JPH0829095A - Open rack type carburetor - Google Patents

Abstract

PURPOSE:To reduce the wear and tear of an aluminum alloy flame coating film by sequentially laminating and curing a sealing agent with permeability to the aluminum alloy flame coating film or the like and an epoxy resin or the like whose function as a sacrifice anode is not deteriorated on the surface of a heat exchanger panel made of an aluminum alloy material. CONSTITUTION:A protective film 5 on the surface of the heat exchanger panel of an open rack type carburetor includes a flame coating film 2 formed by flame coating aluminum alloy such as Al-Zn alloy on the surface 1 of a base metal made of an aluminum alloy material of the heat exchanger panel. Then, an achromatic and transparent or little pigment including a sealing agent 3 which has permeability to the flame coating alloy film 2 is applied to the film 2 and cured. Thus, pores in the flame coating film 2 are closed so that the film is integrated with the agent and strengthened. Further, a surface layer resin 4 of an epoxy resin or urethane resin is applied to the sealing agent 3 and cured so that the function of the flame coating film 2 as a sacrifice anode is not deteriorated. Thus, excellent sea-water resistance, cold resistance and abrasion resistance are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an open rack type vaporizer for vaporizing liquefied natural gas, which has an aluminum alloy sprayed film and a permeable colorless and transparent film on the surface of a heat exchange panel made of an aluminum alloy material. Sealing agent and coating resin are laminated in order to seal and strengthen the alloy sprayed film, and protect the alloy sprayed film from repeated freezing and abrasion caused by sand and solid matter in seawater. The present invention relates to an open rack type vaporizer having corrosion resistance.

[0002]

2. Description of the Related Art An open rack type vaporizer for vaporizing liquefied natural gas (hereinafter referred to as LNG) is constructed by, for example, arranging fin tubes having fins protruding in a diametrical direction in parallel to form a panel-like heat. An exchange panel is constructed. The fin tube and the header tank are made of Al-Mn system,
Aluminum alloy materials such as Al-Mg type and Al-Mg-Si type are used.

In such an open rack type vaporizer, for example, LNG is flowed upward from below the internal passage, and seawater as a heat source is flowed down to the outer surface of the heat exchange panel for heat exchange, so that the aluminum alloy material is protected. In order to protect the surface of the alloy base material,
That is, for the purpose of cathodic protection, an aluminum alloy sprayed coating such as an Al-Zn-based sacrificial anode,
It is deposited by means such as thermal spraying to a thickness of about several 100 μm.

The aluminum alloy sprayed coating deposited on the surface of the heat exchange panel of the open rack type vaporizer plays a role as a sacrificial anode for cathodically protecting the base material of the heat exchange panel from the corrosive action of the heating medium. As a result, the wear rate inevitably gradually decreases with the passage of time, but the wear rate is extremely slow when there are no other significant wear promoting factors, and the normal wear life is around 10 years or more. .

[0005]

However, there are cases in which the wear life of the aluminum alloy sprayed coating is remarkably shortened depending on the operating conditions and environmental conditions of the open rack type vaporizer. Therefore, as a result of detailed investigation of the mechanism of wear, which is the cause of it, the promotion of wear was found to be due to the corrosion reaction by the usual electrochemical process,
p-160 ° C.), mainly on the surface of the vaporizer heat exchange panel, physically and mechanically abraded by the repeated freezing occurring below the heat exchange panel near the LNG inlet, and when the heating medium is seawater, it is included therein. Due to the superposition of the mechanical wear effect due to marine organisms such as shellfish and solid matter such as mud sand scratching and impacting the surface of the heat exchange panel,
It was proved to be due to the action of erosion and corrosion.

That is, the physical action of volume expansion due to freezing and the mechanical abrasion action of being rubbed with hard ice,
The thermal spray coating is gradually worn away by repeating these actions, and when seawater flowing down in a liquid film on the vaporizer heat exchange panel surface contains a large amount of marine organisms such as shellfish and solid matter such as mud and sand, they are The aluminum alloy sprayed coating on the surface of the heat exchange panel is gradually mechanically abraded by the so-called sand erosion effect. These physical
The combination of mechanical wear and electrochemical corrosion as a sacrificial anode is the erosion-corrosion effect, which is the most severe of the LNG open rack vaporizer heat exchange panels, where repeated freezing and seawater drop impacts occur. In general, the wear of the aluminum alloy sprayed coating below the heat exchange panel is generally fast, centering on the upper surface of the lower header tank that receives the heat.

The present invention is based on the findings obtained by the above-mentioned investigation, and is an open rack type vaporizer having a structure excellent in erosion resistance and corrosion resistance and capable of reducing wear of an aluminum alloy sprayed coating of a heat exchange panel. For the purpose of providing.

[0008]

According to the present invention, an aluminum alloy sprayed film is formed on the surface of a heat exchange panel made of an aluminum alloy material of an open rack type vaporizer, and a small amount of pigment having permeability to the alloy sprayed film. Alternatively, the open rack type vaporizer is characterized in that a colorless and transparent sealing agent and an epoxy resin or urethane resin that does not impair the function of the alloy sprayed film as a sacrificial anode are sequentially laminated and cured. Further, in the present invention, in the above-mentioned constitution, the film thickness of the alloy sprayed film, the penetrating sealing agent, and the surface layer epoxy resin or urethane resin is 70 to 40, respectively.
We also propose an open rack type vaporizer that is sequentially laminated at 0 μm, 15 to 30 μm, and 45 to 60 μm.

In the present invention, the aluminum alloy sprayed coating formed by thermal spraying on the base material is an Al--Zn alloy (A7) which acts as a sacrificial anode for the aluminum alloy base material.
072), Al-In, Al-Sn, Al-In-
Zn, Al-Sn-Zn, etc. are suitable.

The aluminum alloy sprayed coating on the surface of the heat exchange panel is exposed to seawater containing marine organisms such as shellfish and solid matter such as mud and sand flowing down in a liquid film on the outer surface,
Especially below the heat exchange panel, the surface is frozen due to the cold heat (Bp-160 ° C) of LNG flowing through the internal passage,
The protective coating must be seawater-resistant, cold-resistant, and abrasion-resistant, and furthermore, it sufficiently closes the pores in the thermal spray coating and strengthens the coating integrally. Good penetration, sealing properties and sufficient adhesion. Sex is required. That is, if the adhesion between the protective coating and the aluminum alloy sprayed coating, and the sealing property are insufficient, water, chloride, etc., which are components that promote corrosion, sneak up under the protective coating, and undercoat corrosion, Freezing under the coating causes damage and peeling of the coating.

Therefore, as shown in FIG. 1, the protective film 5 on the surface of the heat exchange panel of the open rack type vaporizer according to the present invention is formed of the base material surface 1 of the aluminum alloy material of the heat exchange panel.
, An aluminum alloy such as an Al-Zn alloy is sprayed to form a sprayed coating 2, and then a sealing agent 3 having a low permeability or a colorless and transparent pigment having permeability to the alloy sprayed coating 2 is applied. And then cured to form the sprayed coating 2
A surface layer resin 4 made of an epoxy resin or a urethane resin is applied so as to sufficiently close the pores in the inside, strengthen the coating integrally, and further not to impair the function of the alloy sprayed coating 2 as a sacrificial anode. By curing, it has excellent seawater resistance, cold resistance, and abrasion resistance. In addition,
The laminated coating does not necessarily have to be provided on the entire surface of the heat exchange panel, and at least from the lower side of the heat exchange panel height is 1 /
Providing the desired effect will be achieved by setting it to about 3.

Specifically, the epoxy resin as a penetrating sealing agent is SA Clear manufactured by Shinto Paint Co., Ltd., and the epoxy resin or urethane resin of the surface layer is a metal bond manufactured by General Bond Co. Aluminum or Shinto Paint Co., Ltd. NY Porin K silver and NY Porin K clear are available. The sealing agent is not limited to the above-mentioned epoxy resin, and may be one having excellent penetrability to the aluminum alloy sprayed coating and having a combination compatibility with the epoxy resin or urethane resin of the surface layer. For example, another silicon-based resin, vinyl-based resin, phenol-based resin, urethane-based resin, fluorine-based resin, or other sealing treatment agent can be used.

The above two-layer organic coating film is spray coated,
It is desirable to apply as uniformly as possible by a method such as brush coating. Further, it is important that the cathodic protection function is not impaired even after applying these organic coating films.
Specifically, it is important for the organic coating film on the aluminum alloy sprayed coating to be one that does not interfere with the conduction of anticorrosion current. For that purpose, the coating film thickness is approximately 100 μm.
m or less.

[0014]

According to the present invention, the first organic coating film, that is, a transparent or colorless transparent seal containing a small amount of pigment having permeability is formed on the aluminum alloy sprayed coating on the surface of the heat exchange panel of the open rack type vaporizer. A pore-treating agent is applied to form a base coating film which is excellent in both the adhesion of the thermal spray coating mechanism to the base and the adhesion to the second layer organic coating film, and further seawater resistance, By forming a composite coating with a second organic coating made of epoxy resin or urethane resin, which has excellent cold resistance and abrasion resistance, the durability life of the aluminum alloy sprayed coating against erosion and corrosion is significantly improved. it can.

[0015]

【Example】

Example 1 On the surface of a fin tube constituting a heat exchange panel of an open rack vaporizer, an Al-Zn alloy (A
7072) was formed into a film having a thickness of 200 μm, and then a colorless transparent epoxy resin sealing agent (SA Clear manufactured by Shinto Paint Co., Ltd.) having a permeability was sprayed at a rate of 250 g / m ² to cure the same. In addition, a two-component silver urethane resin enamel paint (Shinto Paint Co., Ltd. NY Porin K Silver)
Was sprayed to form a film having a thickness of about 20 μm, which was applied three times to form a film having a thickness of about 60 μm and cured.

Comparative Example 1 Al-Zn formed on the surface of the fin tube of Example 1
Similarly, only the penetrating epoxy resin sealing agent of Example 1 was applied onto the thermal sprayed alloy-based film.

Comparative Example 2 Al—Zn formed on the surface of the fin tube of Example 1
The polyurethane resin clear paint of Example 1 was similarly applied four times on the system alloy sprayed film to form a film having a thickness of about 60 μm and cured.

Example 2 Al-Zn formed on the surface of the fin tube of Example 1
Similarly, the penetrating epoxy resin sealing treatment agent of Example 1 was applied onto the thermal sprayed alloy-based alloy film, and a two-component colorless transparent urethane resin clear paint (NYPOLIN K manufactured by Shinto Paint Co., Ltd.) was used.
Clear) was sprayed to form a film having a thickness of about 15 μm, which was applied three times to form a film having a thickness of about 45 μm and cured.

Example 3 Al-Zn formed on the surface of the fin tube of Example 1
Similarly, the penetrating epoxy resin sealing agent of Example 1 was applied onto the thermal sprayed alloy coating, and a two-component silver epoxy resin enamel paint (Metal Bond Aluminum manufactured by General Bond Co., Ltd.) was applied by brushing. Then, a film having a thickness of about 100 μm was formed and cured.

Various basic tests using the test heat exchange panel provided with the above-mentioned five types of protective films, and then, as an actual open rack type vaporizer, the surface of the heat exchange panel using seawater mixed with sand and granular shells as a heat medium. Flow down, LNG
Was vaporized over a long period of time, and the state of damage such as cracks and peeling on the coating film after the test was observed and the degree of wear was measured. The measurement results are shown in Table 1, which is shown by the ratio of large and small with reference to Comparative Example 1.

[0021]

[Table 1]

[0022]

Industrial Applicability According to the present invention, an aluminum alloy sprayed coating on the surface of a heat exchange panel of an open rack type vaporizer is coated with a pore-treating agent having a low penetrating pigment or a colorless transparent pore treating agent, An epoxy based coating that seals the thermal spray coating and forms a base coating with excellent adhesion to the base and to the second layer organic coating, as well as seawater resistance, cold resistance and abrasion resistance. By forming a composite coating film having a second organic coating film made of resin or urethane resin, the durability life of the aluminum alloy sprayed coating film against erosion and corrosion can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a vertical cross sectional view showing a laminated state of a protective film layer according to the present invention.

[Explanation of symbols]

 1 Base material surface 2 Alloy sprayed coating 3 Sealing agent 4 Surface layer resin 5 Protective coating

Claims (2)

[Claims] 1. An aluminum alloy sprayed film on a surface of a heat exchange panel made of an aluminum alloy material of an open rack type vaporizer, and a sealing agent which is transparent to the alloy sprayed film and has little pigment or is colorless and transparent. An open rack type vaporizer characterized in that epoxy resin or urethane resin that does not impair the function of the sacrificial anode by the sprayed alloy film is sequentially laminated and cured. 2. An alloy sprayed film, a penetrating sealing agent,
The film thickness of the epoxy resin or urethane resin of the surface layer,
70 to 400 μm, 15 to 30 μm, 45 to 6 respectively
The open rack type vaporizer according to claim 1, wherein the vaporizers are sequentially laminated with a thickness of 0 μm.