JPS60194279A - Water-cooled panel for arc furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a water-cooled panel installed on the wall or lid of a melting furnace, particularly an electric furnace, to reduce wear and tear on refractories, and particularly to reduce spark accidents and heat loss. The present invention relates to a water-cooled panel for arc furnaces that reduces the

In recent years, there has been a remarkable trend towards energy saving and resource saving in conventional arc furnaces for steelmaking, and in particular, the reduction in the unit consumption of refractories for furnace walls and furnace lids has been greatly improved by the application of water-cooled panels.

As for the amount of heat removed from the water-cooled panel, by providing protrusions on the inner surface of the water-cooled panel, slag generated during melting is attached, and the so-called self-coating effect reduces the amount of heat removed, which has been shown to be somewhat effective. was.

However, with recent advances in these technologies, we are now in an era where further power savings and cost minimization are sought after, and the reduction of heat loss by cooling water from water-cooled panels, which was not a problem at the conventional level, has come into focus.

In the conventional method, it is expected that the inner surface of the water-cooled panel will be coated with slag, but if too much slag is deposited, it will fall off at a certain point, and at that time, the surface of the water-cooled panel will be exposed to the arc from the electrode, causing rapid removal. There are practical difficulties such as generation of heat, and it has not always been satisfactory in terms of energy conservation.

On the other hand, as in Utility Model Application No. 49-118635 shown in FIG.
In addition to b), a method of casting a cooling water pipe (c) inside the furnace was also devised, but the cast brick part was worn out quickly and the long-term effect could not be expected. Due to the structure in which bricks are cast, bricks cannot be attached to the entire surface of the water-cooled panel and can only be applied partially, so the effect of reducing heat loss cannot be expected to be large.Although it is a temporary improvement, it is not enough. The effect of reducing the amount of heat removed could not be achieved.

OBJECTS OF THE INVENTION In view of these current circumstances, the present invention provides a substantially effective water-cooled panel for arc furnaces that has a long service life, prevents spark accidents, and reduces the amount of heat removed.

Structure of the Invention In a high-power arc furnace, especially in a high-power arc furnace, the heat load on the furnace wall near the electrodes, the so-called hot spot, is extremely high.Therefore, the brick furnace wall is subject to significant wear and tear. Moreover, even when using water-cooled panels, the amount of heat removed would be excessive, and there was currently no rational countermeasure.

The present invention attempts to eliminate this drawback by applying ceramics with extremely high heat resistance to the hot spot portion. However, the disadvantages of ceramics are that they are susceptible to shock and break easily, and large plates are difficult and expensive to manufacture.Furthermore, the amount of thermal expansion increases in proportion to the size. It also had the disadvantage that it was difficult to absorb thermal expansion.

This method focuses on the fact that these drawbacks of ceramics can be solved by distributing a large number of small ceramic pieces (any shape with the longest dimension of 400m+m or less, preferably 300m+m or less) in the form of tiles. By rationally applying it to a water-cooled panel, it provides a structure that is compatible with the furnace wall and furnace lid of an arc furnace.

Figure 2.3.4 shows an embodiment of the structure of the present invention,
A water cooling jacket 2 is installed inside the body shell 1 of the arc furnace, and a water cooling jacket 2' is installed on the furnace lid. A water supply pipe 3.3' is provided on the outside of the furnace of the water cooling jacket 2.2'. Cooling water flows through the water cooling jacket from the water supply pipe 3.3', and a drain pipe 4 is provided at a separate location. .4' It is designed to be discharged outside the furnace.

Now, focusing on the water-cooled panel on the furnace wall, a small ceramic piece 6 is provided on the surface 5a of the furnace inner shell 5 of the water cooling jacket 2, and in this embodiment, the furnace inner shell 5 has a diameter of 105 mm (A). Stud pins 7 attached by welding are provided at intervals of . The stud pin 7 can be made of metal or non-metal such as ceramics or brick. If it is made of metal, it may be attached by threaded joints in addition to welding, or if it is non-metallic, it may be attached by threaded joints. The ceramic piece 6 has an opening 8 for passing the stud pin 7, while the stud pin 7 has a screw 7.
A is provided, and a mounting nut 9 that engages with it is mounted. Like the stand pin 7, this mounting nut 9 is also made of metal or non-metal such as ceramics or brick. After installing the small ceramic piece 6 by passing the stud pin 7 through the opening 8 so as to make contact with the furnace inner shell 5, the ceramic piece 6 is tightened and fixed by screwing the nut 9 onto the stud pin 7. It is composed of

FIG. 3 is a view taken along arrow A-A in FIG.
It has a rectangular shape of 0.0l1c), with a gap of about 0.2 to 10mm) between the adjacent ceramic pieces 6.
On the other hand, it is constructed so that thermal expansion can escape. Although the ceramic is square in this embodiment, it is not limited to this and may have any shape. Furthermore, when the water cooling jacket is used for a long period of time, it may be slightly deformed due to heat, but since the ceramic pieces 6 are small and have a tile-like structure, the ceramic pieces 6 do not crack and the water cooling jacket deforms. We are now able to respond immediately.

In addition, ceramics inherently maintain a high degree of chemical uniformity, mechanical properties, and physical properties in small pieces of about 400mm x 400+++s, and are cheaper in terms of price as they can be manufactured using a small firing section. By making it into small pieces, it is possible to have many advantages.

Furthermore, even if some of the large number of small pieces fall off due to cracks, most of them do not fall off all at once, as in the case of conventional slag, but the process progresses gradually. The effect is that it will not suddenly become unusable, and it can be expected to have a long lifespan until most of it falls off.

The thickness is 5 mm or more and 100 mm or less. 5■
In the following cases, the ceramic pieces become weak as an individual and are likely to break.Also, it may be possible to apply a ceramic coating by spraying, but this is extremely brittle and impractical. Therefore, the thickness is preferably 5 mm or more.

If it exceeds 10100 f11, it will be expensive and the difference in thermal expansion within the material will also increase, so a thickness of 100 mm or less is actually a reasonable thickness. Regarding the quality of the ceramic, the material should have an apparent porosity of 20% or less, and the material should be basic or neutral, and acidic materials should not be used because they will be eroded by slag.

In addition, regarding the heat removal effect, considering the case where the maximum heat load is applied at the hot spot area, as shown in Table 1,
In the conventional method (Fig. 8), even when slag adhesion is resistant (Fig. 9), it is 130 x 104 kcal/m'
h, while the amount of heat removed in one embodiment of the present invention (first
In Figure 0), the thermal conductivity of ceramics is 2.3 k.
cal/mh"o, 35X104kcal/m
The amount of heat removed by the conventional method can be reduced to approximately 58%.

The same thing can be said about the furnace wall or furnace lid other than the hot spot, and in this case, ceramics with even lower heat resistance can be selected, making it possible to apply a variety of materials and providing high compatibility. .

Also, one of the major effects of covering the inner surface with ceramics is that ceramics have a high electrical resistance, so it has the effect of preventing short circuits of current from the electrodes. In the conventional method, the surface of the water cooling jacket was exposed to the electrode, so the current from the electrode could sometimes be short-circuited to the water cooling jacket.
The water cooling panel was partially melted due to the excessive current.
Water leakage and damage often occurred. In the structure of the present invention, since the water cooling jacket surface is covered with ceramics, it is possible to prevent this accidental short circuit phenomenon from occurring, and stable operation of the water cooling panel is enabled.

In the structure shown in FIG. 5, the ceramics are fixed using a heat-resistant adhesive IO without using a threaded joint. The adhesive performance of the adhesive is greatly influenced by the difference in thermal expansion between the ceramic and the water cooling jacket during heating, and if the difference in thermal expansion is large, the adhesive will be sheared and the ceramic will fall off. However, in the present invention, since the ceramic is composed of small pieces with a side of at most 400 mm, the difference in thermal expansion is small.
It can be installed without falling off.

In particular, with recent remarkable progress in heat-resistant adhesives, it is easy to obtain adhesives that are sufficiently heat-resistant for the boundary temperature (T2) of 220° C. in the examples shown in Table 1.

FIG. 6 shows another embodiment in which ceramics are attached using a threaded joint and an adhesive.

Although FIG. 7 shows an example in which the hook-shaped stopper 11 is welded to the furnace inner shell 5 and the ceramic 6 is attached, it may also be attached using a screw joint. In addition to metal, this stopper can also be made of ceramics, bricks, etc., and in this case, it can be fixed using a method such as a screw joint.

Note that the protrusions for attaching slugs provided on conventional water-cooled panels can also be provided on the panel of the present invention, for example, as shown in FIG. ), or by attaching the protrusion 12 by welding or the like, or by attaching it alone on the furnace inner surface 5a of the water cooling jacket 5 (not shown).
.

Effects of the Invention As described above in detail, the present invention significantly saves energy and resources in an arc furnace.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional water-cooled panel, FIG. 2 is a sectional view of a water-cooled panel of the present invention, and FIG. 3 is a view taken along the line A-A in FIG.
Figure 4 is a view from the B-B arrow in Figure 3, and is an explanatory diagram of ceramics attached with stud pins, Figure 5 is an explanatory diagram of ceramics attached with heat-resistant adhesive, and Figure 6 is an explanatory diagram of ceramics attached with stud pins. Figure 7 is an explanatory diagram of the ceramics attached using adhesive, Figure 7 is an explanatory diagram of the ceramics attached with a hook type fastener, Figures 8 to 10 are explanatory diagrams of the heat removal effect, and Figure 8 is an illustration of the ceramics without slag adhesion resistance. The conventional method, FIG. 9 shows the conventional method when slag is attached, and FIG. 1θ shows an example of the present invention. ae...water cooling panel, b...brick, C...cooling water pipe, l...fist arc furnace body shell, 2.2' battle...
Water cooling jacket, 3.3' Φ... Water supply pipe, 4.4'
... Drain pipe, 5.5' ... Hearth inner shell, 5a.
・Surface of the inner shell of the water cooling jacket, 6.6'
... Ceramic small piece 7.7' ... Stud pin, 7a... Knuckle screw, 8... Hole for passing the φ stud pin, 9... Mounting nut, 10... Φ heat-resistant adhesive,
11... Φ hook type stopper, 12-... protrusion. Patent Applicant Nippon Steel Corporation Agent Patent Attorney Masaru Inoue Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6F! ! J Figure 7 5a Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] A water cooling panel for an arc furnace, which is installed on the furnace wall and lid of an arc furnace and configured to be able to supply and drain cooling water, characterized in that a small piece of ceramic is attached to the inside surface of the water cooling panel. panel.