JPS58221342A - Heat exchanger for bath boiler - Google Patents

Abstract

PURPOSE:To prevent the adhesion of impurities, increase anti-corrosion properties from the inner and outer surfaces and improve the durability of the bath boiler by a method wherein a film consisting of an inorganic polymer is formed on the outer surface while another film prominent in the non-adhesive properties thereof is formed on the inorganic polymer film to apply double coating to the inner surface of the heat exchanger for the bath boiler made of the base material of aluminum series. CONSTITUTION:The double coating consisting of the inorganic polymer film 9 and the non-adhesive film 10 is applied to the inner surface of the heat exchanger 1 made of the base material 8 of aluminum while the inorganic polyme film 9 is formed on the outer surface of the heat exchanger. The film 9 is an inorganic coating having the binder of the silicate of alkaline metal and the resistances to heat and corrosion are prominent. The non-adhesive film 10 is made of fluorine plastics or the like and prominent in the non-adhesive properties. The whole of the inner and outer surfaces, which are holding clean surfaces, are processed by the inorganic polymer film, therefore, the outer surface increases the anti-corrosion properties and the durabilities, the inner surface is kept in a clean surface at all times, troubles due to the adhesion of scale or the like may be eliminated, while the life as the bath boiler may be elongated remakably and the deterioration of a heat efficiency may also be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger for a bathtub using aluminum or aluminum casting as a base material, and aims to improve its corrosion resistance and durability.

Conventionally, boehmite and alumite treatment have been most commonly used for heat exchangers for bathtubs using aluminum-based materials as a base material.

However, in the case of bath kettles, the bathtub is often left filled with water, and the environment in which it is used is harsh.
There is a problem that it lacks corrosion resistance.

In particular, there are many cases in which corrosion progresses through pinholes existing in the treated film, and scale and the like adhere to the treated film, which acts as a nucleus and causes pitting corrosion.

In addition, the outer surface (combustion side) is attacked by acid and heat due to the effects of exhaust gas and condensation, and the inner and outer surfaces are exposed to a corrosive environment.

Aluminum has good thermal conductivity and is lightweight. Furthermore, although it has excellent workability and is suitable as a substrate material U for heat exchangers, it has problems in terms of corrosion resistance and durability as mentioned above, and there is a strong demand for improvement from the market. was.

The present invention has been devised and improved in view of such problems and eliminates the conventional drawbacks. After forming the first coating layer made of an inorganic polymer, a second layer of non-adhesive film is formed on the first layer film made of the inorganic polymer to coat the inner surface. It is double coated. The outer surface (combustion side) improves heat resistance, combustion gas resistance, dew condensation resistance, etc., and the inner surface (water side) improves the adhesion of scale, various secretions mixed in hot water in the bathtub, and various impurities. This prevents corrosion and further improves the adhesion with aluminum, increasing corrosion resistance on both the inside and outside, and improving the durability of the bathtub.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of the bathtub and the bathtub, and FIG. 2 is a schematic enlarged view of the inside and outside of the heat exchanger.

In FIG. 1, reference numeral 1 denotes a heat exchanger for a bathtub made of A4 material, which is connected to a bathtub 7 through an inlet pipe 3 and an outlet pipe 4. The tapping pipe 4 has fins 2 with a constant pitch.
is provided. The heat exchanger 1 is housed in a can body 6 together with a burner 6 located below the heat exchanger 1 to constitute a bathtub.

Furthermore, as shown in Fig. 2, the heat exchanger 1 has a first tube on the inner surface (water side).
A double coating of a coating 9 on a base material 8 made of an inorganic polymer and a second coating 1o having non-adhesive properties is made as a layer,
An inorganic polymer film 9 is formed on the outer surface (combustion side). As an example of surface treatment, the film 9 on the base material 8 made of an inorganic polymer includes a coating film of an inorganic paint containing an alkali metal silicate as a binder.

Water-based coatings have good heat resistance, acid resistance, combustion gas resistance, and corrosion resistance. Excellent for
It also has various characteristics such as hardness and density as a coating film, and is suitable as a material for treating the entire inner and outer surfaces of a heat exchanger. Next, the second non-adhesive film to be formed on the inner surface may be made of fluororesin, or a blend type or copolymer type with fluororesin.

These coatings have good physical properties such as hot water resistance, boiling water resistance, and steam resistance, as well as water scale resistance.

It has excellent non-stick properties against scale components such as hot water scale, various secretions from the body, oils and fats, etc., and is not only corrosion resistant, but also maintains a clean surface and is extremely good in terms of thermal efficiency. It is.

As mentioned above, heat exchangers for bathtubs based on aluminum or aluminum or cast iron can be used under extremely harsh conditions.
used in the environment. The outer surface is naturally heated with a gas burner, so it absorbs heat, combustion exhaust gas, water vapor,
Furthermore, the inner surface is exposed to acids (HNO3, etc.) generated by the mixing of NOx contained in exhaust gas into the dew condensation water, and the inner surface becomes
Attacks from both the inside and outside, such as the effects of salt dissolved in the hot water, oil and fat secretions, bath salts, etc., scale adhesion in the water and hot water, and the risk of pitting corrosion caused by this scale adhesion. However, by treating the entire inner and outer surfaces of the heat exchanger with a film made of inorganic polymer, the corrosion resistance and durability of the outer surface in the above environment can be dramatically improved. On the inner surface, this first layer film treatment plays a role as a pretreatment when treating the second layer, and also contributes to improving adhesion. Since it is the same inorganic material as , it is thought that it promotes scale adhesion due to its affinity with scale, but since a non-adhesive film is formed as a second layer treatment to create a double coating. Such concerns are completely eliminated, the inner surface is always kept clean, a decrease in thermal efficiency due to scale adhesion and abnormal overheating are prevented, and corrosion resistance and durability are significantly improved.

As described above, according to the heat exchanger for bathtubs of the present invention, the outer surface is coated with a film made of an inorganic polymer, and the inner surface is double-coated with a film that has excellent non-stick properties. This eliminates problems caused by corrosion and adhesion of scale in a relatively short period of time as in the past, significantly extending the lifespan of the bathtub, and preventing a decrease in thermal efficiency, among other benefits. .

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the state of a bathtub over bathtub, and FIG. 2 is an enlarged sectional view showing a treated wall surface of a heat exchanger for a bathtub made of aluminum or aluminum casting as a base material. 1...Heat exchanger, 2...Fin, 3.
...Water inlet pipe, 4...Hot water outlet pipe, 7...
...Bathtub, 8.Mark/base material, 9.River...Inorganic polymer film, 10..Non-adhesive film.

Claims (1)

[Claims] Heat exchanger for bathtubs using A4 or A4 casting as the base material.
(2) A coating layer made of an inorganic polymer is formed on the entire outer surface, and a non-adhesive film is formed on the inner surface to form a double coating. Heat exchanger for bathtubs.