JPS636317A - Method of preventing corrosion of inner surface of smoke passage - Google Patents

Abstract

PURPOSE:To prevent gas and liquid from permeating the inner surface and improve an effect of corrosion-proof characteristic by a method wherein a ground processing is applied to the inner surface with a sand blasting process and then silicon coating agent is applied by two times, and a fluorine coating agent is applied on an upper surface to perform a finishing work. CONSTITUTION:The inner surface of a smoke passage is well ground or polished with sand blasting to make a ground processing. Then, silicone coating agent is separately applied by two times and two layers of coat film are formed. A fluorine coating agent is applied to the upper surface of the silicon coat film to form a fluorine coat film. With this arrangement, the smoke passage may show a quite high corrosion-proof effect under a cooperative action of heat-resistance of fluorine coating agent and anti-acid characteristic of silicon coating agent and at the same time a disadvantage of making pin holes can be eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flue made of steel or the like,
It is a 1 liter unit installed vertically for exhaust heat and exhaust gas.

In particular, the present invention relates to a method for preventing corrosion of the inner surface of a flue in order to improve heat resistance and corrosion resistance.

[Conventional technology]

We will explain a typical example of the conventional 2-type steel construction method (1" Lfc construction method adopted to impart corrosion resistance to the inner surface of the flue. First, we will explain its configuration. It is formed into a planar shape and is designed to exhaust combustion exhaust gas and the like.

The VC in front of this flue is equipped with an air dust collector and flue gas desulfurization equipment to remove dust from the flue gas, clean it, and discharge it to the atmosphere. However, the actual situation is that the inside surface of the flue is severely corroded due to trace amounts of corrosive components, moisture, and dust in the exhaust gas, which are not removed by such removal systems.

Therefore, conventionally, graphite has been used as a corrosion prevention method. The next step is to use only silicone-based paint and apply it to the inside of the flue. However, due to the amount and shape of the blended a7'5 graphite particles, the coating film properties are porous and
On the surface of the coating, unevenness is naturally formed. Due to the penetration of the sulfuric acid mist, etc., the vC-silicon paint and coating film often peeled off within a short period of time, causing corrosion on the inner surface of the flue. Historically, because the coating film contained graphite particles, it was not possible to conduct an electrical pinhole test, and even a quality check was not sufficient.

[Problem that the invention seeks to solve]

Since the conventional construction method has the defects mentioned above, this method overcomes these defects, protects the inner surface of the flue from corrosion, eliminates the conventional defects such as pinholes, and prevents gas and liquid penetration.

This raises a problem that needs to be solved regarding a corrosion-proofing method for the inner surface of the flue that has a higher corrosion-proofing effect.

[Means for solving problems]

This invention was proposed in view of the above-mentioned problems of the conventional VC, and was proposed as a two-way solution.
The inner surface of the flue for waste heat and exhaust gas was prepared by sandblasting, and silicone paint was applied in two parts.1! Another object of the present invention is to provide a method for preventing corrosion of the inner surface of a flue, which is characterized in that the upper surface is completely coated with a fluorine-based paint.

[Function] In this invention, the silicone-based paint applied to the inner surface of the flue is coated in two separate coats.

In addition, the coating film is formed in a double layer, so that the I/C is formed, and further,
Completely coat the top surface with fluorine paint and use fc pins.

This fluorine-based paint is heat resistant to the heat rc passing through the flue, does not peel off easily, and completely protects the silicone-based paint coated on the back surface. Historically, since the silicone-based coating film is also formed in two layers, the inner surface of the flue is extremely strongly protected, and the heat resistance and corrosion resistance of the IC are extremely high.

[Examples and experimental examples]

The present invention will be explained in detail below. The flue is made of steel as before. First, the inside surface of this flue was well polished by sandblasting.

Perform surface treatment. The silicone-based paint is then applied in two separate coats, and the thickness of the coat is generally determined accordingly. 4 items follow.

Strictly speaking, this coating film made of silicone paint is formed in two layers and is called NFT-RC. Next, a fluorine-based paint is applied to the upper surface of the fL layer formed by this silicone-based paint, and then applied to the upper surface of the m-layer of the silicone-based paint.

Shape the fluorine-based paint film. The thickness of this coating film shall be reduced as appropriate.In this way, the ft flue processed by the single-layer anti-corrosion method will have the heat resistance of the fluorine-based paint and the acid resistance of the silicone-based paint. As a result, the flue exhibited an extremely high corrosion-proofing effect, and all defects such as pinholes that were present in the conventional method were completely eliminated. □Also, we experimented with a test piece processed using the method of the present invention, and compared it to the conventional product. In comparison, the following data was obtained.

In addition, in the hot sulfuric acid corrosion test, 5% sulfuric acid 1
Out? Various test pieces were infiltrated for 6 hours.

Also, peeling and swelling of the paint film on the appearance.

A test was carried out by cutting a 2 mrn square with a 25 frame knife and peeling off all 9 parts with adhesive tape. Appearance is acceptable if there is no peeling or swelling, and if the adhesive tape does not peel off easily.

That is, as shown in the table below, according to this construction method.

It turns out that the heat resistance and corrosion resistance are the same as above.

[Purpose of test]

First, the initial test was conducted to select a corrosion-resistant material for the inner wall protection 111, since the inner surface of the flue is subject to dew condensation and the shadow 41 of H2SO<, etc., depending on the operating conditions, and is susceptible to corrosion. An accelerated test was conducted.

[Test method]

5% H2SO4
The whole day's immersion test is done.

(B) Specimen specifications: All steel plates with severe corrosion were selected and sandblasted to prepare a specimen (shape: 60 x 80 x 3.2 tons). and microscope (8
0 times) fbl Weight change rate Icl on the 5th and 10th day of weight change Adhesion test Goban test on the 5th day and IQ day H corrosion resistance test ial Chemical solution: 5X HzSO4 1bl Temperature and cycle fat attached attached Figure 1 shows the test piece (1) placed in the test container (3) and heated with the heater (2).

It is completely immersed in high temperature for 8 hours.9.

9! ! In addition, FIG. 2 shows a test conducted for 16 hours at room temperature and in a gaseous state.

) Peel off with Sellotape using Goban-me Testro 2mm x 25 frames)
? After doing this, I made a table with the number f n/25.

〔test results〕

A1 Weight change Heat-resistant silver loses a lot of weight on the second day, compared to IX units, and chemical corrosion of the iron skin occurs.

The MS-NF type is a little less than -0.2%.

(Mouth 1 Bread test ACT also caused an interlayer hack IJ.

Some of the heat-resistant silver peeled off with cartilage ○ H3-NF series showed no abnormality c) Appearance test Heat-resistant silver showed t o mm ~ 15” mm on the second day.
A large bubble was generated, and bubbles were also generated, and the process was discontinued on the second day.

On the 3rd day of ACT, a rash appeared, and as time progressed, the entire area became more irritated.

There was no abnormality in the MS-NF system. 2) Microscopic ACT showed that 7 to 8 lower layers were formed in the mouth of the 2S of the order Gobanales.

There is no abnormality in the MS-NF system. [Test considerations] After considering the test, I found out the following.

The MS-NF system has outstanding corrosion resistance compared to others.

ACT is not suitable for high heat to sulfuric acid type 1c as it generates fu<'n'r.

(c) Heat-resistant silver has almost no corrosion resistance.

[BRIEF DESCRIPTION OF THE DRAWINGS] The figures are schematic diagrams of a corrosion resistance test. FIG. 1 is a schematic diagram of a test in a high temperature complete immersion state, and FIG. 2 is a schematic diagram of a test in a normal temperature vapor phase state. Code explanation (1)...Test piece (2)...
・Heater (3)...Patent attorney representing test container Takayoshi Hayashi Figure 1 Procedural amendment (spontaneous) 20 Title of invention Corrosion prevention method for inner surface of flue 3 Relationship with the case of the person making the amendment Patent Applicant Address D 8 Maruei Sangyo Co., Ltd. 4, Agent 5, Subject of Amendment 6, Contents of Amendment tl+ The table listed under line 9 on page 6 of the specification is amended as follows.

Claims (1)

[Claims] The inner surface of the flue for exhaust heat and exhaust gas, which is made of steel etc., is prepared by sandblasting, then silicone paint is applied in two parts, and then fluorine paint is applied to the top surface. A corrosion prevention method for the inner surface of the flue, which is characterized by coating and finishing.