing scale of a GGH heat exchanging element.
Fig. 2 is a photograph of a contact angle measurement result of a ceramic coating substrate. Fig.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Also, the singular forms used herein include plural forms as long as the phrases do not expressly mean the opposite. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like. Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further construed to have meanings consistent with the relevant technical literature and the present disclosure and are not to be construed as ideal or official unless defined otherwise.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of a high-temperature acid-resistant coating agent and a method for producing the same of the thermal power plant gas heat exchanger according to the present invention will be described in detail with reference to the accompanying drawings.

High temperature acid resistant coating agent in the thermal power plant gas heat exchange device according to an embodiment of the present invention is sol-gel resin 68 ~ 89wt% , superhydrophobic (Super-hydrophobic) organic - 5 ~ 20wt% inorganic composite powder, aluminum oxide (Al ₂ O ₃ ) Powder of 3 to 12 wt%, and titanium dioxide (TiO ₂ ) powder of 3 to 15 wt%.

The sol-gel resin is a resin prepared through a sol-gel reaction, and functions as an oxygen covalent bond to the surrounding filler and substrate (carbon steel). In this case, since the amount of filler is relatively large, the surface of the coating film after coating is rough, and the adhesive strength and heat resistance are lowered. More than 90wt% of the coating film has a relatively small amount of filler, which degrades the acid resistance of the coating film. Therefore, the preferred addition amount is 68 to 89 wt%. The most preferable amount added is 75 wt%.

The super-hydrophobic organic-inorganic composite powder is a super-hydrophobic powder for inhibiting scale formation and exhibits heat resistance at 400 to 500 ° C. At this time, less than 5wt% of the coatings have poor surface hydrophobic properties after forming the coating film, and more than 20wt% of the coatings are layer disassociated in the coating agent (phenomenon that they are not mixed with the water contained in the coating agent to cause phase separation) . Therefore, the preferable amount is 5 to 20 wt%. The most preferable amount added is 10 wt%.

The aluminum oxide powder is used as an abrasion resistant material and a refractory material mainly because it is excellent in chemical resistance and abrasion resistance. In this case, the surface hardness is lowered to 3 wt% or less, and the titanium dioxide powder and the organic- The addition amount is 3 to 12 wt% because it decreases hydrophobicity and heat resistance. The most preferable amount added is 5 wt%.

The titanium dioxide powder is a ceramic excellent in chemical resistance, abrasion resistance and harmlessness of human body, and has a very small particle size, which is effective for microfilling and increases the concealment rate of the coating. Less than 3wt% And more than 15wt%, the addition amount of the aluminum oxide powder and the organic-inorganic composite powder is decreased, which hinders the hydrophobicity and the chemical resistance. Therefore, the most preferable range is 3 to 15 wt%. The most preferable amount added is 10 wt%.

The method for producing a high-temperature acid-resistant coating agent for a thermal power plant gas heat exchanger according to the present invention comprises mixing 14 to 16 mol% of Methyltrimethoxysilane (CH ₃ Si (OCH ₃ ), MTMS) and 15 to 25 mol% of ethanol and stirring for 5 to 10 minutes, The mixture was stirred at room temperature for 2 hours with 45 ~ 65mol% of DI water and 0.01 ~ 0.1mol% of acetic acid. After stirring, 0.01-0.2mol of 2-amino-2-methyl-1-propanol was added and stirred at room temperature for 12 hours To obtain a precipitated wet gel. The supernatant of the wet gel is removed and the remaining wet gel is dried at 150 DEG C for 6 hours to obtain a solidified mass. The mass is pulverized to obtain an organic- Inorganic composite powder;

MTMS, TEOS (Tetraethylorthosilicate) and PhTMS (Phenyltrimethoxysilane) were added, and the mixture was stirred for 5 to 10 minutes to prepare a silane mixed solution. Methoxy functional PDMS (polydimethylsiloxane), ethanol and acetic acid were added to the mixed solution and stirred at room temperature for 5 to 30 minutes A second step of adding an acidic silica colloid (SiO ₂ concentration: 30%) using water as a solvent and stirring at room temperature for 6 hours to obtain a transparent sol-gel resin,

A third step of adding the organic-inorganic composite powder, the aluminum oxide powder, and the titanium dioxide powder obtained in the first step to the sol-gel resin prepared in the second step and dispersing the powders to obtain a ceramic coating agent.

Ethanol content is in the range of 15 ~ 25 mol% when 14 ~ 16 mol% of Methyltrimethoxysilane (CH ₃ Si (OCH ₃ ), MTMS) is allowed. It is hard to expect MTMS homogeneous dispersion reaction below 14 mol% MTMS and 15 mol% Ethanol , 16mol% of MTMS and more than 25mol% of ethanol delays gelling reaction and delay time to obtain xerogel.

The DI water (deionized water) is suitably 45 to 65 mol%, the MTMS hydrolysis rate is slow or the partial hydrolysis is completed and the chemical uniformity is lowered. When the molar ratio is more than 65 mol%, the hydrolysis rate Because it slows down the time to obtain the xerogel because the polymerization rate is slow.

The acetic acid is suitably 0.01 to 0.1 mol%, and when it is 0.01 mol% or less, the hydrolysis rate becomes too slow, and when the molar ratio exceeds 0.1 mol%, the hydrolysis rate becomes too fast and the homogeneous sol-gel reaction can not proceed .

0.01 to 0.2 mol% of the 2-amino-2-methyl-1-propanol is suitable. When the amount is less than 0.01 mol%, the gelation rate is too slow and more than 0.2 mol% .

The MTMS is a material which is hydrolyzed and then bonded to the surface of silica colloid and crosslinked with other silane to form a three-dimensional organic-inorganic composite resin having Si (silicon) as a central metal to form a resin. The adhesive strength is lowered, and when it is 25 wt% or more, the solvent becomes relatively insufficient. Therefore, the added amount is preferably 20 to 25 wt%.

The TEOS is hydrolyzed to connect the MTMS oligomers to each other or to form nano-sized SiO ₂ particles. When the addition amount is less than 0.5 wt%, the coupling effect of coupling the hydrolyzed MTMS to each other is insignificant Cracks are frequently generated after the formation of the coating film, and when it is 5.0 wt% or more, the adhesion of the coating film is deteriorated. Therefore, the added amount is preferably 0.5 to 5 wt%.

The PhTMS is a silane having a phenyl group and is hydrolyzed to bind to MTMS, TEOS and the like and increase the resistance to sulfuric acid. When the content is less than 2.0 wt%, the resistivity to concentrated sulfuric acid becomes low, It is difficult to obtain a homogeneous sol-gel resin due to the partial phase separation in the solution, and the cracking phenomenon of the coating film is also severe. Therefore, the preferable amount is 2.0 ~ 8.0 wt%.

The methoxy functional PDMS has a chemical structure in which -OCH ₃ (methoxy) groups are bonded to one terminal or both terminals or side chains of PDMS (polydimethylsiloxane), and functions to impart dysplasia and water repellency during film formation. The water repellency of the coating film is weak, and when 1.5 wt% or more, many pinholes and craters are generated in the coating film to deteriorate the surface roughness, so that the preferable amount is 0.05 to 1.5 wt%.

Ethanol is a silane dilution solvent such as MTMS, TEOS and PhTMS, and it determines the rate of hydrolysis, the shape of nanoparticles, and the volatilization rate during the formation of the coating film. In the case of 30 wt% or less, , And when it is 50 wt% or more, the silane concentration is lowered to decrease the density of the coating film, so that the added amount is preferably 30 to 50 wt%.

Acetic Acid increases the hydrolysis rate as a weak acid and affects the viscosity stability of the solution during the sol-gel reaction. When the concentration is less than 0.1 wt%, the hydrolysis rate is too slow, %, The hydrolysis rate is too fast to form a non-homogeneous sol solution, so that the preferable addition amount is 0.1 to 1.0 wt%.

The acidic colloidal silica is an acidic colloidal silica containing water (H ₂ O) as a solvent. There are colloidal solutions of various sizes ranging from several nanometers to several hundreds of nanometers. In the present invention, nanoparticles having a size of 10 to 20 nm Was dispersed in water. Since the acidic silica colloid is composed of silica nanoparticles, water and a small amount of a stabilizer, the acidic silica colloid itself becomes a source of water necessary for hydrolysis.

Therefore, hydrolysis of silane is insufficient because the amount of water is less than 20 wt%, the strength of the coating film is increased by 45 wt% or more, but the opacity is increased and the storage stability of the sol-gel resin is lowered. %to be.

A preferred embodiment of the method for manufacturing a high-temperature acid-resistant coating agent of the present invention of the present invention is as follows.

Example

15.37 mol% of Methyltrimethoxysilane (CH ₃ Si (OCH ₃ ), MTMS) and 23.05 mol% of Ethanol are mixed and stirred for several minutes. To this solution, 61.46 mol% of DI water (deionized water) and 0.03 mol% of acetic acid are added and stirred at room temperature for 2 hours. After the stirring, 0.09 mol% of 2-amino-2-methyl-1-propanol was added and stirred at room temperature for 12 hours to obtain a precipitated wet gel (xerogel). The supernatant of this wetting gel (layer separated and separated solution at the top) is removed and the remaining wet gel is dried at 150 ° C for 6 hours to obtain a solidified mass. The mass is pulverized to obtain an organic-inorganic composite powder having a size of about 1 to 10 mu m. The chemical formula of this powder can be expressed as CH ₃ SiO _2-x (x <2). Instead of MTMS, C _n H _{2n + 1} Si (OR) can be used instead of MTMS. (n is a natural number from 1 to 16 and OR is methoxy or ethoxy or propoxy or acetoxy).

Next, 25.245 wt% of MTMS (Methyltrimethoxysilane), 1.158 wt% of TEOS (tetraethylorthosilicate) and 4.692 wt% of PhTMS (Phenyltrimethoxysilane) were added and stirred for several minutes to prepare a silane mixed solution. Methoxy functional PDMS (Methoxy terminated polydimethylsiloxane) (0.2 wt%), ethanol (39.9 wt%) and acetic acid (0.6 wt%) were added to the mixed solution and stirred at room temperature for several to several tens of minutes. A transparent sol-gel resin was prepared by adding 28.205 wt% of an acidic silica colloid (SiO ₂ concentration 30%) using water as a solvent and stirring at room temperature for 6 hours.

10wt% of super-hydrophobic organic-inorganic composite powder prepared in <1 step> and 10wt% of aluminum oxide (Al ₂ O ₃ , average particle size of 1 μm) were added to 75wt% of the sol- ) 10 wt% of powder of titanium oxide (TiO _2, average particle size of 0.4 탆) was added and the powder was dispersed by using a ball mill or a basket mill to prepare a ceramic coating agent do.

The highly acid resistant ceramic coating thus prepared was measured to have excellent pencil hardness, gloss and contact angle as shown in Figs. 1 and 2.

Although the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the present invention is not limited thereto and that various changes and modifications will be apparent to those skilled in the art. Various modifications and variations are possible within the scope of the appended claims.

Claims (2)

68 to 89 wt% of a sol-gel resin containing MTMS, TEOS, PhTMS, polydimethylsiloxane, ethanol, water, acetic acid and silica colloid, 5 to 20 wt% of a superhydrophobic organic- Al ₂ O ₃ powder, 3 to 12 wt%, and titanium dioxide (TiO ₂ ) powder, 3 to 15 wt%.


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