JPH0117064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the shape and enameling method of a heat exchanger for a hot water boiler.

[Background of the invention]

Enameling is applied to the water chamber of the heat exchanger to prevent corrosion. There are two methods of enameling. One method involves spraying enamel glaze on each part of the water chamber, firing it, and assembling the parts by welding to form a single heat exchanger. The other method is to first assemble the parts by welding to make a heat exchanger, then inject glaze into the water chamber, rotate and rock the heat exchanger to make it adhere to the water chamber, and drain the remaining glaze. It is then fired.

The shape of a heat exchanger generally consists of a cylindrical inner shell and an outer shell, with the inside of the inner shell serving as a combustion chamber, and the space between the inner shell and the outer shell serving as a water chamber. The connection between the inner shell and the outer shell gradually becomes narrower. For this reason, so-called crevice corrosion occurs in the gaps of this connection, and holes are likely to occur.

[Purpose of the invention]

An object of the present invention is to provide an enameling method that is less likely to cause crevice corrosion.

[Summary of the invention]

In the present invention, after making a heat exchanger, enameling is performed by injecting enamel glaze into the water chamber, and after draining the excess glaze, the gap between the inner and outer shells is fixed downward. , this gap was filled in with extra glaze.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
1 is a cylindrical heat exchanger, and a burner 2 is provided at the bottom of the heat exchanger. The lower part of the cylindrical inner shell 3 serves as a combustion chamber 4, and a combustion chamber 5 is suspended above the combustion chamber 4. The heat exchanger 1 includes an inner shell 3, an outer shell 6, an annular top plate 7 having an upward convex shape, openings 8 for water supply, hot water supply, drainage, etc.
9 and 10, which are assembled by welding. The lower end 3a of the inner shell 3 is diagonally expanded as shown in FIG. 2, and its tip 3b is widened at a small angle for contact with the outer shell 6. Therefore, a gap 11 is created between the two. The discharge port 10 is provided slightly above this gap 11. The lower end corresponds to a bottom plate constituting the lower end of the water chamber. Inner body 3
After the top plate 7 and the top plate 7 are welded together, they are inserted into the outer body 6 and welded together.

Explain the enameling method. After configuring the heat exchanger 1 as described above, glaze is injected into the water chamber 12, and the inside of the water chamber 12 is pressurized with air. Note that each opening 8, 9,
10 is closed. In this state, the lower end side of the heat exchanger 1 is tilted downward at about 45 degrees, and the heat exchanger 1 is rotated at a required rotational speed about the axis of the cylindrical heat exchanger 1. While rotating, the upper end side of the heat exchanger 1 is gradually inclined downward. When the temperature reaches about 45 degrees, gradually return the top end to the upper side. After repeating this for the required number of revolutions, as shown in Figure 3, the
With the opening 10 tilted at about 45 degrees and the opening 10 facing downward, the rotation and tilting movement are stopped, and the opening 10 is opened at the same time. The other openings 8, 9 are closed. Excess glaze remaining without adhering to the surface of the water chamber 12 is forcibly discharged by the air pressure. 13 When the excess glaze shown on the upper surface of the glaze has been discharged, open the openings 8 and 9, stand the heat exchanger 1 vertically with the lower end side facing downward, and blow warm air into the water chamber 12 to dry it. . Next, it is fired in a firing furnace.

The amount (thickness) of the glaze attached to the enamel surface is proportional to the speed at which the glaze moves to the enamel surface. Therefore, the rotational speed and air pressure are determined so as to obtain the required film thickness.

As described above, enameling is performed by injecting an amount of glaze including the surplus into the water chamber, and draining the excess glaze. ing. I try to drain the excess glaze, but it is not completely drained due to the viscosity of the glaze. Therefore, the remaining glaze flows into the gap 11 by standing the heat exchanger 1 upright.
Fill in the relevant section. If fired, it will adhere to the area in this state. Therefore, there are no gaps that would cause crevice corrosion, and crevice corrosion can be prevented. Reference numeral 14 in FIG. 4 shows the enamel that filled the gap 11. Since the heat exchanger 1 is provided with a narrower portion toward the lower side, there is no need to turn the heat exchanger over after firing compared to a case where the portion is provided toward the upper side, making the work easier. It is something that can be done.

Since the top plate 7 is provided in an upwardly convex shape in the upper part of the water chamber 12, no gap is generated.

Note that if corrosion occurs in the gap between the expanded portion 3a and the outer cylinder 6, which gradually narrows, the amount of remaining glaze may be increased to fill the gap. After the glaze is discharged, the amount of glaze that accumulates in the gap 11 can be adjusted by adjusting the height position from the lower end of the discharge port 10 that opens in the outer cylinder 6.

Further, the member constituting the lower part of the water chamber may be a separate member from the inner shell 3. Further, the gap may be located on the inner shell 3 side, or may be located between the inner shell 3 and the outer shell 6.

In addition, if the remaining glaze accumulates in the narrow area at the bottom when the heat exchanger 1 is placed upright even if it is discharged from the upper openings 8 or 9, it may be discharged from the upper openings 8 or 9. good.

In addition, as a method of enameling inside the water chamber 10,
Enameling is done by rotation and pressure, but depending on the glaze selection, enameling can be done simply by pouring and draining.

〔Effect of the invention〕

As described above, according to the present invention, gaps can be filled and crevice corrosion can be prevented.

[Brief explanation of drawings]

The figure shows one embodiment of the present invention.
The figure is a vertical cross-sectional view of the hot water boiler, Figure 2 is an enlarged cross-sectional view of the lower part of the heat exchanger, Figure 3 is a vertical cross-sectional view showing the state in the middle of enameling, and Figure 4 is the lower part of the heat exchanger after enameling. It is an enlarged sectional view. 1... Heat exchanger, 2... Burner, 3... Inner shell,
4...Batsuful, 6...Outer body, 7...Top plate, 8,
9, 10...Opening, 11...Gap, 12...Water chamber.

Claims (1)

[Claims] 1 The upper end side of the water chamber, which is constructed between the inner and outer shells and has an axis in the vertical direction, is an upwardly convex top plate that is welded to the inner and outer shells, and the inner part of the lower end of the water chamber is A connection part between the shell and the outer shell is provided so as to gradually become narrower, the three parts are combined together by welding, and a discharge opening is provided in the outer shell at a position slightly above the lower end of the connection part, and then After injecting more glaze than necessary into the water chamber and enameling, drain the excess glaze, stand the inner and outer shells upright with the connection part facing down, and collect the undischarged glaze in the gap between the connection parts. A method of enameling a heat exchanger, which is characterized in that the above-mentioned gaps are filled with enamel after firing.