JPH058325B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method of lining the inner surface with a flake lining compound made of unsaturated polyester resin or vinyl ester resin and glass flakes and/or mica flakes, and lining the inner surface with an inorganic material. This invention relates to a method for preventing corrosion of chimneys.

Conventional technology In the past, steel chimneys and reinforced concrete chimneys for smoke exhaust equipment such as boiler exhaust gas and incinerator exhaust gas were lined directly with inorganic materials such as castable or anti-flame stone on the inside of the chimney for the purpose of heat insulation and corrosion resistance. are doing.

Problems to be Solved by the Invention In general, exhaust gas from a boiler that burns heavy oil or coal is desulfurized by a flue gas desulfurization device, and then
It is discharged from the chimney. Furthermore, exhaust gas from an incinerator or the like is cleaned by a cleaning tower and then discharged from a chimney.

Almost all of these exhaust gas treatment methods use neutralizing/absorbing liquids such as sodium sulfite and caustic soda to neutralize and absorb harmful corrosive substances such as sulfur oxides (SOx) and hydrochloric acid gas (HCl). Since this is a so-called wet method, the exhaust gas is inevitably a low temperature (around 60℃) water-saturated gas, and corrosive substances such as SOx and HCl remaining in the exhaust gas condense on the inside of the chimney, causing If the exhaust gas is from a heavy oil-fired boiler after desulfurization, a strong acid such as sulfuric acid with a pH of 1 to 3 will adhere to it.

This acidic liquid penetrates through the inorganic lining materials on the inside of the chimney that were conventionally used, such as castable and firestone, and reaches the steel and concrete layers that make up the chimney structure, corroding them and causing holes. This may even cause the chimney itself to collapse.

In order to prevent the above-mentioned corrosion, a method has been implemented in which low-temperature exhaust gas treated by flue gas desulfurization or the like is reheated using an afterburner to maintain the temperature at or above the dew point of the exhaust gas.

Furthermore, depending on the equipment, exhaust gas may be discharged from the chimney at a high temperature without undergoing treatment such as flue gas desulfurization.

Therefore, even if the temperature of the exhaust gas is above the dew point,
Conventional linings made of inorganic materials such as castable and anti-firestone cannot block the penetration of acidic substances and moisture in exhaust gas, and acid and moisture penetrate the inorganic lining, causing damage to the lining layer itself or to the lining layer. Condensation occurs at the interface with chimney structural materials such as steel, and the condensed acid and moisture inevitably corrode the chimney structural materials themselves, such as steel and concrete. In addition, the reheating method using an afterburner uses a large amount of heating source, which is not only economically disadvantageous but also requires the installation of auxiliary equipment, which is not a satisfactory technology. When reheating, the combustion of fuel increases air pollutants such as NOx and COx in the exhaust gas.

As mentioned above, in order to prevent corrosion due to corrosive substances in exhaust gas, conventional chimneys require annual repairs and major renovation of the lining.

Means for Solving the Problems The present invention has been made in view of the above facts, and aims to provide a corrosion prevention method that provides chimneys with sufficient durability over a long period of time.

As a result of extensive research and experiments, the present inventors lined the inner surface with a flake lining compound consisting of unsaturated polyester resin or vinyl ester resin, glass flakes and/or mica flakes (hereinafter referred to as flake lining), and By lining the top with an inorganic material such as castable or anti-flame stone (hereinafter referred to as inorganic lining), it can be used against treated gases treated by flue gas desulfurization, etc., as well as treated gases heated with afterburners. Furthermore, they discovered that corrosion of steel and concrete can be prevented even by untreated high-temperature gases, leading to the completion of the present invention.

That is, the present invention provides a corrosion protection method for a chimney characterized by lining the inner surface with a flake lining compound made of unsaturated polyester resin or vinyl ester resin and glass flakes and/or mica flakes, and lining the inner surface with an inorganic material. It's a method.

The unsaturated polyester resin used in the present invention is prepared by dissolving an esterified polycondensate of a dibasic acid component and a glycol component in a polymerizable monomer. Examples of the dibasic acid component include α,β-unsaturated dibasic acids such as maleic acid, maleic anhydride, fumaric acid, and itaconic acid, and optionally, isophthalic acid, phthalic anhydride, and terephthalic acid. Acids, saturated dibasic acids such as Hett's acid, adipic acid, tetrachlorophthalic anhydride, etc. may be added. On the other hand, the glycol component includes, for example, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, bisphenol A dioxyethyl ether adduct,
It is selected from bisphenol A dioxypropyl ether adducts, hydrogenated bisphenol A, ethylene oxide, propylene oxide, etc., and if necessary, polyhydric alcohols such as trimethylolpropane and glycerin are used together. You can also do that. Further, as the polymerizable monomer, styrene, α-methylstyrene, vinyltoluene, etc. are used. The unsaturated polyester resin containing the polymerizable monomer may contain, for example, hydroquinone, benzoquinone, t
A polymerization inhibitor such as -butylcatechol, or a polymerization accelerator such as cobalt naphthenate, N,N'-dimethylaniline, or cobalt octenoate can be added.

The vinyl ester resin used in the present invention is produced by reacting a bisphenol type polyepoxide represented by the following general formula () or a novolak type polyepoxide represented by the following general formula () with an ethylenically unsaturated monocarboxylic acid. An ester compound dissolved in a polymerizable monomer is used.

(However, R: -H, -CH ₃ , X: -H or halogen, 0≦n≦20) (However, R': -H, _-CH3 , 0≦n'≦12).

Examples of the ethylenically unsaturated monocarboxylic acids include methacrylic acid, acrylic acid, and crotonic acid. Further, as the polymerizable monomer, styrene, α-methylstyrene, vinyltoluene, etc. are used. As the unsaturated polyester resin containing the polymerizable monomer, for example, hydroquinone, benzoquinone,
A polymerization inhibitor such as t-butylcatechol or a polymerization accelerator such as cobalt naphthenate, N,N'-dimethylaniline, or cobalt octenoate can be added.

The glass flakes and mica flakes used in the present invention usually have a particle size of 0.1 mm, preferably 0.01 mm to 1 mm.

A flake lining compound is usually made by adding 5 to 100 parts by weight of glass flakes, mica flakes, or a mixture thereof to 100 parts by weight of resin, uniformly dispersing the mixture by stirring and mixing, and adding silicone-based compound as necessary. Antifoaming agents such as antifoaming agents, thixotropic agents such as SiO ₂ fine powder, and additives such as pigments may be added.

A specific example of the method for preventing corrosion of a chimney according to the present invention will be described below with reference to the accompanying drawings. In FIG. 1, a flake lining 2 is constructed on the inner surface of a chimney body 1 made of steel or reinforced concrete. Flake lining 2
After completion of construction, inorganic lining 3 will be constructed.

The construction thickness of flake lining is 0.1
It is preferable to set the thickness to 3 mm from the viewpoint of corrosion prevention of the chimney body and economical efficiency, but there is no particular limitation.

The inorganic lining is designed to have a surface temperature of 10 to 10% from the viewpoint of heat insulation and economical efficiency, so that the surface temperature of the flake lining is below the heat-resistant temperature of the flake lining.
The thickness is 150mm, but there is no particular limitation.

As the material for the inorganic lining, water glass castable, cement castable, anti-flinder rock, ceramic foam, etc., which are conventionally used as chimney linings, can be used.

Function Flake lining using unsaturated polyester resin or vinyl ester resin has very good corrosion resistance against corrosion caused by corrosive substances such as SOx and HCl contained in flue gas emitted from chimneys. , makes an excellent lining. however,
The coefficient of thermal expansion of flake lining is larger than that of the steel or concrete that makes up the chimney body, and as the temperature rises, the strain difference increases, causing peeling and cracking, and the lining no longer functions as a lining.

In contrast, inorganic linings can be used at high temperatures, but cannot prevent the penetration of corrosive substances in the exhaust gas.

In the corrosion prevention method according to the present invention, high temperature gas in the chimney is insulated with an inorganic lining layer, the temperature at the flake lining surface is lowered to below the heat resistance limit of the flake lining, and corrosive substances that penetrate the inorganic lining layer are Corrosion protected with flake lining layer.

Example Examples and comparative examples of the present invention are shown below.

Example 1 Exhaust gas after flue gas desulfurization (temperature 56℃, SOx 120ppm
include. ) After sandblasting the inner surface of a steel chimney with a diameter of 1.5 m to discharge
Product name) and bisphenolic unsaturated polyester resin ester, which is an unsaturated polyester resin.
Glass flakes CCF150 (manufactured by Nippon Glass Fiber Co., Ltd.) with an average particle size of 0.1 mm are added to 100 parts by weight of R2110 (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name).
40 parts by weight of a flake lining compound with 0.7 parts of cobalt naphthenate as a hardening accelerator;
Methyl ethyl ketone peroxide as curing agent
Flake lining was applied to a thickness of 1.0 mm using 1.0 parts by weight. Furthermore, after the flake lining was completed, a 50mm thick water glass castable was applied as an inorganic lining over the flake lining. After using this chimney for one year, we checked for corrosion on the inner surface of the steel chimney body, and found that there was no red rust, and there was no corrosion of the base material.

Example 2 Recovery boiler exhaust gas (temperature 150℃, SOx 200ppm
include. ) Flake lining and inorganic lining were constructed by the same method as shown in Example 1 to a steel chimney with a diameter of 2.0 m for discharging. After using this chimney for one year, we checked for corrosion on the inner surface of the steel chimney body, and found that there was no red rust, and there was no corrosion of the base material.

Comparative Example 1 Only flake lining was applied to a part of the chimney in Example 1 by the method shown in Example 1. 2 Only inorganic lining was applied by the method shown in Example 1. After using this chimney for one year, we checked for corrosion on the inner surface of the steel chimney, and found that no corrosion was found in the base material of the part where only flake lining was applied, but in the part where only inorganic lining was applied. Red rust occurred and corrosion of the base material was observed.

Comparative Example 2 Only flake lining was applied to a part of the chimney in Example 2 by the method shown in Example 1. 2 Only inorganic lining was applied by the method shown in Example 1. After using this chimney for one year, we checked for corrosion on the inner surface of the steel chimney, and found that some cracks appeared in the flake lining layer in areas where only flake lining was applied, and the base material was damaged along these cracks. Red rust indicating corrosion of the base material was observed. For areas where only inorganic lining has been applied,
Red rust, which indicates corrosion of the base material, was observed.

Effects of the Invention As explained above, by the corrosion prevention method of the present invention,
Chimney corrosion due to exhaust gases such as low-temperature moisture-saturated exhaust gas that has been treated with flue gas desulfurization, treated gas heated with an afterburner, and untreated exhaust gas that contains large amounts of corrosive substances such as SOx and HCl. The chimney can be used safely, exhibiting sufficient durability for long-term use. Therefore, annual repairs and major renovations are not required, which is very advantageous in terms of maintenance. Furthermore, reheating by afterburner can be stopped, which is not only economically advantageous, but also reduces NOx and NOx in exhaust gas when reheating is performed using fuel.
It can reduce air pollutants such as COx.

[Brief explanation of the drawing]

FIG. 1 is an example of a sectional view of a chimney that has been lined by the method of the present invention, and FIG. 2 is a partially cutaway side view of a chimney that has been lined by the corrosion prevention method of the present invention. 1...Chimney body, 2...Flake lining,
3...Inorganic lining.

Claims (1)

[Claims] 1. A method for preventing corrosion of a chimney, which comprises lining the inner surface with a flake lining compound made of unsaturated polyester resin or vinyl ester resin, glass flakes and/or mica flakes, and lining the inner surface with an inorganic material.